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Drug Interactions between atorvastatin / ezetimibe and ephedrine / phenobarbital / theophylline

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

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Interactions between your drugs

Moderate

theophylline PHENobarbital

Applies to: ephedrine / phenobarbital / theophylline and ephedrine / phenobarbital / 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 atorvastatin

Applies to: ephedrine / phenobarbital / theophylline and atorvastatin / ezetimibe

MONITOR: Coadministration with inducers of CYP450 3A4 may decrease the plasma concentrations of atorvastatin and its active metabolites, all of which are substrates of the isoenzyme. When atorvastatin (40 mg/day) was coadministered for 28 days with the potent CYP450 3A4 inducer phenytoin (4 mg/kg/day) in healthy volunteers (n=44), atorvastatin peak plasma concentration (Cmax) and systemic exposure (AUC) decreased by an average of 24% and 54%, respectively. The Cmax of two active metabolites, 2-hydroxy- and 4-hydroxyatorvastatin, also decreased by an average of 22% and 52%, respectively, while AUC decreased by an average of 53% and 44%, respectively. Consistent with the observed pharmacokinetic interaction, there have been isolated reports of reduced efficacy of atorvastatin in the presence of phenytoin, followed by improved cholesterol levels after discontinuation of phenytoin. In another study, coadministration of the mixed CYP450 3A4 inducer/inhibitor efavirenz (600 mg once daily for 15 days) with atorvastatin (10 mg daily during the last 4 days of efavirenz) in 14 healthy volunteers resulted in median decreases of 43% in atorvastatin AUC and 34% in total active atorvastatin (parent drug + active metabolites) AUC. However, the median LDL decrease was not significantly different during coadministration with efavirenz compared to atorvastatin administered alone (-29 versus -22, respectively). Atorvastatin did not affect the AUC of efavirenz. In a study of patients with non-small cell lung cancer receiving the CYP450 3A4 inducer bexarotene (400 mg/m2 orally once a day) plus either paclitaxel/carboplatin or cisplatin/vinorelbine chemotherapy, treatment with atorvastatin or fenofibrate was given to manage bexarotene-induced hyperlipidemia. Investigators reported that bexarotene decreased mean atorvastatin systemic exposure (dose-corrected AUC) by approximately 50%, whereas atorvastatin had no significant effect on bexarotene plasma concentrations. In 16 study subjects administered etravirine with atorvastatin 40 mg once a day, atorvastatin AUC decreased by 37%, while Cmax and AUC of 2-hydroxy-atorvastatin increased by 76% and 27%, respectively. Atorvastatin did not significantly affect the pharmacokinetics of etravirine.

MANAGEMENT: The potential for diminished pharmacologic effects of atorvastatin should be considered during coadministration with CYP450 3A4 inducers. Alternative agents with no or minimal CYP450 3A4 induction potential are recommended whenever possible. Otherwise, pharmacologic response to atorvastatin should be closely monitored, and the dosage adjusted as necessary. A statin that is not metabolized by CYP450 3A4 such as fluvastatin, pitavastatin, pravastatin, or rosuvastatin may also be substituted for atorvastatin when used with certain enzyme inducers.

References

  1. "Product Information. Lipitor (atorvastatin)." Parke-Davis PROD (2001):
  2. Murphy MJ, Dominiczak MH "Efficacy of statin therapy: possible effect of phenytoin." Postgrad Med J 75 (1999): 359-60
  3. Gerber JG, Rosenkranz SL, Fichtenbaum CJ, et al. "Effect of efavirenz on the pharmacokinetics of simvastatin, atorvastatin, and pravastatin: results of AIDS Clinical Trials Group 5108 Study." J Acquir Immune Defic Syndr 39 (2005): 307-12
  4. Khandwala HM "Lipid lowering inefficacy of high-dose statin therapy due to concurrent use of phenytoin." South Med J 99 (2006): 1385-7
  5. Bullman J, Nicholls A, Van Landingham K, et al. "Effects of lamotrigine and phenytoin on the pharmacokinetics of atorvastatin in healthy volunteers." Epilepsia 52 (2011): 1351-8
View all 5 references

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Moderate

atorvastatin ezetimibe

Applies to: atorvastatin / ezetimibe and atorvastatin / ezetimibe

MONITOR: Coadministration with ezetimibe may rarely increase the risk of myopathy and serum transaminase elevations associated with HMG-CoA reductase inhibitors (i.e., statins). The mechanism of interaction is unknown. A case report describes two patients whose serum creatine kinase increased after ezetimibe was added to their statin therapy (atorvastatin and fluvastatin, respectively). One of the patients also developed myalgia and tendinopathy, which resolved promptly after withdrawal of both drugs. Statin therapy was subsequently reintroduced at the previous dosage without incident. In the other patient, serum creatine kinase returned to normal within 4 weeks after discontinuation of ezetimibe while the statin was continued. On the contrary, no cases of myopathy or tendinopathy occurred in a study of 33 hypercholesterolemic patients treated with ezetimibe and atorvastatin or simvastatin. There were also no reports of myopathy or significant increases in serum creatine kinase in a study of 32 subjects treated with ezetimibe and fluvastatin. In controlled clinical studies, the incidence of consecutive elevations (greater than 3 times the upper limit of normal) in serum transaminases was 1.3% for patients treated with ezetimibe in combination with a statin versus 0.4% for patients treated with a statin alone. These elevations were generally asymptomatic, not associated with cholestasis, and returned to baseline after discontinuation of therapy or with continued treatment.

MANAGEMENT: Until further information is available, use of a statin in combination with ezetimibe should be approached with caution. Patients should be advised to promptly report to their physician any unexplained muscle pain, tenderness, or weakness, particularly if accompanied by malaise or fever. The drugs should be discontinued if creatine kinase is markedly elevated in the absence of strenuous exercise or if myopathy is otherwise suspected or diagnosed. In addition, liver function tests should be performed at initiation of therapy and according to the recommendations of the HMG-CoA reductase inhibitor.

References

  1. Gagne C, Gaudet D, Bruckert E "Efficacy and safety of ezetimibe coadministered with atorvastatin or simvastatin in patients with homozygous familial hypercholesterolemia." Circulation 105 (2002): 2469-75
  2. Fux R, Morike K, Gundel UF, Hartmann R, Gleiter CH "Ezetimibe and statin-associated myopathy." Ann Intern Med 140 (2004): 671-2

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Minor

theophylline ePHEDrine

Applies to: ephedrine / phenobarbital / theophylline and ephedrine / phenobarbital / 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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Drug and food interactions

Major

PHENobarbital food

Applies to: ephedrine / phenobarbital / 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 / 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

atorvastatin food

Applies to: atorvastatin / ezetimibe

GENERALLY AVOID: Coadministration with grapefruit juice may increase the plasma concentrations of atorvastatin. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. When a single 40 mg dose of atorvastatin was coadministered with 240 mL of grapefruit juice, atorvastatin peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 16% and 37%, respectively. Greater increases in Cmax (up to 71%) and/or AUC (up to 2.5 fold) have been reported with excessive consumption of grapefruit juice (>=750 mL to 1.2 liters per day). Clinically, high levels of HMG-CoA reductase inhibitory activity in plasma is associated with an increased risk of musculoskeletal toxicity. Myopathy manifested as muscle pain and/or weakness associated with grossly elevated creatine kinase exceeding ten times the upper limit of normal has been reported occasionally. Rhabdomyolysis has also occurred rarely, which may be accompanied by acute renal failure secondary to myoglobinuria and may result in death.

ADJUST DOSING INTERVAL: Fibres such as oat bran and pectin may diminish the pharmacologic effects of HMG-CoA reductase inhibitors by interfering with their absorption from the gastrointestinal tract.

MANAGEMENT: Patients receiving therapy with atorvastatin should limit their consumption of grapefruit juice to no more than 1 liter per day. Patients should be advised to promptly report any unexplained muscle pain, tenderness or weakness, particularly if accompanied by fever, malaise and/or dark colored urine. Therapy should be discontinued if creatine kinase is markedly elevated in the absence of strenuous exercise or if myopathy is otherwise suspected or diagnosed. In addition, patients should either refrain from the use of oat bran and pectin or, if concurrent use cannot be avoided, to separate the administration times by at least 2 to 4 hours.

References

  1. Richter WO, Jacob BG, Schwandt P "Interaction between fibre and lovastatin." Lancet 338 (1991): 706
  2. McMillan K "Considerations in the formulary selection of hydroxymethylglutaryl coenzyme a reductase inhibitors." Am J Health Syst Pharm 53 (1996): 2206-14
  3. "Product Information. Lipitor (atorvastatin)." Parke-Davis PROD (2001):
  4. Boberg M, Angerbauer R, Fey P, Kanhai WK, Karl W, Kern A, Ploschke J, Radtke M "Metabolism of cerivastatin by human liver microsomes in vitro. Characterization of primary metabolic pathways and of cytochrome P45 isozymes involved." Drug Metab Dispos 25 (1997): 321-31
  5. Bailey DG, Malcolm J, Arnold O, Spence JD "Grapefruit juice-drug interactions." Br J Clin Pharmacol 46 (1998): 101-10
  6. Lilja JJ, Kivisto KT, Neuvonen PJ "Grapefruit juice increases serum concentrations of atorvastatin and has no effect on pravastatin." Clin Pharmacol Ther 66 (1999): 118-27
  7. Neuvonen PJ, Backman JT, Niemi M "Pharmacokinetic comparison of the potential over-the-counter statins simvastatin, lovastatin, fluvastatin and pravastatin." Clin Pharmacokinet 47 (2008): 463-74
View all 7 references

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Moderate

theophylline food

Applies to: ephedrine / phenobarbital / 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 / 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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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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