Thioridazine

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Also indexed as: Apo-Thioridazine, Mellaril, Melleril, Rideril

Thioridazine is used to treat symptoms associated with psychosis; depression with worry and restlessness in adults; irritability, worry, and fear in elderly; and severe behavioural problems in children, including fighting and hyperactivity. It is classified as a phenothiazine neuroleptic.

Summary of Interactions with Vitamins, Herbs, and Foods
In some cases, a herb or supplement may appear in more than one category, which may seem contradictory. For clarification, read the full article for details about the summarized interactions.

May Be Beneficial: Depletion or interference—The medication may deplete or interfere with the absorption or function of the nutrient. Taking these nutrients may help replenish them.	Vitamin A
May Be Beneficial: Side effect reduction/prevention—Taking these supplements may help reduce the likelihood and/or severity of a potential side effect caused by the medication.	Co-Enzyme Q10 Potassium*
May Be Beneficial: Supportive interaction—Taking these supplements may support or otherwise help your medication work better.	Niacin*
Avoid: Adverse interaction—Avoid these supplements when taking this medication because taking them together may cause undesirable or dangerous results.	Bacopa Lithium*
Check: Other—Before taking any of these supplements or eating any of these foods with your medication, read this article in full for details.	Vitamin C*
Reduced drug absorption/bioavailability	None known

An asterisk (*) next to an item in the summary indicates that the interaction is supported only by weak, fragmentary, and/or contradictory scientific evidence.

Interactions with Dietary Supplements

Vitamin A
A review of people taking thioridazine showed that they had higher blood levels of vitamin A than did individuals not using the drug.¹ More research is necessary to determine whether taking vitamin A supplements with thioridazine might cause dangerously high vitamin A levels. Until more is known, people taking thioridazine should exercise caution with vitamin A supplementation and be alert for side effects such as bone pain, headaches, dry scaly skin, and hair loss.

Potassium
Some people taking thioridazine experience changes in the electrical activity of the heart, which sometimes improve with potassium supplementation.² More research is needed to determine if people taking thioridazine might prevent heart problems by supplementing with potassium.

Niacin (nicotinic acid)
In a controlled study, individuals taking thioridazine for psychosis cooperated better and withdrew less from other people when niacin, 300–1,500 mg each day, was added.³ Whether people who are taking thioridazine for other mental health problems might benefit from niacin supplementation is unknown.

Co-Enzyme Q10
Phenothiazine drugs like thioridazine can cause changes in heart activity in some people, which might be prevented with co-Enzyme Q10 supplementation.⁴ Therefore, some doctors and pharmacists may recommend co-Enzyme Q10 supplements to individuals taking thioridazine.

Lithium
Lithium is a mineral that may be present in some supplements and is also used in large amounts to treat mood disorders such as bipolar disorder (manic depression). One study reviewed four cases in which individuals stabilised on lithium medication developed side effects such as delirium, seizures, and abnormal electrical activity in the brain when thioridazine was added.⁵ Further research is needed to determine whether similar side effects might occur in individuals taking thioridazine and supplemental lithium.

Vitamin C
Taking phenothiazine drugs can stop menstruation in some women. A 45-year-old woman taking thioridazine started menstruating once she began supplementing with 6 grams of vitamin C daily.⁶ Controlled studies are needed to determine whether women taking thioridazine, who are experiencing menstrual changes, might benefit from supplemental vitamin C. Vitamin C might also enhance the effectiveness of neuroleptic drugs, such as thioridazine, in the treatment of schizophrenia. One uncontrolled study showed that 10 of 13 individuals experienced a reduction in disorganized thoughts, hallucinations, and suspicious thoughts when 8 grams of vitamin C was added to their daily drug therapy.⁷ Controlled studies are needed to determine whether people taking thioridazine for schizophrenia might benefit from vitamin C supplementation.

Interactions with Herbs

Bacopa
An animal study found that the effects of chlorpromazine, a drug similar to (perphenazine, prochlorperazine, thioridazine), were enhanced when a bacopa extract was given along with it.⁸ Until more is known, people taking medications from this family of drugs (called phenothiazines) should not take bacopa.

Interactions with Foods and Other Compounds

Alcohol
Drinking alcoholic drinks while taking thioridazine may enhance the actions of alcohol, such as drowsiness, dizziness, and lack of concentration,⁹ and should be avoided. Two individuals withdrawing from chronic alcohol consumption experienced serious changes in heart function when they were given thioridazine;¹⁰ therefore, the drug should be used with caution in people who are attempting to quit drinking.

References

1. Curtis JL. Effects of medication on plasma vitamin A concentrations. Clin Chem 1976;22:695.

2. Sydney MA. Ventricular arrhythmias associated with use of thioridazine hydrochloride in alcohol withdrawal. Br Med J 1973;4:467.

3. Lehmann HE, Ban TA, Saxena BM. Nicotinic acid, thioridazine, fluoxymesterone and their combinations in hospitalized geriatric patients. Can Psychiatr Assoc J 1972;17:315–20.

4. Kishi T, Makino K, Okamoto T, et al. In Yamamura Y, Folkers K, Ito Y, eds. Biochemical and Clinical Aspects of Coenzyme Q, Volume 2. Amsterdam: Elsevier/North Holland Biomedical Press, 1980, 139–57.

5. Spring GK. Neurotoxicity with combined use of lithium and thioridazine. J Clin Psychiatry 1979;40:135–8.

6. Kanofsky JD, Kay SR, Lindenmayer JP, Seifter E. Ascorbic acid action in neuroleptic-associated amenorrhea. J Clin Psychopharmacol 1989;9:388–9 [letter].

7. Beauclair L, Vinogradov S, Riney SJ, et al. An adjunctive role for ascorbic acid in the treatment of schizophrenia? J Clin Psychopharmacol 1987;7:282–3.

8. Ganguly DK, Malhotra CL. Some behavioral effects of an active fraction from Herpestis monniera Linn. (Brahmi). Indian J Med Res 1967;55:473–82.

9. Sifton DW, ed. Physicians Desk Reference. Montvale, NJ: Medical Economics Company, Inc., 2000, 1973–4.

10. Sydney MA. Ventricular arrhythmias associated with use of thioridazine hydrochloride in alcohol withdrawal. Br Med J 1973;4:467.

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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or chemist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires August 2007.