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Drug Interactions between Purge and quinine

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

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Interactions between your drugs

Moderate

quiNINE castor oil

Applies to: quinine and Purge (castor oil)

MONITOR: Bowel cleansing as well as overuse of certain laxatives 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.

MANAGEMENT: Patients treated with drugs that prolong the QT interval should exercise caution when self-medicating with laxatives. The recommended dosage and duration of use should not be exceeded. Patients treated with lactulose for more than six months should be monitored periodically for electrolyte imbalance. 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. Chin RL (1998) "Laxative-induced hypokalemia." Ann Emerg Med, 32, p. 517-8
  2. Muller-Lissner SA (1993) "Adverse effects of laxatives: fact and fiction." Pharmacology, 47, p. 138-45
  3. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  4. Canadian Pharmacists Association (2006) e-CPS. http://www.pharmacists.ca/function/Subscriptions/ecps.cfm?link=eCPS_quikLink
  5. Cerner Multum, Inc. "Australian Product Information."
  6. Schaefer DC, Cheskin LJ (1998) "Constipation in the elderly." Am Fam Physician, 58, p. 907-14
View all 6 references

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Drug and food interactions

Minor

quiNINE food

Applies to: quinine

Coadministration with grapefruit juice does not appear to affect the pharmacokinetics of quinine in a clinically relevant manner. Although grapefruit juice is an inhibitor of CYP450 3A4 and quinine is metabolized by this pathway to its major metabolite, 3-hydroxyquinine, a study of ten healthy volunteers found no significant differences in quinine peak plasma concentration (Cmax), time to reach Cmax (Tmax), terminal elimination half-life, systemic exposure (AUC), or apparent oral clearance (Cl/F) when a single 600 mg oral dose of quinine sulfate was administered in combination with 200 mL of orange juice (control), half-strength grapefruit juice, and full-strength grapefruit juice twice daily for 6 days each, separated by a 2-week washout period. Relative to the control period, the apparent renal clearance of quinine was markedly increased by 81% during treatment with half-strength grapefruit juice. However, since renal clearance accounts for approximately 6% of the total clearance of quinine, this change would likely have minimal clinical impact. The lack of a significant interaction is probably due to the fact that grapefruit juice primarily inhibits intestinal rather than hepatic CYP450 3A4, and quinine is not known to undergo significant presystemic metabolism as evidenced by its relatively high oral bioavailability (76% to 88%). Nevertheless, excessive consumption of grapefruit juice and tonic water (which contains quinine) was suspected as the cause of torsade de pointes arrhythmia in a patient with a history of asymptomatic long QT syndrome. Treatment with magnesium sulfate and metoprolol had no effect, but the arrhythmia resolved spontaneously 48 hours after discontinuation of the drinks. Based on current data, moderate grapefruit juice consumption is probably safe for the majority of patients taking quinine.

References

  1. Ho PC, Chalcroft SC, Coville PF, Wanwimolruk S (1999) "Grapefruit juice has no effect on quinine pharmacokinetics." Eur J Clin Pharmacol, 55, p. 393-8
  2. Hermans K, Stockman D, Van den Branden F (2003) "Grapefruit and tonic: a deadly combination in a patient with the long QT syndrome." Am J Med, 114, p. 511-2
  3. (2006) "Product Information. Qualaquin (quinine)." AR Scientific Inc
  4. Zhang H, Coville PF, Walker RJ, Miners JO, Birkett DJ, Wanwimolruk S (1997) "Evidence for involvement of human CYP3A in the 3-hydroxylation of quinine." Br J Clin Pharmacol, 43, p. 245-52
  5. Mirghani RA, Yasar U, Zheng T, et al. (2002) "Enzyme kinetics for the formation of 3-hydroxyquinine and three new metabolites of quinine in vitro; 3-hydroxylation by CYP3A4 is indeed the major metabolic pathway." Drug Metab Dispos, 30, p. 1368-71
View all 5 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.


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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.