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Drug Interactions between amlodipine / perindopril and ephedrine / phenobarbital / potassium iodide / theophylline

This report displays the potential drug interactions for the following 2 drugs:

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Major

PHENobarbital amLODIPine

Applies to: ephedrine / phenobarbital / potassium iodide / theophylline and amlodipine / perindopril

GENERALLY AVOID: Potent inducers of CYP450 3A4 may significantly decrease the plasma concentrations of calcium channel blockers, the majority of which are primarily metabolized by the isoenzyme. Undetectable plasma levels have been reported for some calcium blockers when given orally.

MANAGEMENT: Concomitant use of calcium channel blockers with potent CYP450 3A4 inducers should generally be avoided. If coadministration is necessary, pharmacologic response should be monitored more closely following the initiation or discontinuation of the CYP450 3A4 inducer, and the CCB dosage adjusted accordingly.

References

  1. Tada Y, Tsuda Y, Otsuka T, et al. "Case report: nifedipine-rifampicin interaction attenuates the effect on blood pressure in a patient with essential hypertension." Am J Med Sci 303 (1992): 25-7
  2. "Product Information. Mycobutin (rifabutin)." Pharmacia and Upjohn PROD (2001):
  3. "Product Information. Rifadin (rifampin)." Hoechst Marion Roussel PROD (2001):

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Major

potassium iodide perindopril

Applies to: ephedrine / phenobarbital / potassium iodide / theophylline and amlodipine / perindopril

MONITOR CLOSELY: Concomitant use of angiotensin converting enzyme (ACE) inhibitors and potassium salts may increase the risk of hyperkalemia. Inhibition of ACE results in decreased aldosterone secretion, which in turn causes potassium retention. In one report, a significant increase in serum potassium level (3.88 +/- 0.41 to 4.84 +/- 0.45 mEq/L) was observed within one or two days following the addition of captopril in five patients who were treated with regimens that included potassium supplements or potassium-sparing diuretics. Three patients had laboratory-diagnosed hyperkalemia, including one patient receiving potassium supplementation who had a 66% increase in serum potassium. Levels remained elevated until potassium supplementation or captopril therapy was reduced or discontinued. In a postmarketing survey of patients who were prescribed enalapril in England between April and December 1985, researchers identified ten cases where enalapril appeared to have contributed to a deterioration in renal function and subsequent death. All ten patients had hyperkalemia, and seven were also receiving moderate to high dosages of potassium-sparing diuretics and/or potassium supplements. Hyperkalemia was felt to be the immediate cause of death in two of them. Risk factors for developing severe or life-threatening hyperkalemia may include renal impairment, diabetes, old age, severe or worsening heart failure, dehydration, and concomitant use of other agents that block the renin-angiotensin-aldosterone system or otherwise increase serum potassium levels.

MANAGEMENT: Caution is advised if ACE inhibitors must be used concurrently with potassium salts, particularly in patients with renal impairment, diabetes, old age, severe or worsening heart failure, dehydration, or concomitant therapy with other agents that increase serum potassium such as nonsteroidal anti-inflammatory drugs, beta-blockers, cyclosporine, heparin, tacrolimus, trimethoprim, and licorice. The combination should generally be avoided in these patients unless absolutely necessary and the benefits outweigh the potential risks. Serum potassium and renal function should be checked prior to initiating therapy and regularly thereafter. Patients should be given counseling on the appropriate levels of potassium and fluid intake, and advised to seek medical attention if they experience signs and symptoms of hyperkalemia such as nausea, vomiting, weakness, listlessness, tingling of the extremities, paralysis, confusion, weak pulse, and a slow or irregular heartbeat.

References

  1. Speirs CJ, Dollery CT, Inman WH, et al. "Postmarketing surveillance of enalapril II: investigation of the potential role of enalapril in deaths with renal failure." Br Med J 297 (1988): 830-2
  2. Packer M, Lee WH "Provocation of hyper- and hypokalemic sudden death during treatment with and withdrawal of converting-enzyme inhibition in severe chronic congestive heart failure." Am J Cardiol 57 (1986): 347-8
  3. Burnakis TG, Mioduch HJ "Combined therapy with captopril and potassium supplementation: a potential for hyperkalemia." Arch Intern Med 144 (1984): 2371-2
  4. Warren SE, O'Connor DT "Hyperkalemia resulting from captopril administration." JAMA 244 (1980): 2551-2
  5. Chan TY, Critchley JA "Life-threatening hyperkalaemia in an elderly patient receiving captopril, furosemide (frusemide) and potassium supplements." Drug Saf 7 (1992): 159-61
  6. Walmsley RN, White GH, Cain M, McCarthy PJ, Booth J "Hyperkalemia in the elderly." Clin Chem 30 (1984): 1409-12
  7. Stoltz ML, Andrews CE Jr "Severe hyperkalemia during very-low-calorie diets and angiotensin converting enzyme use ." JAMA 264 (1990): 2737-8
  8. Ponce SP, Jennings AE, Madias NE, Harrington JT "Drug-induced hyperkalemia." Medicine (Baltimore) 64 (1985): 357-70
  9. Lawson DH, O'Connor PC, Jick H "Drug attributed alterations in potassium handling in congestive cardiac failure." Eur J Clin Pharmacol 23 (1982): 21-5
  10. Lawson DH "Adverse reactions to potassium chloride." Q J Med 43 (1974): 433-40
  11. "Product Information. K-Dur (potassium chloride)." Schering Corporation PROD (2001):
  12. Good CB, McDermott L "Diet and serum potassium in patients on ACE inhibitors." JAMA 274 (1995): 538
  13. Graves JW "Hyperkalemia due to a potassium-based water softener." N Engl J Med 339 (1998): 1790-1
  14. Obialo CI, Ofili EO, Mirza T "Hyperkalemia in congestive heart failure patients aged 63 to 85 years with subclinical renal disease." Am J Cardiol 90 (2002): 663-5
  15. Atlas SA, Case DB, Sealey JE, Laragh JH, McKinstry DN "Interruption of the renin-angiotensin system in hypertensive patients by captopril induces sustained reduction in aldosterone secretion, potassium retention and natriuresis." Hypertension 1 (1979): 279-80
  16. Schuna AA, Schmidt GR, Pitterle ME "Serum potassium concentrations after initiation of captopril therapy." Clin Pharm 5 (1986): 920-3
  17. Jarman PR, Mather HM "Diabetes may be independent risk factor for hyperkalaemia." BMJ 327 (2003): 812
  18. Ray K, Dorman S, Watson R "Severe hyperkalaemia due to the concomitant use of salt substitutes and ACE inhibitors in hypertension: a potentially life threatening interaction." J Hum Hypertens 13 (1999): 717-20
  19. Reardon LC, Macpherson DS "Hyperkalemia in outpatients using angiotensin-converting enzyme inhibitors. How much should we worry?" Arch Intern Med 158 (1998): 26-32
  20. Perazella MA "Drug-induced hyperkalemia: old culprits and new offenders." Am J Med 109 (2000): 307-14
  21. Jarman PR, Kehely AM, Mather HM "Hyperkalaemia in diabetes: prevalence and associations." Postgrad Med J 71 (1995): 551-2
  22. Perazella MA, Mahnensmith RL "Hyperkalemia in the elderly: drugs exacerbate impaired potassium homeostasis." J Gen Intern Med 12 (1997): 646-56
  23. Schoolwerth AC, Sica DA, Ballermann BJ, Wilcox CS, Council on the Kidney in Cardiovascular Disease and the Council for High Blood Pressure Research of the American Heart Association "Renal considerations in angiotensin converting enzyme inhibitor therapy: a statement for healthcare professionals from the Council on the Kidney in Cardiovascular Disease and the Council for High Blood Pressure Research of the American Heart Association." Circulation 104 (2001): 1985-91
  24. Large DM, Carr PH, Laing I, Davies M "Hyperkalaemia in diabetes mellitus--potential hazards of coexisting hyporeninaemic hypoaldosteronism." Postgrad Med J 60 (1984): 370-3
View all 24 references

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Moderate

theophylline PHENobarbital

Applies to: ephedrine / phenobarbital / potassium iodide / theophylline and ephedrine / phenobarbital / potassium iodide / theophylline

MONITOR: Barbiturates may decrease serum levels and therapeutic effects of the methylxanthines. The mechanism is barbiturate induction of CYP450 3A4 and 1A2 hepatic metabolism of methylxanthines.

MANAGEMENT: Close observation for clinical and laboratory evidence of decreased methylxanthine effect is indicated if these drugs must be used together. Patients should be advised to notify their physician if they experience a worsening of their respiratory symptoms.

References

  1. Upton RA "Pharmacokinetic interactions between theophylline and other medication (Part I)." Clin Pharmacokinet 20 (1991): 66-80
  2. Bukowskyj M, Nakatsu K, Munt PW "Theophylline reassessed." Ann Intern Med 101 (1984): 63-73
  3. Landay RA, Gonzalez MA, Taylor JC "Effect of phenobarbital on theophylline disposition." J Allergy Clin Immunol 62 (1978): 27-9
  4. Dahlqvist R, Steiner E, Koike Y, von Bahr C, Lind M, Billing B "Induction of theophylline metabolism by pentobarbital." Ther Drug Monit 11 (1989): 408-10
View all 4 references

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Moderate

PHENobarbital perindopril

Applies to: ephedrine / phenobarbital / potassium iodide / theophylline and amlodipine / perindopril

MONITOR: Many psychotherapeutic and CNS-active agents (e.g., anxiolytics, sedatives, hypnotics, antidepressants, antipsychotics, opioids, alcohol, muscle relaxants) exhibit hypotensive effects, especially during initiation of therapy and dose escalation. Coadministration with antihypertensives and other hypotensive agents, in particular vasodilators and alpha-blockers, may result in additive effects on blood pressure and orthostasis.

MANAGEMENT: Caution and close monitoring for development of hypotension is advised during coadministration of these agents. Some authorities recommend avoiding alcohol in patients receiving vasodilating antihypertensive drugs. Patients should be advised to avoid rising abruptly from a sitting or recumbent position and to notify their physician if they experience dizziness, lightheadedness, syncope, orthostasis, or tachycardia.

References

  1. Sternbach H "Fluoxetine-associated potentiation of calcium-channel blockers." J Clin Psychopharmacol 11 (1991): 390-1
  2. Shook TL, Kirshenbaum JM, Hundley RF, Shorey JM, Lamas GA "Ethanol intoxication complicating intravenous nitroglycerin therapy." Ann Intern Med 101 (1984): 498-9
  3. Feder R "Bradycardia and syncope induced by fluoxetine." J Clin Psychiatry 52 (1991): 139
  4. Ellison JM, Milofsky JE, Ely E "Fluoxetine-induced bradycardia and syncope in two patients." J Clin Psychiatry 51 (1990): 385-6
  5. Rodriguez de la Torre B, Dreher J, Malevany I, et al. "Serum levels and cardiovascular effects of tricyclic antidepressants and selective serotonin reuptake inhibitors in depressed patients." Ther Drug Monit 23 (2001): 435-40
  6. Cerner Multum, Inc. "Australian Product Information." O 0
  7. Pacher P, Kecskemeti V "Cardiovascular side effects of new antidepressants and antipsychotics: new drugs, old concerns?" Curr Pharm Des 10 (2004): 2463-75
  8. Andrews C, Pinner G "Postural hypotension induced by paroxetine." BMJ 316 (1998): 595
View all 8 references

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Minor

theophylline ePHEDrine

Applies to: ephedrine / phenobarbital / potassium iodide / theophylline and ephedrine / phenobarbital / potassium iodide / theophylline

Ephedrine-methylxanthine combinations are used for the treatment of asthma but the efficacy of the combination has been questioned. This combination may lead to increased xanthine side effects. The mechanism is unknown, but may be related to synergistic pharmacologic effects. Patients using this combination should be closely monitored for side effects such as nausea, vomiting, tachycardia, nervousness, or insomnia. If side effects are noted, the dosage of the xanthine may need to be decreased.

References

  1. Weinberger M, Bronsky E, Bensch GW, Bock GN, Yecies JJ "Interaction of ephedrine and theophylline." Clin Pharmacol Ther 17 (1975): 585-92
  2. Sims JA, doPico GA, Reed CE "Bronchodilating effect of oral theophylline-ephedrine combination." J Allergy Clin Immunol 62 (1978): 15-21
  3. Tinkelman DG, Avner SE "Ephedrine therapy in asthmatic children. Clinical tolerance and absence of side effects." JAMA 237 (1977): 553-7
  4. Weinberger MM, Brousky EA "Evaluation of oral bronchodilator therapy in asthmatic children: bronchodilators in asthmatic children." J Pediatr 84 (1974): 421-7
  5. Badiei B, Faciane J, Sly M "Effect of throphylline, ephedrine and theri combination upon exercise-induced airway obstruction." Ann Allergy 35 (1975): 32-6
View all 5 references

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Minor

amLODIPine perindopril

Applies to: amlodipine / perindopril and amlodipine / perindopril

Calcium channel blockers and angiotensin converting enzyme (ACE) inhibitors may have additive hypotensive effects. While these drugs are often safely used together, careful monitoring of the systemic blood pressure is recommended during coadministration, especially during the first one to three weeks of therapy.

References

  1. Kaplan NM "Amlodipine in the treatment of hypertension." Postgrad Med J 67 Suppl 5 (1991): s15-9
  2. DeQuattro V "Comparison of benazepril and other antihypertensive agents alone and in combination with the diuretic hydrochlorothiazide." Clin Cardiol 14 (1991): iv28-32;
  3. Sun JX, Cipriano A, Chan K, John VA "Pharmacokinetic interaction study between benazepril and amlodipine in healthy subjects." Eur J Clin Pharmacol 47 (1994): 285-9
  4. Di Somma S, et al. "Antihypertensive effects of verapamil, captopril and their combination at rest and during dynamic exercise." Arzneimittelforschung 42 (1992): 103
View all 4 references

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Drug and food interactions

Major

PHENobarbital food

Applies to: ephedrine / phenobarbital / potassium iodide / theophylline

GENERALLY AVOID: Concurrent acute use of barbiturates and ethanol may result in additive CNS effects, including impaired coordination, sedation, and death. Tolerance of these agents may occur with chronic use. The mechanism is related to inhibition of microsomal enzymes acutely and induction of hepatic microsomal enzymes chronically.

MANAGEMENT: The combination of ethanol and barbiturates should be avoided.

References

  1. Gupta RC, Kofoed J "Toxological statistics for barbiturates, other sedatives, and tranquilizers in Ontario: a 10-year survey." Can Med Assoc J 94 (1966): 863-5
  2. Misra PS, Lefevre A, Ishii H, Rubin E, Lieber CS "Increase of ethanol, meprobamate and pentobarbital metabolism after chronic ethanol administration in man and in rats." Am J Med 51 (1971): 346-51
  3. Saario I, Linnoila M "Effect of subacute treatment with hypnotics, alone or in combination with alcohol, on psychomotor skills related to driving." Acta Pharmacol Toxicol (Copenh) 38 (1976): 382-92
  4. Stead AH, Moffat AC "Quantification of the interaction between barbiturates and alcohol and interpretation of fatal blood concentrations." Hum Toxicol 2 (1983): 5-14
  5. Seixas FA "Drug/alcohol interactions: avert potential dangers." Geriatrics 34 (1979): 89-102
View all 5 references

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Moderate

theophylline food

Applies to: ephedrine / phenobarbital / potassium iodide / 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

  1. Jonkman JH, Sollie FA, Sauter R, Steinijans VW "The influence of caffeine on the steady-state pharmacokinetics of theophylline." Clin Pharmacol Ther 49 (1991): 248-55
  2. Sato J, Nakata H, Owada E, Kikuta T, Umetsu M, Ito K "Influence of usual intake of dietary caffeine on single-dose kinetics of theophylline in healthy human subjects." Eur J Clin Pharmacol 44 (1993): 295-8
  3. Wohlt PD, Zheng L, Gunderson S, Balzar SA, Johnson BD, Fish JT "Recommendations for the use of medications with continuous enteral nutrition." Am J Health Syst Pharm 66 (2009): 1438-67

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Moderate

perindopril food

Applies to: amlodipine / perindopril

GENERALLY AVOID: Moderate-to-high dietary intake of potassium can cause hyperkalemia in some patients who are using angiotensin converting enzyme (ACE) inhibitors. In some cases, affected patients were using a potassium-rich salt substitute. ACE inhibitors can promote hyperkalemia through inhibition of the renin-aldosterone-angiotensin (RAA) system.

MANAGEMENT: It is recommended that patients who are taking ACE inhibitors be advised to avoid moderately high or high potassium dietary intake. Particular attention should be paid to the potassium content of salt substitutes.

References

  1. "Product Information. Vasotec (enalapril)." Merck & Co., Inc PROD (2002):
  2. Good CB, McDermott L "Diet and serum potassium in patients on ACE inhibitors." JAMA 274 (1995): 538
  3. Ray K, Dorman S, Watson R "Severe hyperkalaemia due to the concomitant use of salt substitutes and ACE inhibitors in hypertension: a potentially life threatening interaction." J Hum Hypertens 13 (1999): 717-20

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Moderate

amLODIPine food

Applies to: amlodipine / perindopril

MONITOR: Many psychotherapeutic and CNS-active agents (e.g., anxiolytics, sedatives, hypnotics, antidepressants, antipsychotics, opioids, alcohol, muscle relaxants) exhibit hypotensive effects, especially during initiation of therapy and dose escalation. Coadministration with antihypertensives and other hypotensive agents, in particular vasodilators and alpha-blockers, may result in additive effects on blood pressure and orthostasis.

MANAGEMENT: Caution and close monitoring for development of hypotension is advised during coadministration of these agents. Some authorities recommend avoiding alcohol in patients receiving vasodilating antihypertensive drugs. Patients should be advised to avoid rising abruptly from a sitting or recumbent position and to notify their physician if they experience dizziness, lightheadedness, syncope, orthostasis, or tachycardia.

References

  1. Sternbach H "Fluoxetine-associated potentiation of calcium-channel blockers." J Clin Psychopharmacol 11 (1991): 390-1
  2. Shook TL, Kirshenbaum JM, Hundley RF, Shorey JM, Lamas GA "Ethanol intoxication complicating intravenous nitroglycerin therapy." Ann Intern Med 101 (1984): 498-9
  3. Feder R "Bradycardia and syncope induced by fluoxetine." J Clin Psychiatry 52 (1991): 139
  4. Ellison JM, Milofsky JE, Ely E "Fluoxetine-induced bradycardia and syncope in two patients." J Clin Psychiatry 51 (1990): 385-6
  5. Rodriguez de la Torre B, Dreher J, Malevany I, et al. "Serum levels and cardiovascular effects of tricyclic antidepressants and selective serotonin reuptake inhibitors in depressed patients." Ther Drug Monit 23 (2001): 435-40
  6. Cerner Multum, Inc. "Australian Product Information." O 0
  7. Pacher P, Kecskemeti V "Cardiovascular side effects of new antidepressants and antipsychotics: new drugs, old concerns?" Curr Pharm Des 10 (2004): 2463-75
  8. Andrews C, Pinner G "Postural hypotension induced by paroxetine." BMJ 316 (1998): 595
View all 8 references

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Moderate

amLODIPine food

Applies to: amlodipine / perindopril

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

  1. Henry M, Kay MM, Viccellio P "Cardiogenic shock associated with calcium-channel and beta blockers: reversal with intravenous calcium chloride." Am J Emerg Med 3 (1985): 334-6
  2. Moller IW "Cardiac arrest following intravenous verapamil combined with halothane anaesthesia." Br J Anaesth 59 (1987): 522-6
  3. Oszko MA, Klutman NE "Use of calcium salts during cardiopulmonary resuscitation for reversing verapamil-associated hypotension." Clin Pharm 6 (1987): 448-9
  4. Schoen MD, Parker RB, Hoon TJ, et al. "Evaluation of the pharmacokinetics and electrocardiographic effects of intravenous verapamil with intravenous calcium chloride pretreatment in normal subjects." Am J Cardiol 67 (1991): 300-4
  5. O'Quinn SV, Wohns DH, Clarke S, Koch G, Patterson JH, Adams KF "Influence of calcium on the hemodynamic and anti-ischemic effects of nifedipine observed during treadmill exercise testing." Pharmacotherapy 10 (1990): 247
  6. Woie L, Storstein L "Successful treatment of suicidal verapamil poisoning with calcium gluconate." Eur Heart J 2 (1981): 239-42
  7. Morris DL, Goldschlager N "Calcium infusion for reversal of adverse effects of intravenous verapamil." JAMA 249 (1983): 3212-3
  8. Guadagnino V, Greengart A, Hollander G, Solar M, Shani J, Lichstein E "Treatment of severe left ventricular dysfunction with calcium chloride in patients receiving verapamil." J Clin Pharmacol 27 (1987): 407-9
  9. Luscher TF, Noll G, Sturmer T, Huser B, Wenk M "Calcium gluconate in severe verapamil intoxication." N Engl J Med 330 (1994): 718-20
  10. Bar-Or D, Gasiel Y "Calcium and calciferol antagonise effect of verapamil in atrial fibrillation." Br Med J (Clin Res Ed) 282 (1981): 1585-6
  11. Lipman J, Jardine I, Roos C, Dreosti L "Intravenous calcium chloride as an antidote to verapamil-induced hypotension." Intensive Care Med 8 (1982): 55-7
  12. McMillan R "Management of acute severe verapamil intoxication." J Emerg Med 6 (1988): 193-6
  13. Perkins CM "Serious verapamil poisoning: treatment with intravenous calcium gluconate." Br Med J 2 (1978): 1127
  14. Moroni F, Mannaioni PF, Dolara A, Ciaccheri M "Calcium gluconate and hypertonic sodium chloride in a case of massive verapamil poisoning." Clin Toxicol 17 (1980): 395-400
View all 14 references

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Moderate

theophylline food

Applies to: ephedrine / phenobarbital / potassium iodide / 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

  1. Jonkman JH, Sollie FA, Sauter R, Steinijans VW "The influence of caffeine on the steady-state pharmacokinetics of theophylline." Clin Pharmacol Ther 49 (1991): 248-55
  2. Sato J, Nakata H, Owada E, Kikuta T, Umetsu M, Ito K "Influence of usual intake of dietary caffeine on single-dose kinetics of theophylline in healthy human subjects." Eur J Clin Pharmacol 44 (1993): 295-8

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Moderate

ePHEDrine food

Applies to: ephedrine / phenobarbital / potassium iodide / theophylline

MONITOR: Coadministration of two or more sympathomimetic agents may increase the risk of adverse effects such as nervousness, irritability, and increased heart rate. Central nervous system (CNS) stimulants, particularly amphetamines, can potentiate the adrenergic response to vasopressors and other sympathomimetic agents. Additive increases in blood pressure and heart rate may occur due to enhanced peripheral sympathetic activity.

MANAGEMENT: Caution is advised if two or more sympathomimetic agents are coadministered. Pulse and blood pressure should be closely monitored.

References

  1. Rosenblatt JE, Lake CR, van Kammen DP, Ziegler MG, Bunney WE Jr "Interactions of amphetamine, pimozide, and lithium on plasma norepineophrine and dopamine-beta-hydroxylase in schizophrenic patients." Psychiatry Res 1 (1979): 45-52
  2. Cavanaugh JH, Griffith JD, Oates JA "Effect of amphetamine on the pressor response to tyramine: formation of p-hydroxynorephedrine from amphetamine in man." Clin Pharmacol Ther 11 (1970): 656
  3. "Product Information. Adderall (amphetamine-dextroamphetamine)." Shire Richwood Pharmaceutical Company Inc PROD (2001):
  4. "Product Information. Tenuate (diethylpropion)." Aventis Pharmaceuticals PROD (2001):
  5. "Product Information. Sanorex (mazindol)." Novartis Pharmaceuticals PROD (2001):
  6. "Product Information. Focalin (dexmethylphenidate)." Mikart Inc (2001):
  7. "Product Information. Strattera (atomoxetine)." Lilly, Eli and Company (2002):
View all 7 references

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Minor

amLODIPine food

Applies to: amlodipine / perindopril

The consumption of grapefruit juice may slightly increase plasma concentrations of amlodipine. The mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. Data have been conflicting and the clinical significance is unknown. Monitoring for calcium channel blocker adverse effects (e.g., headache, hypotension, syncope, tachycardia, edema) is recommended.

References

  1. Bailey DG, Arnold JMO, Spence JD "Grapefruit juice and drugs - how significant is the interaction." Clin Pharmacokinet 26 (1994): 91-8
  2. Josefsson M, Zackrisson AL, Ahlner J "Effect of grapefruit juice on the pharmacokinetics of amlodipine in healthy volunteers." Eur J Clin Pharmacol 51 (1996): 189-93
  3. Bailey DG, Malcolm J, Arnold O, Spence JD "Grapefruit juice-drug interactions." Br J Clin Pharmacol 46 (1998): 101-10
  4. Vincent J, Harris SI, Foulds G, Dogolo LC, Willavize S, Friedman HL "Lack of effect of grapefruit juice on the pharmacokinetics and pharmacodynamics of amlodipine." Br J Clin Pharmacol 50 (2000): 455-63
  5. Josefsson M, Ahlner J "Amlodipine and grapefruit juice." Br J Clin Pharmacol 53 (2002): 405; discussion 406
  6. Kane GC, Lipsky JJ "Drug-grapefruit juice interactions." Mayo Clin Proc 75 (2000): 933-42
View all 6 references

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Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.

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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor 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.
Unknown No interaction information available.

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Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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