Interactions between Equibron G and Verapamil
1 drug interaction and 44 additional warnings found for the following 2 drugs:
- Equibron G (guaifenesin/theophylline)
- verapamil
Drug interactions
Moderate drug interactions
Moderate:
verapamil theophylline
Applies to: verapamil and Equibron G (guaifenesin / theophylline)
Monitor
Verapamil may increase theophylline serum levels, theophylline effect, and risk of toxicity. The mechanism is inhibition of CYP450 hepatic metabolism by verapamil. Other hepatically metabolized methylxanthines may also be affected. Cigarette smokers appear to have a greater risk of developing theophylline toxicity from this combination.
Management
Clinical monitoring of patient response and tolerance and serum theophylline levels is recommended. Patients should be advised to report any signs of theophylline toxicity including nausea, vomiting, diarrhea, headache, restlessness, insomnia, or irregular heartbeat to their physicians. Theophylline dosage should be reduced as appropriate. Isradipine and nifedipine appear to have minimal effects on theophylline pharmacokinetics.
References (8)
- Abernethy DR, Egan JM, Dickinson TH, Carrum G (1988) "Substrate-selective inhibition by verapamil and diltiazem: differential disposition of antipyrine and theophylline in humans." J Pharmacol Exp Ther, 244, p. 994-9
- McTavish D, Sorkin EM (1989) "Verapamil: an updated review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in hypertension." Drugs, 38, p. 19-76
- Fuhr U, Woodcock BG, Siewart M (1992) "Verapamil and drug metabolism by the cytochrome p450 isoform CYP1A2." Eur J Clin Pharmacol, 42, p. 463-4
- Stringer KA, Mallet J, Clarke M, Lindenfield JA (1992) "The effect of three different oral doses of verapamil on the disposition of theophylline." Eur J Clin Pharmacol, 43, p. 35-8
- Gin AS, Stringer KA, Welage LS, et al. (1989) "The efect of verapamil on the pharmacokinetic disposition of theophylline in cigarette smokers." J Clin Pharmacol, 29, p. 728-32
- Nielsen-Kudsk JE, Buhl JS, Johannessen AC (1990) "Verapamil-induced inhibition of theophylline elimination in healthy humans." Pharmacol Toxicol, 66, p. 101-3
- Upton RA (1991) "Pharmacokinetic interactions between theophylline and other medication (Part II)." Clin Pharmacokinet, 20, p. 135-50
- Taniguchi A, Ohe T, Shimorura K (1989) "Theophylline-induced ventricular tachycardia in a patient with chronic lung disease: sensitivity to verapamil." Chest, 96, p. 958-9
Food/lifestyle interactions
Moderate food/lifestyle interactions
Moderate:
verapamil Food/Lifestyle
Applies to: verapamil
Generally avoid
Consumption of large quantities of grapefruit juice may be associated with significantly increased plasma concentrations of oral verapamil. The mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. One study reported no significant effect of a single administration of grapefruit juice on the pharmacokinetics of verapamil in ten hypertensive patients receiving chronic therapy. In another study conducted in nine healthy male volunteers, administration of 120 mg oral verapamil twice daily for 3 days following pretreatment with 200 mL grapefruit juice twice daily for 5 days resulted in a 57% increase in S-verapamil peak plasma concentration (Cmax), a 36% increase in S-verapamil systemic exposure (AUC), a 40% increase in R-verapamil Cmax, and a 28% increase in R-verapamil AUC compared to administration following orange juice. Elimination half-life and renal clearance of both S- and R-verapamil were not affected by grapefruit juice, and there were no significant effects on blood pressure, heart rate, or PR interval. A third study reported a 1.63-fold increase in Cmax and a 1.45-fold increase in AUC of (R,S)-verapamil in 24 young, healthy volunteers given verapamil sustained-release 120 mg twice daily for 7 days with 250 mL grapefruit juice four times daily on days 5 through 7. Two subjects developed PR interval prolongation of more than 350 ms during grapefruit juice coadministration. A high degree of interindividual variability has been observed in these studies. The interaction was also suspected in a case report of a 42-year-old woman who developed complete heart block, hypotension, hypoxic respiratory failure, severe anion gap metabolic acidosis, and hyperglycemia following accidental ingestion of three verapamil sustained-release 120 mg tablets over a span of six hours. The patient's past medical history was remarkable only for migraine headaches, for which she was receiving several medications including verapamil. Prior to admission, the patient had a 2-week history of poorly controlled migraine, and the six hours preceding hospitalization she suffered from worsening headache and palpitations progressing to altered sensorium. An extensive workup revealed elevated verapamil and norverapamil levels more than 4.5 times above the upper therapeutic limits. These levels also far exceeded those reported in the medical literature for patients taking verapamil 120 mg every 6 hours, or 480 mg in a 24-hour period. The patient recovered after receiving ventilator and vasopressor support. Upon questioning, it was discovered that the patient had been drinking large amounts of grapefruit juice (3 to 4 liters total) the week preceding her admission due to nausea. No other sources or contributing factors could be found for the verapamil toxicity.
Management
Patients treated with oral verapamil should avoid the consumption of large amounts of grapefruit or grapefruit juice to prevent any undue fluctuations in serum drug levels. Patients should be advised to seek medical attention if they experience edema or swelling of the lower extremities; sudden, unexplained weight gain; difficulty breathing; chest pain or tightness; or hypotension as indicated by dizziness, fainting, or orthostasis.
References (9)
- McAllister RG, Jr (1982) "Clinical pharmacology of slow channel blocking agents." Prog Cardiovasc Dis, 25, p. 83-102
- (2001) "Product Information. Covera-HS (verapamil)." Searle
- Zaidenstein R, Dishi V, Gips M, Soback S, Cohen N, Weissgarten J, Blatt A, Golik A (1998) "The effect of grapefruit juice on the pharmacokinetics of orally administered verapamil." Eur J Clin Pharmacol, 54, p. 337-40
- Ho PC, Ghose K, Saville D, Wanwimolruk S (2000) "Effect of grapefruit juice on pharmacokinetics and pharmacodynamics of verapamil enantiomers in healthy volunteers." Eur J Clin Pharmacol, 56, p. 693-8
- Fuhr U, Muller-Peltzer H, Kern R, et al. (2002) "Effects of grapefruit juice and smoking on verapamil concentrations in steady state." Eur J Clin Pharmacol, 58, p. 45-53
- Bailey DG, Dresser GK (2004) "Natural products and adverse drug interactions." Can Med Assoc J, 170, p. 1531-2
- Bailey DG, Malcolm J, Arnold O, Spence JD (2004) "Grapefruit juice-drug interactions. 1998." Br J Clin Pharmacol, 58, S831-40; discussion S841-3
- Arayne MS, Sultana N, Bibi Z (2005) "Review: grape fruit juice - drug interactions." Pak J Pharm Sci, 18, p. 45-57
- Pillai U, Muzaffar J, Sandeep S, Yancey A (2009) "Grapefruit juice and verapamil: a toxic cocktail." South Med J, 102, p. 308-9
Moderate:
theophylline Food/Lifestyle
Applies to: Equibron G (guaifenesin / theophylline)
Generally avoid
Coadministration with caffeine may increase the serum concentrations of theophylline. The proposed mechanism involves competitive inhibition of theophylline metabolism via CYP450 1A2, as well as metabolic conversion of caffeine to theophylline in vivo and saturation of theophylline metabolism at higher serum concentrations. In six healthy male volunteers (all smokers), serum concentrations of theophylline (administered as aminophylline 400 mg single oral dose) were significantly higher following consumption of caffeine (2 to 7 cups of instant coffee over 24 hours, equivalent to approximately 120 to 630 mg of caffeine) than after caffeine deprivation for 48 hours. Caffeine consumption also increased the apparent elimination half-life of theophylline by an average of 32% and reduced its total body clearance by 23%. In another study, steady-state concentration and area under the concentration-time curve of theophylline (1200 mg intravenously over 24 hours) increased by 23% and 40%, respectively, in eight healthy volunteers following administration of caffeine (300 mg orally three times a day).
Management
Given the narrow therapeutic index of theophylline, patients should limit or avoid significant fluctuations in their intake of pharmacologic as well as dietary caffeine.
Adjust dosing interval
Administration of theophylline with continuous enteral nutrition may reduce the serum levels or the rate of absorption of theophylline. The mechanism has not been reported. In one case, theophylline levels decreased by 53% in a patient receiving continuous nasogastric tube feedings and occurred with both theophylline tablet and liquid formulations, but not with intravenous aminophylline.
Management
When administered to patients receiving continuous enteral nutrition , some experts recommend that the tube feeding should be interrupted for at least 1 hour before and 1 hour after the dose of theophylline is given; rapid-release formulations are preferable, and theophylline levels should be monitored.
References (3)
- Jonkman JH, Sollie FA, Sauter R, Steinijans VW (1991) "The influence of caffeine on the steady-state pharmacokinetics of theophylline." Clin Pharmacol Ther, 49, p. 248-55
- Sato J, Nakata H, Owada E, Kikuta T, Umetsu M, Ito K (1993) "Influence of usual intake of dietary caffeine on single-dose kinetics of theophylline in healthy human subjects." Eur J Clin Pharmacol, 44, p. 295-8
- Wohlt PD, Zheng L, Gunderson S, Balzar SA, Johnson BD, Fish JT (2009) "Recommendations for the use of medications with continuous enteral nutrition." Am J Health Syst Pharm, 66, p. 1438-67
Moderate:
verapamil Alcohol (Ethanol)
Applies to: verapamil
Generally avoid
Verapamil may increase the blood concentrations and intoxicating effects of ethanol. The exact mechanism of interaction is unknown but may involve verapamil inhibition of ethanol metabolism. In 10 healthy, young volunteers, verapamil (80 mg orally every 8 hours for 6 days) increased the mean peak blood concentration (Cmax) and the 12-hour area under the concentration-time curve (AUC) of ethanol (0.8 g/kg single oral dose) by 17% and 30%, respectively, compared to placebo. Verapamil AUCs were positively correlated to increased ethanol blood AUC values. Subjectively (i.e. each subject's perception of intoxication as measured on a visual analog scale), verapamil also significantly increased the area under the ethanol effect versus time curve but did not change the peak effect or time to peak effect.
Management
Patients treated with verapamil should be counseled to avoid alcohol consumption.
References (2)
- Bauer LA, Schumock G, Horn J, Opheim K (1992) "Verapamil inhibits ethanol elimination and prolongs the perception of intoxication." Clin Pharmacol Ther, 52, p. 6-10
- (2001) "Product Information. Isoptin (verapamil)." Knoll Pharmaceutical Company
Moderate:
verapamil multivitamins with minerals
Applies to: verapamil
Monitor
Calcium-containing products may decrease the effectiveness of calcium channel blockers by saturating calcium channels with calcium. Calcium chloride has been used to manage acute severe verapamil toxicity.
Management
Management consists of monitoring the effectiveness of calcium channel blocker therapy during coadministration with calcium products.
References (14)
- Henry M, Kay MM, Viccellio P (1985) "Cardiogenic shock associated with calcium-channel and beta blockers: reversal with intravenous calcium chloride." Am J Emerg Med, 3, p. 334-6
- Moller IW (1987) "Cardiac arrest following intravenous verapamil combined with halothane anaesthesia." Br J Anaesth, 59, p. 522-6
- Oszko MA, Klutman NE (1987) "Use of calcium salts during cardiopulmonary resuscitation for reversing verapamil-associated hypotension." Clin Pharm, 6, p. 448-9
- Schoen MD, Parker RB, Hoon TJ, et al. (1991) "Evaluation of the pharmacokinetics and electrocardiographic effects of intravenous verapamil with intravenous calcium chloride pretreatment in normal subjects." Am J Cardiol, 67, p. 300-4
- O'Quinn SV, Wohns DH, Clarke S, Koch G, Patterson JH, Adams KF (1990) "Influence of calcium on the hemodynamic and anti-ischemic effects of nifedipine observed during treadmill exercise testing." Pharmacotherapy, 10, p. 247
- Woie L, Storstein L (1981) "Successful treatment of suicidal verapamil poisoning with calcium gluconate." Eur Heart J, 2, p. 239-42
- Morris DL, Goldschlager N (1983) "Calcium infusion for reversal of adverse effects of intravenous verapamil." JAMA, 249, p. 3212-3
- Guadagnino V, Greengart A, Hollander G, Solar M, Shani J, Lichstein E (1987) "Treatment of severe left ventricular dysfunction with calcium chloride in patients receiving verapamil." J Clin Pharmacol, 27, p. 407-9
- Luscher TF, Noll G, Sturmer T, Huser B, Wenk M (1994) "Calcium gluconate in severe verapamil intoxication." N Engl J Med, 330, p. 718-20
- Bar-Or D, Gasiel Y (1981) "Calcium and calciferol antagonise effect of verapamil in atrial fibrillation." Br Med J (Clin Res Ed), 282, p. 1585-6
- Lipman J, Jardine I, Roos C, Dreosti L (1982) "Intravenous calcium chloride as an antidote to verapamil-induced hypotension." Intensive Care Med, 8, p. 55-7
- McMillan R (1988) "Management of acute severe verapamil intoxication." J Emerg Med, 6, p. 193-6
- Perkins CM (1978) "Serious verapamil poisoning: treatment with intravenous calcium gluconate." Br Med J, 2, p. 1127
- Moroni F, Mannaioni PF, Dolara A, Ciaccheri M (1980) "Calcium gluconate and hypertonic sodium chloride in a case of massive verapamil poisoning." Clin Toxicol, 17, p. 395-400
Moderate:
theophylline Caffeine
Applies to: Equibron G (guaifenesin / theophylline)
Generally avoid
Coadministration with caffeine may increase the serum concentrations of theophylline. The proposed mechanism involves competitive inhibition of theophylline metabolism via CYP450 1A2, as well as metabolic conversion of caffeine to theophylline in vivo and saturation of theophylline metabolism at higher serum concentrations. In six healthy male volunteers (all smokers), serum concentrations of theophylline (administered as aminophylline 400 mg single oral dose) were significantly higher following consumption of caffeine (2 to 7 cups of instant coffee over 24 hours, equivalent to approximately 120 to 630 mg of caffeine) than after caffeine deprivation for 48 hours. Caffeine consumption also increased the apparent elimination half-life of theophylline by an average of 32% and reduced its total body clearance by 23%. In another study, steady-state concentration and area under the concentration-time curve of theophylline (1200 mg intravenously over 24 hours) increased by 23% and 40%, respectively, in eight healthy volunteers following administration of caffeine (300 mg orally three times a day).
Management
Given the narrow therapeutic index of theophylline, patients should limit or avoid significant fluctuations in their intake of pharmacologic as well as dietary caffeine.
References (2)
- Jonkman JH, Sollie FA, Sauter R, Steinijans VW (1991) "The influence of caffeine on the steady-state pharmacokinetics of theophylline." Clin Pharmacol Ther, 49, p. 248-55
- Sato J, Nakata H, Owada E, Kikuta T, Umetsu M, Ito K (1993) "Influence of usual intake of dietary caffeine on single-dose kinetics of theophylline in healthy human subjects." Eur J Clin Pharmacol, 44, p. 295-8
Moderate:
theophylline Nicotine
Applies to: Equibron G (guaifenesin / theophylline)
Monitor
Smoking cessation may lead to elevated plasma concentrations and enhanced pharmacologic effects of drugs that are substrates of CYP450 1A2 (and possibly CYP450 1A1) and/or certain drugs with a narrow therapeutic index (e.g., flecainide, pentazocine). One proposed mechanism is related to the loss of CYP450 1A2 and 1A1 induction by polycyclic aromatic hydrocarbons in tobacco smoke; when smoking cessation agents are initiated and smoking stops, the metabolism of certain drugs may decrease leading to increased plasma concentrations. The mechanism by which smoking cessation affects narrow therapeutic index drugs that are not known substrates of CYP450 1A2 or 1A1 is unknown. The clinical significance of this interaction is unknown as clinical data are lacking.
Management
Until more information is available, caution is advisable if smoking cessation agents are used concomitantly with drugs that are substrates of CYP450 1A2 or 1A1 and/or those with a narrow therapeutic range. Patients receiving smoking cessation agents may require periodic dose adjustments and closer clinical and laboratory monitoring of medications that are substrates of CYP450 1A2 or 1A1.
References (4)
- (2024) "Product Information. Cytisine (cytisinicline)." Consilient Health Ltd
- jeong sh, Newcombe D, sheridan j, Tingle M (2015) "Pharmacokinetics of cytisine, an a4 b2 nicotinic receptor partial agonist, in healthy smokers following a single dose." Drug Test Anal, 7, p. 475-82
- Vaughan DP, Beckett AH, Robbie DS (1976) "The influence of smoking on the intersubject variation in pentazocine elimination." Br J Clin Pharmacol, 3, p. 279-83
- Zevin S, Benowitz NL (1999) "Drug interactions with tobacco smoking: an update" Clin Pharmacokinet, 36, p. 425-38
Disease interactions
38 potential interactions Applies to: 34 conditions, including High Blood Pressure, GERD, Underactive Thyroid, Heart Failure, and Heart Attack.
Angina
Moderate:
Equibron G
The theophylline in Equibron G has a moderate potential interaction with Angina.
The use of theophyllines is associated with an increase in heart rate which may progress to supraventricular tachycardia or ventricular arrhythmia at high serum drug concentrations. Appearance of cardiac adverse effects is generally an indication of theophylline toxicity, although patients with a history of tachyarrhythmias may be more susceptible to the chronotropic effect of these drugs. Therapy with theophyllines should be administered cautiously in such patients. Caution is also advised in patients with hypertension, hyperthyroidism, angina pectoris, or recent myocardial infarction, since high dosages of the drugs are associated with positive inotropic as well as chronotropic effects. Clinical monitoring of serum drug concentrations is recommended to prevent toxicity.
Aortic Stenosis
Major:
verapamil
Verapamil has a major potential interaction with Aortic Stenosis.
The use of some calcium channel blockers (CCBs) is contraindicated in patients with advanced aortic stenosis. CCBs whose pharmacologic effect is partially dependent on their ability to reduce afterload (e.g., diltiazem, nicardipine, nifedipine, verapamil) may be of less benefit in these patients due to a fixed impedance to flow across the aortic valve and may, in fact, worsen rather than improve myocardial oxygen balance. Rarely, heart failure has developed following the initiation of these CCBs, particularly in patients receiving concomitant beta-blocker therapy.
Cardiogenic Shock
Major:
verapamil
Verapamil has a major potential interaction with Cardiogenic Shock.
In general, calcium channel blockers (CCBs) should not be used in patients with hypotension (systolic pressure < 90 mm Hg) or cardiogenic shock. Due to potential negative inotropic and peripheral vasodilating effects, the use of CCBs may further depress cardiac output and blood pressure, which can be detrimental in these patients. The use of verapamil and diltiazem is specifically contraindicated under these circumstances.
Cerebral Vascular Disorder
Major:
Equibron G
The theophylline in Equibron G has a major potential interaction with Cerebral Vascular Disorder.
The use of theophyllines is considered by some manufacturers to be contraindicated in patients with underlying seizure disorders unless they are receiving adequate anticonvulsant therapy. Theophyllines may cause seizures, which have generally been associated with toxic drug levels but have also been reported at therapeutic concentrations in patients with head trauma or cerebral infarct. If theophylline therapy is administered in patients with these or other risk factors for seizures, serum drug levels should be monitored closely and maintained in the low therapeutic range. Intractable seizures and death have been reported during acute theophylline toxicity.
Cor Pulmonale
Moderate:
Equibron G
The theophylline in Equibron G has a moderate potential interaction with Cor Pulmonale.
Certain conditions have been identified as causes of reduced theophylline clearance. They include age (neonates and infants < 1 year as well as elderly patients > 60 years) and the following concurrent diseases: acute pulmonary edema; decompensated heart failure; cor pulmonale; fever (>= 102 degrees for 24 hours or more, or lesser temperature elevations for longer periods); influenza; untreated or uncontrolled hypothyroidism; liver disease, cirrhosis or acute hepatitis; reduced renal function in infants < 3 months of age; sepsis with multi-organ failure; and shock. Therapy with theophyllines should be administered cautiously in patients presenting with one or more of these risk factors, and the dosage should be appropriately reduced to prevent toxicity. More intensive monitoring of serum theophylline concentrations may be required. Toxicity is most likely to occur when levels exceed 20 mcg/mL. Severe cases, sometimes without previous warning, have led to cardiac arrhythmias, intractable seizures, and death.
Fever
Moderate:
Equibron G
The theophylline in Equibron G has a moderate potential interaction with Fever.
Certain conditions have been identified as causes of reduced theophylline clearance. They include age (neonates and infants < 1 year as well as elderly patients > 60 years) and the following concurrent diseases: acute pulmonary edema; decompensated heart failure; cor pulmonale; fever (>= 102 degrees for 24 hours or more, or lesser temperature elevations for longer periods); influenza; untreated or uncontrolled hypothyroidism; liver disease, cirrhosis or acute hepatitis; reduced renal function in infants < 3 months of age; sepsis with multi-organ failure; and shock. Therapy with theophyllines should be administered cautiously in patients presenting with one or more of these risk factors, and the dosage should be appropriately reduced to prevent toxicity. More intensive monitoring of serum theophylline concentrations may be required. Toxicity is most likely to occur when levels exceed 20 mcg/mL. Severe cases, sometimes without previous warning, have led to cardiac arrhythmias, intractable seizures, and death.
Gastrointestinal Obstruction
Moderate:
verapamil
Verapamil has a moderate potential interaction with Gastrointestinal Obstruction.
The controlled-onset, extended-release formulation of verapamil (Covera-HS) contains a non-deformable material. There have been rare reports of obstructive symptoms in patients with known strictures following the ingestion of similar sustained-release products. Therapy with the controlled-onset, extended-release formulation of verapamil should be administered cautiously in patients with preexisting severe gastrointestinal narrowing or obstruction, whether pathologic or iatrogenic.
GERD
Moderate:
Equibron G
The theophylline in Equibron G has a moderate potential interaction with GERD.
Methylxanthines increase gastric acidity and may also relax lower esophageal sphincter, which can lead to gastric reflux into the esophagus. Therapy with products containing methylxanthines should be administered cautiously in patients with significant gastroesophageal reflux.
Head Injury
Major:
Equibron G
The theophylline in Equibron G has a major potential interaction with Head Injury.
The use of theophyllines is considered by some manufacturers to be contraindicated in patients with underlying seizure disorders unless they are receiving adequate anticonvulsant therapy. Theophyllines may cause seizures, which have generally been associated with toxic drug levels but have also been reported at therapeutic concentrations in patients with head trauma or cerebral infarct. If theophylline therapy is administered in patients with these or other risk factors for seizures, serum drug levels should be monitored closely and maintained in the low therapeutic range. Intractable seizures and death have been reported during acute theophylline toxicity.
Heart Attack
Major:
verapamil
Verapamil has a major potential interaction with Heart Attack.
The use of verapamil is contraindicated in patients with severe left ventricular dysfunction (e.g., ejection fraction < 30%) or moderate to severe symptoms of cardiac failure and in patients with any degree of ventricular dysfunction if they are receiving a beta-adrenergic blocker. Likewise, verapamil should not be given to patients with acute myocardial infarction and pulmonary congestion documented by X-ray on admission, since associated heart failure may be acutely worsened. Verapamil has a negative inotropic effect, which in most patients is compensated by a simultaneous reduction in afterload (i.e. decreased systemic vascular resistance) without a net impairment of ventricular performance. However, congestive heart failure or pulmonary edema have developed in approximately 2% of patients treated with verapamil. Mild symptoms of cardiac failure should be under control, if possible, prior to initiating verapamil therapy.
Moderate:
Equibron G
The theophylline in Equibron G has a moderate potential interaction with Heart Attack.
The use of theophyllines is associated with an increase in heart rate which may progress to supraventricular tachycardia or ventricular arrhythmia at high serum drug concentrations. Appearance of cardiac adverse effects is generally an indication of theophylline toxicity, although patients with a history of tachyarrhythmias may be more susceptible to the chronotropic effect of these drugs. Therapy with theophyllines should be administered cautiously in such patients. Caution is also advised in patients with hypertension, hyperthyroidism, angina pectoris, or recent myocardial infarction, since high dosages of the drugs are associated with positive inotropic as well as chronotropic effects. Clinical monitoring of serum drug concentrations is recommended to prevent toxicity.
Heart Block
Major:
verapamil
Verapamil has a major potential interaction with Heart Block.
The use of some calcium channel blockers (CCBs) is contraindicated in patients with severe bradyarrhythmia, sick sinus syndrome (unless a functioning pacemaker is present), or heart block greater than the first degree (unless a functioning pacemaker is present). CCBs like bepridil, diltiazem and verapamil have a negative effect on AV conduction and the SA node and may exacerbate these conditions.
Heart Failure
Major:
verapamil
Verapamil has a major potential interaction with Heart Failure.
The use of verapamil is contraindicated in patients with severe left ventricular dysfunction (e.g., ejection fraction < 30%) or moderate to severe symptoms of cardiac failure and in patients with any degree of ventricular dysfunction if they are receiving a beta-adrenergic blocker. Likewise, verapamil should not be given to patients with acute myocardial infarction and pulmonary congestion documented by X-ray on admission, since associated heart failure may be acutely worsened. Verapamil has a negative inotropic effect, which in most patients is compensated by a simultaneous reduction in afterload (i.e. decreased systemic vascular resistance) without a net impairment of ventricular performance. However, congestive heart failure or pulmonary edema have developed in approximately 2% of patients treated with verapamil. Mild symptoms of cardiac failure should be under control, if possible, prior to initiating verapamil therapy.
Moderate:
Equibron G
The theophylline in Equibron G has a moderate potential interaction with Heart Failure.
Certain conditions have been identified as causes of reduced theophylline clearance. They include age (neonates and infants < 1 year as well as elderly patients > 60 years) and the following concurrent diseases: acute pulmonary edema; decompensated heart failure; cor pulmonale; fever (>= 102 degrees for 24 hours or more, or lesser temperature elevations for longer periods); influenza; untreated or uncontrolled hypothyroidism; liver disease, cirrhosis or acute hepatitis; reduced renal function in infants < 3 months of age; sepsis with multi-organ failure; and shock. Therapy with theophyllines should be administered cautiously in patients presenting with one or more of these risk factors, and the dosage should be appropriately reduced to prevent toxicity. More intensive monitoring of serum theophylline concentrations may be required. Toxicity is most likely to occur when levels exceed 20 mcg/mL. Severe cases, sometimes without previous warning, have led to cardiac arrhythmias, intractable seizures, and death.
Hemodialysis
Moderate:
Equibron G
The theophylline in Equibron G has a moderate potential interaction with Hemodialysis.
Theophylline is removed by hemodialysis. Doses should either be scheduled for administration after dialysis or supplemental doses be given after dialysis.
High Blood Pressure
Moderate:
Equibron G
The theophylline in Equibron G has a moderate potential interaction with High Blood Pressure.
The use of theophyllines is associated with an increase in heart rate which may progress to supraventricular tachycardia or ventricular arrhythmia at high serum drug concentrations. Appearance of cardiac adverse effects is generally an indication of theophylline toxicity, although patients with a history of tachyarrhythmias may be more susceptible to the chronotropic effect of these drugs. Therapy with theophyllines should be administered cautiously in such patients. Caution is also advised in patients with hypertension, hyperthyroidism, angina pectoris, or recent myocardial infarction, since high dosages of the drugs are associated with positive inotropic as well as chronotropic effects. Clinical monitoring of serum drug concentrations is recommended to prevent toxicity.
Hyperthyroidism
Moderate:
Equibron G
The theophylline in Equibron G has a moderate potential interaction with Hyperthyroidism.
The use of theophyllines is associated with an increase in heart rate which may progress to supraventricular tachycardia or ventricular arrhythmia at high serum drug concentrations. Appearance of cardiac adverse effects is generally an indication of theophylline toxicity, although patients with a history of tachyarrhythmias may be more susceptible to the chronotropic effect of these drugs. Therapy with theophyllines should be administered cautiously in such patients. Caution is also advised in patients with hypertension, hyperthyroidism, angina pectoris, or recent myocardial infarction, since high dosages of the drugs are associated with positive inotropic as well as chronotropic effects. Clinical monitoring of serum drug concentrations is recommended to prevent toxicity.
Hypertrophic Cardiomyopathy
Major:
verapamil
Verapamil has a major potential interaction with Hypertrophic Cardiomyopathy.
The use of verapamil in patients with hypertrophic cardiomyopathy, or idiopathic hypertrophic subaortic stenosis, has been associated with serious side effects such as pulmonary edema, severe hypotension, sinus bradycardia, AV block, sinus arrest, and death. However, a causal relationship has not been established. Therapy with verapamil should be administered cautiously in patients with hypertrophic cardiomyopathy. Dosage reduction or drug discontinuation may be required if severe adverse effects occur.
Hypotension
Major:
verapamil
Verapamil has a major potential interaction with Hypotension.
In general, calcium channel blockers (CCBs) should not be used in patients with hypotension (systolic pressure < 90 mm Hg) or cardiogenic shock. Due to potential negative inotropic and peripheral vasodilating effects, the use of CCBs may further depress cardiac output and blood pressure, which can be detrimental in these patients. The use of verapamil and diltiazem is specifically contraindicated under these circumstances.
Influenza
Moderate:
Equibron G
The theophylline in Equibron G has a moderate potential interaction with Influenza.
Certain conditions have been identified as causes of reduced theophylline clearance. They include age (neonates and infants < 1 year as well as elderly patients > 60 years) and the following concurrent diseases: acute pulmonary edema; decompensated heart failure; cor pulmonale; fever (>= 102 degrees for 24 hours or more, or lesser temperature elevations for longer periods); influenza; untreated or uncontrolled hypothyroidism; liver disease, cirrhosis or acute hepatitis; reduced renal function in infants < 3 months of age; sepsis with multi-organ failure; and shock. Therapy with theophyllines should be administered cautiously in patients presenting with one or more of these risk factors, and the dosage should be appropriately reduced to prevent toxicity. More intensive monitoring of serum theophylline concentrations may be required. Toxicity is most likely to occur when levels exceed 20 mcg/mL. Severe cases, sometimes without previous warning, have led to cardiac arrhythmias, intractable seizures, and death.
Ischemic Heart Disease
Major:
verapamil
Verapamil has a major potential interaction with Ischemic Heart Disease.
Increased frequency, duration, and/or severity of angina, as well as acute myocardial infarction, have rarely developed during initiation or dosage increase of calcium channel blockers (CCBs), particularly in patients with severe obstructive coronary artery disease and those treated with immediate-release formulations. The mechanism of this effect is not established. Therapy with CCBs should be administered cautiously in patients with significant coronary artery disease.
Liver Disease
Major:
verapamil
Verapamil has a major potential interaction with Liver Disease.
Calcium channel blockers (CCBs) are extensively metabolized by the liver. The half-lives of CCBs may be prolonged substantially in patients with severe hepatic impairment, with the potential for significant drug accumulation. In addition, the use of some CCBs has been associated with elevations in serum transaminases, both with and without concomitant elevations in alkaline phosphatase and bilirubin. While these effects may be transient and reversible, some patients have developed cholestasis or hepatocellular injury. Therapy with CCBs should be administered cautiously and often at reduced dosages in patients with significantly impaired hepatic function. Periodic monitoring of liver function is advised.
Moderate:
Equibron G
The theophylline in Equibron G has a moderate potential interaction with Liver Disease.
Certain conditions have been identified as causes of reduced theophylline clearance. They include age (neonates and infants < 1 year as well as elderly patients > 60 years) and the following concurrent diseases: acute pulmonary edema; decompensated heart failure; cor pulmonale; fever (>= 102 degrees for 24 hours or more, or lesser temperature elevations for longer periods); influenza; untreated or uncontrolled hypothyroidism; liver disease, cirrhosis or acute hepatitis; reduced renal function in infants < 3 months of age; sepsis with multi-organ failure; and shock. Therapy with theophyllines should be administered cautiously in patients presenting with one or more of these risk factors, and the dosage should be appropriately reduced to prevent toxicity. More intensive monitoring of serum theophylline concentrations may be required. Toxicity is most likely to occur when levels exceed 20 mcg/mL. Severe cases, sometimes without previous warning, have led to cardiac arrhythmias, intractable seizures, and death.
Myoneural Disorder
Moderate:
verapamil
Verapamil has a moderate potential interaction with Myoneural Disorder.
Verapamil has been reported to decrease neuromuscular transmission in patients with Duchenne's muscular dystrophy and to prolong recovery from the neuromuscular blocking agent, vecuronium. Therapy with verapamil should be administered cautiously in patients with attenuated neuromuscular transmission or myopathy, since these conditions may be exacerbated. A reduced dosage may be appropriate.
Myopathy
Moderate:
verapamil
Verapamil has a moderate potential interaction with Myopathy.
Verapamil has been reported to decrease neuromuscular transmission in patients with Duchenne's muscular dystrophy and to prolong recovery from the neuromuscular blocking agent, vecuronium. Therapy with verapamil should be administered cautiously in patients with attenuated neuromuscular transmission or myopathy, since these conditions may be exacerbated. A reduced dosage may be appropriate.
Panhypopituitarism
Moderate:
Equibron G
The theophylline in Equibron G has a moderate potential interaction with Panhypopituitarism.
Certain conditions have been identified as causes of reduced theophylline clearance. They include age (neonates and infants < 1 year as well as elderly patients > 60 years) and the following concurrent diseases: acute pulmonary edema; decompensated heart failure; cor pulmonale; fever (>= 102 degrees for 24 hours or more, or lesser temperature elevations for longer periods); influenza; untreated or uncontrolled hypothyroidism; liver disease, cirrhosis or acute hepatitis; reduced renal function in infants < 3 months of age; sepsis with multi-organ failure; and shock. Therapy with theophyllines should be administered cautiously in patients presenting with one or more of these risk factors, and the dosage should be appropriately reduced to prevent toxicity. More intensive monitoring of serum theophylline concentrations may be required. Toxicity is most likely to occur when levels exceed 20 mcg/mL. Severe cases, sometimes without previous warning, have led to cardiac arrhythmias, intractable seizures, and death.
Peptic Ulcer
Major:
Equibron G
The theophylline in Equibron G has a major potential interaction with Peptic Ulcer.
Methylxanthines are known to stimulate peptic acid secretion. Therapy with products containing methylxanthines should be administered with extreme caution in patients with active peptic ulcer disease. Some manufacturers consider their use to be contraindicated under such circumstance.
Post MI Syndrome
Moderate:
Equibron G
The theophylline in Equibron G has a moderate potential interaction with Post MI Syndrome.
The use of theophyllines is associated with an increase in heart rate which may progress to supraventricular tachycardia or ventricular arrhythmia at high serum drug concentrations. Appearance of cardiac adverse effects is generally an indication of theophylline toxicity, although patients with a history of tachyarrhythmias may be more susceptible to the chronotropic effect of these drugs. Therapy with theophyllines should be administered cautiously in such patients. Caution is also advised in patients with hypertension, hyperthyroidism, angina pectoris, or recent myocardial infarction, since high dosages of the drugs are associated with positive inotropic as well as chronotropic effects. Clinical monitoring of serum drug concentrations is recommended to prevent toxicity.
Preexcitation Syndrome
Major:
verapamil
Verapamil has a major potential interaction with Preexcitation Syndrome.
The use of verapamil is contraindicated for the management of atrial flutter or fibrillation in patients with an accessory AV tract (e.g., those with Wolff-Parkinson-White or Lown-Ganong-Levine syndrome). Intravenous verapamil has been reported to cause ventricular fibrillation and cardiac arrest in such patients, the mechanism of which is related to the drug's ability to shorten the refractory period and accelerate antegrade conduction within the accessory pathway. Although these events have not been associated with chronic use of oral verapamil, a similar risk may exist.
Pulmonary Edema
Moderate:
Equibron G
The theophylline in Equibron G has a moderate potential interaction with Pulmonary Edema.
Certain conditions have been identified as causes of reduced theophylline clearance. They include age (neonates and infants < 1 year as well as elderly patients > 60 years) and the following concurrent diseases: acute pulmonary edema; decompensated heart failure; cor pulmonale; fever (>= 102 degrees for 24 hours or more, or lesser temperature elevations for longer periods); influenza; untreated or uncontrolled hypothyroidism; liver disease, cirrhosis or acute hepatitis; reduced renal function in infants < 3 months of age; sepsis with multi-organ failure; and shock. Therapy with theophyllines should be administered cautiously in patients presenting with one or more of these risk factors, and the dosage should be appropriately reduced to prevent toxicity. More intensive monitoring of serum theophylline concentrations may be required. Toxicity is most likely to occur when levels exceed 20 mcg/mL. Severe cases, sometimes without previous warning, have led to cardiac arrhythmias, intractable seizures, and death.
Renal Dysfunction
Major:
Equibron G
The theophylline in Equibron G has a major potential interaction with Renal Dysfunction.
The metabolites of theophylline, which are generally undetectable in patients with normal renal function, may accumulate in patients with renal impairment and contribute to the toxicity of theophylline. In addition, the plasma protein binding of theophylline may be significantly decreased in renal impairment, resulting in elevated free drug concentrations and further increasing the risk of toxicity. Therapy with theophyllines should be administered cautiously in patients with impaired renal function. Dosage adjustments and more intensive monitoring of serum theophylline concentrations may be required.
Moderate:
verapamil
Verapamil has a moderate potential interaction with Renal Dysfunction.
Approximately 70% of an administered dose of verapamil is excreted as metabolites in the urine. The primary metabolite, norverapamil, has about 20% the cardiovascular activity and can reach steady-state plasma concentrations approaching those of the parent drug. Patients with impaired renal function may be at greater risk for adverse effects due to drug and metabolite accumulation. Therapy with verapamil should be administered cautiously in such patients, with appropriate monitoring for excessive pharmacologic effects (e.g., abnormal prolongation of PR interval) and the dosage adjusted accordingly as necessary.
Seizures
Major:
Equibron G
The theophylline in Equibron G has a major potential interaction with Seizures.
The use of theophyllines is considered by some manufacturers to be contraindicated in patients with underlying seizure disorders unless they are receiving adequate anticonvulsant therapy. Theophyllines may cause seizures, which have generally been associated with toxic drug levels but have also been reported at therapeutic concentrations in patients with head trauma or cerebral infarct. If theophylline therapy is administered in patients with these or other risk factors for seizures, serum drug levels should be monitored closely and maintained in the low therapeutic range. Intractable seizures and death have been reported during acute theophylline toxicity.
Shock
Moderate:
Equibron G
The theophylline in Equibron G has a moderate potential interaction with Shock.
Certain conditions have been identified as causes of reduced theophylline clearance. They include age (neonates and infants < 1 year as well as elderly patients > 60 years) and the following concurrent diseases: acute pulmonary edema; decompensated heart failure; cor pulmonale; fever (>= 102 degrees for 24 hours or more, or lesser temperature elevations for longer periods); influenza; untreated or uncontrolled hypothyroidism; liver disease, cirrhosis or acute hepatitis; reduced renal function in infants < 3 months of age; sepsis with multi-organ failure; and shock. Therapy with theophyllines should be administered cautiously in patients presenting with one or more of these risk factors, and the dosage should be appropriately reduced to prevent toxicity. More intensive monitoring of serum theophylline concentrations may be required. Toxicity is most likely to occur when levels exceed 20 mcg/mL. Severe cases, sometimes without previous warning, have led to cardiac arrhythmias, intractable seizures, and death.
Sinus Node Dysfunction
Major:
verapamil
Verapamil has a major potential interaction with Sinus Node Dysfunction.
The use of some calcium channel blockers (CCBs) is contraindicated in patients with severe bradyarrhythmia, sick sinus syndrome (unless a functioning pacemaker is present), or heart block greater than the first degree (unless a functioning pacemaker is present). CCBs like bepridil, diltiazem and verapamil have a negative effect on AV conduction and the SA node and may exacerbate these conditions.
Tachyarrhythmia
Moderate:
Equibron G
The theophylline in Equibron G has a moderate potential interaction with Tachyarrhythmia.
The use of theophyllines is associated with an increase in heart rate which may progress to supraventricular tachycardia or ventricular arrhythmia at high serum drug concentrations. Appearance of cardiac adverse effects is generally an indication of theophylline toxicity, although patients with a history of tachyarrhythmias may be more susceptible to the chronotropic effect of these drugs. Therapy with theophyllines should be administered cautiously in such patients. Caution is also advised in patients with hypertension, hyperthyroidism, angina pectoris, or recent myocardial infarction, since high dosages of the drugs are associated with positive inotropic as well as chronotropic effects. Clinical monitoring of serum drug concentrations is recommended to prevent toxicity.
Underactive Thyroid
Moderate:
Equibron G
The theophylline in Equibron G has a moderate potential interaction with Underactive Thyroid.
Certain conditions have been identified as causes of reduced theophylline clearance. They include age (neonates and infants < 1 year as well as elderly patients > 60 years) and the following concurrent diseases: acute pulmonary edema; decompensated heart failure; cor pulmonale; fever (>= 102 degrees for 24 hours or more, or lesser temperature elevations for longer periods); influenza; untreated or uncontrolled hypothyroidism; liver disease, cirrhosis or acute hepatitis; reduced renal function in infants < 3 months of age; sepsis with multi-organ failure; and shock. Therapy with theophyllines should be administered cautiously in patients presenting with one or more of these risk factors, and the dosage should be appropriately reduced to prevent toxicity. More intensive monitoring of serum theophylline concentrations may be required. Toxicity is most likely to occur when levels exceed 20 mcg/mL. Severe cases, sometimes without previous warning, have led to cardiac arrhythmias, intractable seizures, and death.
Ventricular Arrhythmia
Major:
verapamil
Verapamil has a major potential interaction with Ventricular Arrhythmia.
The use of intravenous diltiazem or verapamil is contraindicated in patients with ventricular tachycardia. IV administration of a calcium channel blocker can precipitate cardiac arrest in such patients. Marked hemodynamic deterioration and ventricular fibrillation have occurred in patients with wide-complex ventricular tachycardia (QRS >= 0.12 seconds) treated with IV verapamil.
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Equibron G
A total of 335 drugs are known to interact with Equibron G.
- Equibron g is in the drug class antiasthmatic combinations.
- Equibron g is used to treat the following conditions:
verapamil
A total of 719 drugs are known to interact with verapamil.
- Verapamil is in the following drug classes: calcium channel blockers, group IV antiarrhythmics.
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Verapamil is used to treat the following conditions:
- Angina
- Arrhythmia
- Atrial Tachycardia (off-label)
- Bipolar Disorder (off-label)
- Cluster Headaches (off-label)
- Headache
- High Blood Pressure
- Idiopathic Hypertrophic Subaortic Stenosis (off-label)
- Migraine
- Migraine Prevention (off-label)
- Nocturnal Leg Cramps (off-label)
- Supraventricular Tachycardia (off-label)
Drug Interaction Classification
| Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit. | |
| Moderately clinically significant. Usually avoid combinations; use it only under special circumstances. | |
| Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan. | |
| No interaction information available. |
Further information
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