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Drug Interactions between Inderal LA and Ormazine

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

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Interactions between your drugs

Moderate

propranolol chlorproMAZINE

Applies to: Inderal LA (propranolol) and Ormazine (chlorpromazine)

MONITOR: Some antipsychotic agents and some beta-blockers may mutually inhibit each other's metabolism resulting in increased or additive pharmacologic effects such as hypotension, bradycardia, delirium or seizures. The mechanism may be related to competitive inhibition of CYP450 2D6-mediated first-pass metabolism.

MANAGEMENT: Atenolol, carteolol, or nadolol may be considered as alternatives because they undergo renal elimination and are not expected to interact. If this combination cannot be avoided, decreased dosage of either or both drugs may be necessary and the patient should be closely monitored for cardiovascular or nervous system adverse effects.

References

  1. Peet M, Middlemiss D, Yates R (1980) "Pharmacokinetic interaction between propranolol and chlorpromazine in schizophrenic patients." Lancet, 2, p. 978
  2. Miller F, Rampling D (1982) "Adverse effects of combined propranolol and chlorpromazine therapy." Am J Psychiatry, 139, p. 1198-9
  3. Silver JM, Yudofsky SC, Kogan M, Katz BL (1986) "Elevation of thioridazine plasma levels by propranolol." Am J Psychiatry, 143, p. 1290-2
  4. Vestal RE, Kornhauser DM, Hollifield JW, Shand DG (1979) "Inhibition of propranolol metabolism by chlorpromazine." Clin Pharmacol Ther, 25, p. 19-24
  5. Markowitz JS, Wells BG, Carson WH (1995) "Interactions between antipsychotic and antihypertensive drugs." Ann Pharmacother, 29, p. 603-9
View all 5 references

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Drug and food interactions

Moderate

propranolol food

Applies to: Inderal LA (propranolol)

ADJUST DOSING INTERVAL: The bioavailability of propranolol may be enhanced by food.

MANAGEMENT: Patients may be instructed to take propranolol at the same time each day, preferably with or immediately following meals.

References

  1. Olanoff LS, Walle T, Cowart TD, et al. (1986) "Food effects on propranolol systemic and oral clearance: support for a blood flow hypothesis." Clin Pharmacol Ther, 40, p. 408-14
  2. Byrne AJ, McNeil JJ, Harrison PM, Louis W, Tonkin AM, McLean AJ (1984) "Stable oral availability of sustained release propranolol when co-administered with hydralazine or food: evidence implicating substrate delivery rate as a determinant of presystemic drug interactions." Br J Clin Pharmacol, 17, s45-50

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Moderate

chlorproMAZINE food

Applies to: Ormazine (chlorpromazine)

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

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Moderate

propranolol food

Applies to: Inderal LA (propranolol)

ADJUST DOSING INTERVAL: Concurrent administration with calcium salts may decrease the oral bioavailability of atenolol and possibly other beta-blockers. The exact mechanism of interaction is unknown. In six healthy subjects, calcium 500 mg (as lactate, carbonate, and gluconate) reduced the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of atenolol (100 mg) by 51% and 32%, respectively. The elimination half-life increased by 44%. Twelve hours after the combination, beta-blocking activity (as indicated by inhibition of exercise tachycardia) was reduced compared to that with atenolol alone. However, during a 4-week treatment in six hypertensive patients, there was no difference in blood pressure values between treatments. The investigators suggest that prolongation of the elimination half-life induced by calcium coadministration may have led to atenolol cumulation during long-term dosing, which compensated for the reduced bioavailability.

MANAGEMENT: It may help to separate the administration times of beta-blockers and calcium products by at least 2 hours. Patients should be monitored for potentially diminished beta-blocking effects following the addition of calcium therapy.

References

  1. Kirch W, Schafer-Korting M, Axthelm T, Kohler H, Mutschler E (1981) "Interaction of atenolol with furosemide and calcium and aluminum salts." Clin Pharmacol Ther, 30, p. 429-35

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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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