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Drug Interactions between chlorpromazine and Mylanta Tonight

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

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Interactions between your drugs

Moderate

chlorproMAZINE magnesium hydroxide

Applies to: chlorpromazine and Mylanta Tonight (calcium carbonate / magnesium hydroxide / simethicone)

MONITOR: Overuse of certain laxatives including magnesium hydroxide may cause electrolyte loss and increase the risk of torsade de pointes ventricular arrhythmia in patients treated with drugs that prolong the QT interval. Electrolyte disturbances including hypokalemia and hypomagnesemia have been reported with laxative abuse and are known risk factors for torsade de pointes associated with QT interval prolongation.

ADJUST DOSING INTERVAL: Coadministration with aluminum- or magnesium-containing antacids may decrease the serum concentrations of orally administered phenothiazines. The proposed mechanism is antacid adsorption resulting in reduced phenothiazine bioavailability. The interaction has been reported for chlorpromazine but may occur with other phenothiazines. In a study of ten patients treated with chlorpromazine, 30 mL of an antacid containing aluminum and magnesium hydroxide reduced the urinary excretion of chlorpromazine by 10% to 45%. In another study with six psychiatric patients, coadministration of chlorpromazine oral suspension with 30 mL of an antacid containing aluminum hydroxide and magnesium trisilicate resulted in a 20% reduction in serum chlorpromazine level two hours later. The clinical significance is unknown. Psychiatric relapse occurred in a chlorpromazine-treated patient following the addition of antacid therapy according to a single case report. Separating the times of administration by 2 to 3 hours may help if an interaction is suspected.

MANAGEMENT: Patients treated with drugs that prolong the QT interval should exercise caution when self-medicating with laxatives including magnesium hydroxide. The recommended dosage and duration of use should not be exceeded. Patients should be advised to seek prompt medical attention if they experience symptoms that could indicate the occurrence of torsade de pointes such as dizziness, lightheadedness, fainting, palpitation, irregular heart rhythm, shortness of breath, or syncope.

References

  1. Fann WE "Interactions of psychotropic drugs in the elderly." Postgrad Med 53 (1973): 182-6
  2. Romankiewicz JA "Effects of antacids on gastrointestinal absorption of drugs." Prim Care 3 (1976): 537-50
  3. Forrest FM, Forrest IS, Serra MT "Modification of chlorpromazine metabolism by some other drugs frequently administered to psychiatric patients." Biol Psychiatry 2 (1970): 53-8
  4. Fann WE, Davis JM, Janowsky DS, Sekerke HJ, Schmidt DM "Chlorpromazine: effects of antacids on its gastrointestinal absorption." J Clin Pharmacol 13 (1973): 388-90
  5. Covington TR, eds., Lawson LC, Young LL "Handbook of Nonprescription Drugs." Washington, DC: American Pharmaceutical Association (1993):
  6. Chin RL "Laxative-induced hypokalemia." Ann Emerg Med 32 (1998): 517-8
  7. Muller-Lissner SA "Adverse effects of laxatives: fact and fiction." Pharmacology 47 (1993): 138-45
  8. Schaefer DC, Cheskin LJ "Constipation in the elderly." Am Fam Physician 58 (1998): 907-14
View all 8 references

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Drug and food interactions

Moderate

calcium carbonate food

Applies to: Mylanta Tonight (calcium carbonate / magnesium hydroxide / simethicone)

ADJUST DOSING INTERVAL: Administration with food may increase the absorption of calcium. However, foods high in oxalic acid (spinach or rhubarb), or phytic acid (bran and whole grains) may decrease calcium absorption.

MANAGEMENT: Calcium may be administered with food to increase absorption. Consider withholding calcium administration for at least 2 hours before or after consuming foods high in oxalic acid or phytic acid.

References

  1. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  2. Canadian Pharmacists Association "e-CPS. http://www.pharmacists.ca/function/Subscriptions/ecps.cfm?link=eCPS_quikLink" (2006):
  3. Cerner Multum, Inc. "Australian Product Information." O 0
  4. Agencia Española de Medicamentos y Productos Sanitarios Healthcare "Centro de información online de medicamentos de la AEMPS - CIMA. https://cima.aemps.es/cima/publico/home.html" (2008):
  5. Mangels AR "Bone nutrients for vegetarians." Am J Clin Nutr 100 (2014): epub
  6. Davies NT "Anti-nutrient factors affecting mineral utilization." Proc Nutr Soc 38 (1979): 121-8
View all 6 references

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Moderate

chlorproMAZINE food

Applies to: 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 "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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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.

Further information

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