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Drug Interactions between P2E1 and Promethazine VC Plain

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

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Interactions between your drugs

Moderate

promethazine pilocarpine ophthalmic

Applies to: Promethazine VC Plain (phenylephrine / promethazine) and P2E1 (epinephrine / pilocarpine ophthalmic)

MONITOR: Theoretically, anticholinergic agents and other agents with significant anticholinergic activity (e.g., antihistamines, antispasmodics, neuroleptics, phenothiazines, skeletal muscle relaxants, tricyclic antidepressants, class IA antiarrhythmics especially disopyramide) may antagonize the effects of topically administered cholinergic agents such as acetylcholine, carbachol, demecarium, echothiophate, isoflurophate, physostigmine, and pilocarpine. The proposed mechanism involves opposing pharmacodynamic action on muscarinic receptor sites in ocular tissue. This interaction is sometimes desirable and is the basis for using atropine in the treatment of excessive muscarinic side effects and cholinergic crisis induced by cholinergic overdose.

MANAGEMENT: Patients receiving long-term therapy with anticholinergic agents should be monitored for potentially diminished therapeutic (miotic) response to ophthalmic cholinergic therapy, and dosages adjusted as necessary.

References

  1. "Multum Information Services, Inc. Expert Review Panel"
  2. "Product Information. Pilopine-HS (pilocarpine ophthalmic)." Alcon Laboratories Inc PROD

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Drug and food interactions

Moderate

promethazine food

Applies to: Promethazine VC Plain (phenylephrine / promethazine)

GENERALLY AVOID: Concurrent use of ethanol and phenothiazines may result in additive CNS depression and psychomotor impairment. Also, ethanol may precipitate dystonic reactions in patients who are taking phenothiazines. The two drugs probably act on different sites in the brain, although the exact mechanism of the interaction is not known.

MANAGEMENT: Patients should be advised to avoid alcohol during phenothiazine therapy.

References

  1. Lutz EG "Neuroleptic-induced akathisia and dystonia triggered by alcohol." JAMA 236 (1976): 2422-3
  2. Freed E "Alcohol-triggered-neuroleptic-induced tremor, rigidity and dystonia." Med J Aust 2 (1981): 44-5

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Moderate

phenylephrine food

Applies to: Promethazine VC Plain (phenylephrine / promethazine)

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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