Fluphenazine
Definition
Fluphenazine is a phenothiazine antipsychotic sold under the brand names Permitil and Prolixin in the United States. It is also available under its generic name.
Description
Fluphenazine is one of many drugs in the group called the phenothiazines. Phenothiazines work by inhibiting the actions of the brain chemicals, dopamine and norepinephrine, which are overproduced in individuals with psychosis .
Fluphenazine is available in 1-mg, 2.5-mg, 5-mg, and 10-mg tablets, a liquid concentrate containing 5 mg per 1 mL, a rapid-onset injectable form containing 2.5 mg per 1 mL, and a long-acting injectable form containing 25 mg per 1 mL.
Recommended dosage
In children over age 16 and in adults, fluphenazine is usually given in oral dosages ranging from 0.5–10 mg daily. The total dosage is usually divided and taken two to four times throughout the day. The dosage is typically reduced at a gradual pace over time to a range between 1 mg and 5 mg. Older adults usually receive lower doses that begin in the range of 1 mg–2.5 mg per day. In children under age 16, the usual range is 0.25–3.5 mg per day divided into several doses. Maximum dosage is normally 10 mg per day for this age group.
This drug is also available by injection. In adults, injections into the muscle range from 1.25–10 mg per day divided into several doses. A long-acting injectable form can also be administered to patients who have been stabilized on the drug. The dose for the long-acting preparation ranges from 12.5–25 mg given every one to four weeks in adults. The dosage for children is lower in all cases.
Precautions
People with a history of depression, lung problems, heart disease, glaucoma, seizures , and kidney disease should take fluphenazine only after careful evaluation by their physician. In addition, those undergoing alcohol withdrawal and those who have received electroconvulsive therapy should take this drug with great caution and close physician supervision after discussing the risks and benefits with their doctor. Those over age 60 and children under age 12 should take fluphenazine only after a thorough assessment from their physician. Pregnant women should use fluphenazine with great caution.
Fluphenazine may cause drowsiness. People who take this drug should not drive, operate heavy machinery, or perform other hazardous tasks requiring mental alertness until they see how the drug affects them. People taking fluphenazine should avoid significant exposure to sunlight, as the drug may cause people to sunburn more easily. This drug can sometimes change the color of urine to a pinkish or reddish-brown color. Fluphenazine use can make people more susceptible to heat and increase the risk of heatstroke. People taking fluphenazine should get up slowly after being in a reclining position because of potential dizziness.
Side effects
Relatively common side effects that accompany fluphenazine include drowsiness, dizziness, rash, dry mouth, insomnia , fatigue , muscular weakness, anorexia, blurred vision, some loss of muscular control, and amenorrhea (lack of menstruation) in women.
Dystonia (difficulty walking or moving) may occur with fluphenazine use. This condition may subside in 24 to 48 hours even when the person continues taking the drug and usually disappears when fluphenazine is discontinued.
Fluphenazine use may lead to the development of symptoms that resemble Parkinson's disease. These symptoms may include a tight or mask-like expression on the face, drooling, tremors, pill-rolling motions in the hands, cogwheel rigidity (abnormal rigidity in muscles characterized by jerky movements when the muscle is passively stretched), and a shuffling gait. Taking anti-Parkinson drugs benztropine mesylate or trihexyphenidyl hydrochloride along with the fluphenazine usually controls these symptoms.
Fluphenazine has the potential to produce a serious side effect called tardive dyskinesia . This syndrome consists of involuntary, uncoordinated movements that may appear late in therapy and may not disappear even after the drug is stopped. Tardive dyskinesia involves involuntary movements of the tongue, jaw, mouth or face or other groups of skeletal muscles. The incidence of tardive dyskinesia increases with increasing age and with increasing dosage of fluphenazine. Women are at greater risk than men for developing tardive dyskinesia. There is no known effective treatment for tardive dyskinesia, although gradual (but rarely complete) improvement may occur over a long period.
An occasionally reported side effect of fluphenazine is neuroleptic malignant syndrome. This is a complicated and potentially fatal condition characterized by muscle rigidity, high fever, alterations in mental status, and cardiac symptoms such as irregular pulse or blood pressure, sweating, tachycardia (fast heartbeat), and arrhythmias (irregular heartbeat). People who think they may be experiencing any side effects from this or any other medication should talk to their physician promptly.
Interactions
Barbiturates lower the level of fluphenazine in the blood. The blood pressure drugs known as beta-blockers tend to decrease the level of fluphenazine in the blood. Bromocriptine, a drug used for Parkinson's disease, also lowers the level of fluphenazine in the blood. Conversely, antimalarial drugs can increase the level of fluphenazine in the blood.
The combination of fluphenazine with the drugs known as cyclic antidepressants lowers the concentrations of both drugs in the blood. Fluphenazine inhibits the blood pressure-lowering effects of the drug called guanadrel. Levodopa, a drug given to patients with Parkinson disease, is less effective when combined with fluphenazine. The combination of fluphenazine with meperidine can cause very low blood pressure and significant depression of the central nervous system. The use of the muscle relaxant, orphenadrine, can lower the effective levels of fluphenazine in the blood.
Resources
BOOKS
Consumer Reports Staff. Consumer Reports Complete Drug Reference. 2002 ed. Denver: Micromedex Thomson Healthcare, 2001.
Ellsworth, Allan J. and others. Mosby's Medical Drug Reference. 2001-2002. St. Louis: Mosby, 2001.
Hardman, Joel G., Lee E. Limbird,ed. Goodman & Gilman's The Pharmacological Basis of Therapeutics . 10th ed. New York: McGraw-Hill, 2001.
Mosby's GenRx Staff. Mosby's GenRx. 9th ed. St. Louis: Mosby, 1999.
Venes, Donald, and others. Taber's Cyclopedic Medical Dictionary. 19th ed. Philadelphia: F. A. Davis, 2001.
Mark Mitchell,M.D.
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