Drug
Clozapine
Pronounced
"KLO-zuh-peen"
Drug Interactions
Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.
A product that may interact with this drug is: metoclopramide.
Other medications can affect the removal of clozapine from your body, which may affect how clozapine works. Examples include fluvoxamine, St. John's wort, drugs used to treat seizures (such as carbamazepine, phenytoin), among others.
Tell your doctor or pharmacist if you are taking other products that cause drowsiness such as opioid pain or cough relievers (such as codeine, hydrocodone), alcohol, marijuana (cannabis), drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or antihistamines (such as cetirizine, diphenhydramine).
Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about using those products safely.
Cigarette smoking decreases blood levels of this medication. Tell your doctor if you smoke or if you have recently stopped smoking.
Negative Interactions
2- Potential Negative Interaction
Clozapine
Foods with Caffeine
Caffeine is a compound found in coffee, colas, and tea, as well as in some over-the-counter products. One 31-year-old woman taking clozapine who consumed nearly 1,000 mg of caffeine daily experienced side effects from the drug. A subsequent study involving individuals with schizophrenia who were stabilized on clozapine, showed that caffeine avoidance resulted in significantly lower blood levels of the drug. Controlled research is needed to determine whether problems might occur when individuals taking clozapine change the amount of caffeine they consume each day. Until more information is available, individuals taking clozapine should talk with their healthcare practitioner before making changes in their caffeine intake.
Foods with CaffeineClozapine- Wetzel H, Anghelescu I, Szegedi A, et al. Pharmacokinetic interactions of clozapine with selective serotonin reuptake: differential effects of fluvoxamine and paroxetine in a prospective study. J Clin Psychopharmacol 1998;18:2-9.
- Odom-White A, deLeon J. Clozapine levels and caffeine. J Clin Psychiatry 1996;57:175-6.
- Reduces Effectiveness
Clozapine
Glycine
This interaction is based on this drug belonging to a drug class. While this drug may differ from the text and references below, drugs within this class work in a similar way and this interaction is applicable to drugs within the same class.
The use of glycine may interfere with the efficacy of clozapine as an antipsychotic drug. In a double-blind trial, people with chronic, treatment-resistant schizophrenia were given clozapine (400–1,200 mg per day) and either glycine (30 g per day) or placebo for 12 weeks. The combination of clozapine and glycine was not effective at decreasing symptoms. In contrast, participants who took clozapine without glycine had a 35% reduction in some symptoms. Therefore, the combination should be avoided until more is known.
GlycineClozapine- Potkin SG, Jin Y, Bunney BG, et al. Effect of clozapine and adjunctive high-dose glycine in treatment-resistant schizophrenia. Am J Psychiatry 1999;156:145-7.
Supportive Interactions
6- Replenish Depleted Nutrients
Clozapine
L-Tryptophan
Some people who take clozapine become mentally depressed after taking the drug for a few weeks. Studies have shown that clozapine can reduce blood levels of the amino acid L-tryptophan, which is often deficient in people with depression. More controlled research is needed to determine whether the interaction is significant and whether individuals taking clozapine might benefit from supplemental L-tryptophan or 5-hydroxytryptophan (5-HTP).
L-TryptophanClozapine- Meltzer HY. Clinical studies on the mechanism of action of clozapine: the dopamine-serotonin hypothesis of schizophrenia. Psychopharmacology 1989;99 Suppl:S18-27 (Berlin).
- Replenish Depleted Nutrients
Clozapine
Selenium
One controlled study showed that taking clozapine can decrease blood levels of selenium, a mineral with antioxidant activity. While more research is needed to determine whether people taking clozapine might require selenium supplementation, until more information is available, some health practitioners recommend supplementation.
SeleniumClozapine- Williams DP, Pirmohamed M, Naisbitt DJ, et al. Neutrophil cytotoxicity of the chemically reactive metabolite(s) of clozapine: possible role in agranulocytosis. J Pharmacol Exp Ther 1997;283:1375-82.
- Support Medicine
Clozapine
Ginkgo
In one study, treatment with 120 mg per day of Ginkgo biloba extract for 12 weeks enhanced the beneficial effect of clozapine on certain symptoms of schizophrenia in patients who had not responded adequately to clozapine by itself.GinkgoClozapine- Doruk A, Uzun O, Ozsahin A. A placebo-controlled study of extract of ginkgo biloba added to clozapine in patients with treatment-resistant schizophrenia. Int Clin Psychopharmacol 2008;23:223-7.
- Support Medicine
Clozapine
Glycine
This interaction is based on this drug belonging to a drug class. While this drug may differ from the text and references below, drugs within this class work in a similar way and this interaction is applicable to drugs within the same class.
In a small double-blind study, people with schizophrenia being treated with risperidone experienced an improvement in their symptoms when glycine was added to their treatment regimen. The initial amount of glycine used was 4 grams per day; this was increased gradually over a period of 10 to 17 days to a maximum of 0.8 grams per 2.2 pounds of body weight per day.
GlycineClozapine- Heresco-Levy U, Ermilov M, Lichtenberg P, et al. High-dose glycine added to olanzapine and risperidone for the treatment of schizophrenia. Biol Psychiatry 2004;55:165-71.
- Reduce Side Effects
Clozapine
N-Acetyl Cysteine
Clozapine can inhibit the formation of immune cells that protect the body from invading organisms. Test tube studies show that N-acetyl-cysteine and vitamin C block the formation of immune cell–damaging compounds produced when clozapine is broken down. Controlled studies are necessary to determine whether supplementing N-acetyl-cysteine and vitamin C might prevent harmful side effects in people taking clozapine.
N-Acetyl CysteineClozapine- Linday LA, Pippenger CE, Howard A, Lieberman JA. Free radical scavenging enzyme activity and related trace metals in clozapine-induced agranulocytosis: a pilot study. J Clin Psychopharmacol 1995;15:353-60.
- Reduce Side Effects
Clozapine
Vitamin C
Clozapine can inhibit the formation of immune cells that protect the body from invading organisms. Test tube studies show that N-acetyl-cysteine and vitamin C block the formation of immune cell–damaging compounds produced when clozapine is broken down. Controlled studies are necessary to determine whether supplementing N-acetyl-cysteine and vitamin C might prevent harmful side effects in people taking clozapine.
Vitamin CClozapine- Linday LA, Pippenger CE, Howard A, Lieberman JA. Free radical scavenging enzyme activity and related trace metals in clozapine-induced agranulocytosis: a pilot study. J Clin Psychopharmacol 1995;15:353-60.