Pharmacology Guide
Anti-Psychotics
Date Created
Date Modified
Risperidone (Risperdal) |
Haloperidol (Haldol) |
Thioridazine (Mellaril) |
Chlorpromazine (Thorazine) |
Fluphenazine (Prolixin)
Risperidone
| Risperdal |
Mechanism of Action
|
Mechanism of action is believed to be due to antagonism of dopamine (D2) and serotonin (5-HT2) receptors. |
Therapeutic Use
|
Treatment of psychotic disorders. |
Absorption
|
Well absorbed after oral administration. Peak plasma levels are reached in 1 hour. |
Metabolism
|
Metabolized in the liver by cytochrome P450. |
Half-life
|
3 Hours, but may be as long as 20 hours in a segment of the population that are slow metabolizers . |
Average Daily Dose (adult)
|
4-6 mg |
Adverse Effects
|
Somnolence (sleepiness), headache, dizziness, tremor, dystonia, Parkinsonism, and weight gain. |
Drug Interaction
|
Caution should be used when taken in combination with other centrally acting drugs and alcohol. Because of its potential for inducing hypotension, Risperdal may enhance the hypotensive effects of other therapeutic agents with this potential. Potential interaction with other drugs metabolized by P-450 enzymes. |
Contraindication
|
Contraindicated during lactation. Use with caution in individuals with cardiovascular and cerebrovascular disease. |
Haloperidol
|
Haldol |
Mechanism of Action
|
Believed to be due to blockade of dopamine (D2) receptors in the limbic system. |
Therapeutic Use
|
Treatment of psychotic disorders including acute mania, drug-induced sychoses and schizophrenia. Also, for aggressive and agitated clients. Control of tics and vocal utterances of Tourette s Disorder. |
Absorption
|
Peak effect 3-5 hours. |
Metabolism
|
Oxidized by P-450 enzymes. |
Half-life
|
18-25 hours. |
Average Daily Dose (adult)
|
1-6 mg |
Adverse Effects
|
Extrapyramidal symptoms (involuntary movement). hyperprolactinemia, weight gain, risk of tardive dyskinesia, dry mouth, hypotension. |
Drug Interaction
|
May be capable of potentiating CNS depressants such as anesthetics, opiates and alcohol. Caution should be exercised in patients receiving lithium. |
Contraindication
|
Severe toxic CNS depression or comatose states from any cause and in individuals who are hypersensitive to this drug or have Parkinson s disease. Lactation. |
Thioridazine
|
Mellaril |
Mechanism of Action
|
Believed to be due to blockade of dopamine (D2) receptors in limbic system. |
Therapeutic Use
|
Treatment of schizophrenia, depression of anxiety, and sleep disturbances. |
Absorption
|
Erratic absorption after oral administration. Time for peak effect: 1-4 hours. |
Metabolism
|
Metabolized in liver by P-450 enzymes. |
Half-life
|
15-20 hours. |
Average Daily Dose (adult)
|
150-600 mg |
Adverse Effects
|
Drowsiness, dry mouth, blurred vision, urinary retention, orthostatic hypotension. |
Drug Interaction
|
Additive sedative effects with other CNS depressants; potential interaction with other drugs metabolized by P-450 enzymes. |
Contraindication
|
Should not be given to patients with Parkinson s disease or cardiovascular disease. |
Chlorpromazine
|
Thorazine |
Mechanism of Action
|
Blocks dopamine (D2) receptors in limbic system. |
Therapeutic Use
|
Treatment of psychosis, schizophrenia and acute mania. Can be used to control nausea & vomiting. |
Absorption
|
Erratically absorbed. Peak effect in 2-3 Hours. |
Metabolism
|
Extensive oxidation by P-450 enzymes. |
Half-life
|
30 Hours. |
Average Daily Dose (adult)
|
300-1000 mg |
Adverse Effects
|
Drowsiness, orthostatic hypotension, dry mouth, blurred vision, xtrapyramidal motor effects (e.g. Parkinsonism, acute dystonia). Danger of tardive dyskinesia. |
Drug Interaction
|
Potential interaction with other drugs metabolized by P-450 system. Additive effect with other CNS depressants. |
Contraindication
|
Do not use in patients with known hypersensitivity to phenothiazines. Do not use in comatose states or in the presence of large amounts of CNS depressants, (Alcohol, barbiturates, narcotics etc). |
Fluphenazine
|
Prolixin |
Mechanism of Action
|
Blocks dopamine (D2) receptors in the limbic system. |
Therapeutic Use
|
Treatment of psychotic disorders. |
Absorption
|
Well absorbed. Peak plasma level: 1-4 hours. |
Metabolism
|
Oxidized by the P-450 system. |
Half-life
|
20 hours after oral administration. |
Average Daily Dose (adult)
|
5-10 mg/day |
Adverse Effects
|
High incidence of extrapyramidal symptoms (involuntary movement). Risk of tardive dyskinesia. |
Drug Interaction
|
Additive with other CNS depressants such as benzodiazepines and alcohol. May interact with other drugs that are metabolized by the P-450 enzymes. |
Contraindication
|
Hypersensitivity to phenothiazines. Do not use in comatose states or in the presence of large amounts of CNS depressants. |
These brief pharmaceutical summaries do not include all information important for patient use and should not be used as a substitute for professional medical advice. Consult the prescribing doctor and read package inserts before using these or any other medications or supplements.
CDER
U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
Public Health Service
National Institutes of Health
Baldessarini, R. J. In Goodman and Gilman s The Pharmacological Basis of Therapeutics 9th Edition. Elovic, E. (1996). Atypical antipsychotics: risperidone and clozapine. Journal of Head Trauma Rehabilitation . 11(3), 89-92.
Emory, L.E., Cole, C.M., & Meyer, III, W.J. (1995). Use of Depo-Provera to control sexual aggression in persons with traumatic brain injury. Journal of Head Trauma Rehabilitation . 10(3), 47-58Jean-blanc, W. & Davis, Y. (1995). Risperidone for treating dementia-associated aggression. American Journal of Psychiatry. 152(8), 1239.
Physicians Desk Reference, 1998.
Rose, M.J. (1988). The place of drugs in the management of behavior disorders after traumatic brain injury. Journal of Head Trauma Rehabilitation . 3(3), 7-13. Silver, J.M. & Yudofsky, S.C. (1994). Psychopharmacological approaches to the patient with affective and psychotic features. Journal of Head Trauma Rehabilitation . 9(3), 61.
Wilkinson, R., Meythaler, J. & Guin-Renfroe, S. (1999). Neuroleptic malignant syndrome by haloperidol following traumatic brain injury. Brain Injury . 13(12), 1025.
