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Drug Interactions between hydroxypropyl chitosan / terbinafine topical and Phyllocontin

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

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Interactions between your drugs

Moderate

aminophylline terbinafine

Applies to: Phyllocontin (aminophylline) and hydroxypropyl chitosan / terbinafine topical

MONITOR: The coadministration of terbinafine and theophylline may result in elevated plasma concentrations of the latter. In a randomized, crossover study consisting of 12 healthy volunteers, terbinafine (250 mg orally once a day for 4 days) increased the area under the serum concentration-time curve (AUC) and half-life of a single dose of theophylline (5 mg/kg) by 16% and 24%, respectively, compared to placebo. Oral clearance decreased by 14%. The exact mechanism is unknown but may involve inhibition of the CYP450 1A2 enzymatic pathway, which is responsible for the metabolism of theophylline and other methylxanthines such as caffeine, the clearance of which has also been found to be reduced (21%) by terbinafine.

MANAGEMENT: Given the narrow therapeutic index of theophylline, patients should be monitored closely during concomitant therapy with terbinafine. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate whenever terbinafine is added to or withdrawn from therapy. Due to the long elimination half-life of terbinafine, especially following prolonged use, potential drug interactions may be observed for several months after discontinuation of terbinafine therapy. Patients should be advised to report any signs of theophylline toxicity including nausea, vomiting, diarrhea, headache, restlessness, insomnia, or irregular heartbeat to their physicians.

References

  1. Wahllander A, Paumgartner G "Effect of ketoconazole and terbinafine on the pharmacokinetics of caffeine in healthy volunteers." Eur J Clin Pharmacol 37 (1989): 279-83
  2. Trepanier EF, Nafziger AN, Amsden GW "Effect of terbinafine on theophylline pharmacokinetics in healthy volunteers." Antimicrob Agents Chemother 42 (1998): 695-7

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Drug and food interactions

Moderate

aminophylline food

Applies to: Phyllocontin (aminophylline)

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.

See also

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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.

Further information

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

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