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Drug Interactions between pimozide and vasopressin

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

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Interactions between your drugs

Major

vasopressin pimozide

Applies to: vasopressin and pimozide

CONTRAINDICATED: Pimozide can cause dose-related prolongation of the QT interval. Theoretically, coadministration with other agents that can prolong the QT interval may result in additive effects and increased risk of ventricular arrhythmias including torsade de pointes and sudden death. In general, the risk of an individual agent or a combination of agents causing ventricular arrhythmia in association with QT prolongation is largely unpredictable but may be increased by certain underlying risk factors such as congenital long QT syndrome, cardiac disease, and electrolyte disturbances (e.g., hypokalemia, hypomagnesemia). The extent of drug-induced QT prolongation is dependent on the particular drug(s) involved and dosage(s) of the drug(s). In addition, certain agents with anticholinergic properties (e.g., sedating antihistamines; antispasmodics; neuroleptics; phenothiazines; skeletal muscle relaxants; tricyclic antidepressants; disopyramide) may have additive parasympatholytic and central nervous system-depressant effects when used in combination with pimozide. Excessive parasympatholytic effects may include paralytic ileus, hyperthermia, mydriasis, blurred vision, tachycardia, urinary retention, psychosis, and seizures.

MANAGEMENT: Coadministration of pimozide with other drugs that can prolong the QT interval is considered contraindicated.

References (4)
  1. "Product Information. Orap (pimozide)." Gate Pharmaceuticals
  2. Glassman AH, Bigger JT Jr (2001) "Antipsychotic drugs: prolonged QTc interval, torsade de pointes, and sudden death." Am J Psychiatry, 158, p. 1774-82
  3. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  4. EMA. European Medicines Agency. European Union (2013) EMA - List of medicines under additional monitoring. http://www.ema.europa.eu/ema/index.jsp?curl=pages/regulation/document_listing/document_listing_000366.jsp&mid=WC0b01ac058067c852

Drug and food interactions

Major

pimozide food

Applies to: pimozide

GENERALLY AVOID: Theoretically, the coadministration with grapefruit juice may increase the plasma concentrations of pimozide. The mechanism is decreased clearance of pimozide due to inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. The use of pimozide alone has been associated with dose-dependent prolongation of the QT interval. Although clinical data are lacking, this interaction may result in potentiation of the proarrhythmic effect of pimozide and consequently an increased risk of ventricular arrhythmias such as ventricular tachycardia and torsade de pointes. In addition, alcohol may potentiate some of the pharmacologic effects of pimozide. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

MANAGEMENT: The manufacturer recommends avoiding grapefruit juice (and probably grapefruits) during therapy with pimozide. Patients should also be advised to avoid or limit consumption of alcohol.

References (2)
  1. "Product Information. Orap (pimozide)." Gate Pharmaceuticals
  2. Dresser GK, Spence JD, Bailey DG (2000) "Pharmacokinetic-pharmacodynamic consequences and clinical relevance of cytochrome P450 3A4 inhibition." Clin Pharmacokinet, 38, p. 41-57
Moderate

vasopressin food

Applies to: vasopressin

MONITOR: Alcohol may decrease the antidiuretic effect of vasopressin. Clinical studies found that plasma vasopressin levels often decrease during alcohol consumption and increase upon cessation of consumption. In addition, alcoholics were found to have a more pronounced decrease in plasma vasopressin levels when drinking and suppressed vasopressin levels even during alcohol withdrawal as compared to non-alcoholic individuals. The mechanism of this interaction is not fully understood.

MANAGEMENT: Patients should be advised to abstain from alcohol during vasopressin treatment. Hemodynamic monitoring is suggested for patients known to drink alcohol while receiving vasopressin.

References (7)
  1. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  2. Cerner Multum, Inc. "Australian Product Information."
  3. (2017) "Product Information. Vasostrict (vasopressin)." Par Pharmaceutical Inc
  4. Taivainen H, Laitinen K, Tahtela R, Kilanmaa K, Valimaki MJ (1995) "Role of plasma vasopressin in changes of water balance accompanying acute alcohol intoxication." Alcohol Clin Exp Res, 19, p. 759-62
  5. Collins GB, Brosnihan KB, Zuti RA, Messina M, Gupta MK (1992) "Neuroendocrine, fluid balance, and thirst responses to alcohol in alcoholics." Alcohol Clin Exp Res, 16, p. 228-32
  6. Hirschl MM, Derfler K, Bieglmayer C, et al. (1994) "Hormonal derangements in patients with severe alcohol intoxication." Alcohol Clin Exp Res, 18, p. 761-6
  7. Harper KM, Knapp DJ, Criswell HE, Breese GR (2018) "Vasopressin and alcohol: A multifaceted relationship." Psychopharmacology (Berl), 235, p. 3363-79

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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