VA Class:CN701

AHFS Class:

• Phenothiazines 28:16.08.24

Generic Name(s):

• chlorproMAZINE Hydrochloride

• chlorproMAZINE

Chemical Name:

• 2-Chloro-10-[3-(dimethylamino)propyl]-phenothiazine monohydrochloride

Molecular Formula:

• C₁₇H₁₉CIN₂S HCl

Chlorpromazine hydrochloride is a phenothiazine antipsychotic agent.

Psychotic Disorders

Chlorpromazine hydrochloride is used for the symptomatic management of psychotic disorders. Drug therapy is integral to the management of acute psychotic episodes in patients with schizophrenia and generally is required for long-term stabilization to improve symptoms between episodes and to minimize the risk of recurrent acute episodes. Antipsychotic agents are the principal class of drugs used for the management of all phases of schizophrenia and generally are effective in all subtypes of the disorder and subgroups of patients. Patient response and tolerance to antipsychotic agents are variable, and patients who do not respond to or tolerate one drug may be successfully treated with an agent from a different class or with a different adverse effect profile. For additional information on the symptomatic management of schizophrenia, see Uses: Psychotic Disorders, in the Phenothiazines General Statement 28:16.08.24.

Other Uses

Chlorpromazine is used for the prevention and treatment of nausea and vomiting; for relief of restlessness and apprehension before surgery; for acute intermittent porphyria; as an adjunct in the treatment of tetanus; for the symptomatic management of the manic phase of bipolar disorder; and for relief of intractable hiccups.

Chlorpromazine is also used for the treatment of severe behavioral problems in children marked by combativeness and/or explosive hyperexcitable behavior (out of proportion to immediate provocations), and for the short-term treatment of hyperactive children who exhibit excessive motor activity with accompanying conduct disorders that are manifested as impulsivity, difficulty sustaining attention, aggression, mood lability, and/or poor frustration tolerance. However, the possible risks of tardive dyskinesia, withdrawal dyskinesia, and other extrapyramidal reactions associated with the drug should be considered. Some clinicians recommend routine administration of the Abnormal Involuntary Movement Scale (AIMS) to all children receiving antipsychotic agents for this indication.

Chlorpromazine may be effective in controlling anxiety, tension, and agitation which occur in neuroses. Further studies are needed to establish the efficacy of the drug for this use.

Administration

Chlorpromazine hydrochloride may be administered orally, by deep IM or direct IV injection, or by IV infusion. Direct IV injection is intended for use only during surgery to control nausea and vomiting and in the adjunctive treatment of tetanus. IV infusion is only intended for use in the adjunctive treatment of intractable hiccups in adults. Subcutaneous administration of the drug is not recommended because of local irritation. Parenteral therapy should be reserved for recumbent patients; however, if cautions are taken to avoid orthostatic hypotension (i.e., patient remains recumbent for at least 30 minutes after injection), acutely agitated ambulatory patients may receive the drug IM.

For IM administration, injection should be made slowly, deep into a large muscle mass such as the upper outer quadrant of the gluteus maximus; if irritation at the IM injection site is a problem, the drug can be diluted with 0.9% sodium chloride injection or 2% procaine hydrochloride. For direct IV injection, chlorpromazine hydrochloride injection should be diluted with 0.9% sodium chloride injection to a concentration not exceeding 1 mg/mL and administered at a rate of 1 mg/minute in adults and 0.5 mg/minute in children. IV administration of undiluted chlorpromazine hydrochloride injection should be avoided. For IV infusion, chlorpromazine hydrochloride injection should be added to 500-1000 mL of 0.9% sodium chloride injection and administered slowly.

Dosage

Dosage of chlorpromazine hydrochloride is expressed in terms of the hydrochloride salt.

The manufacturers state that the 100- and 200-mg tablets of chlorpromazine hydrochloride are intended for use in patients with severe neuropsychiatric conditions.

Dosage must be carefully adjusted according to individual requirements and response, using the lowest possible effective dosage. Dosage should be increased more gradually in debilitated, emaciated, or geriatric patients. Since geriatric patients may be more susceptible to hypotension and neuromuscular reactions, these patients should be observed closely; in general, dosages in the lower end of the range are sufficient for most geriatric patients. Because of the risk of adverse reactions associated with cumulative effects of phenothiazines, patients with a history of long-term therapy with chlorpromazine and/or other antipsychotic agents should be evaluated periodically to determine whether maintenance dosage should be decreased or drug therapy discontinued. Chlorpromazine should generally not be used in children younger than 6 months of age unless the condition to be treated is potentially life-threatening; dosage in this age group has not been established.

Psychotic Disorders and Excessive Anxiety, Tension, and Agitation

Adult Dosage

For the symptomatic management of psychotic disorders in non-hospitalized patients with relatively mild symptomatology and for the management of excessive anxiety, tension, and agitation, the usual initial adult oral dosage of chlorpromazine hydrochloride is 30-75 mg daily given in 2-4 divided doses. For non-hospitalized patients with moderate to severe symptomatology, the usual initial adult oral dosage is 25 mg 3 times daily. After 1 or 2 days, dosage may be gradually increased twice weekly by 20-50 mg until symptoms are controlled. Although symptomatic relief may be seen in many patients during the first week of therapy, optimum therapeutic response may not occur for weeks or even months in some severely disturbed or symptomatic patients. Once an optimum dosage is achieved, this dosage should be continued for 2 weeks and then gradually reduced to the lowest possible effective dosage. In adult patients with excessive anxiety, tension, and agitation, the usual oral dosage during prolonged maintenance therapy is 200 mg daily; however, oral dosages up to 800 mg daily may be required in some patients (e.g., discharged psychiatric patients).

For prompt control of severe symptoms in non-hospitalized patients or in patients with anxiety, tension, and agitation, an IM chlorpromazine hydrochloride dose of 25 mg may be given initially; this dose may be repeated in 1 hour, if necessary. After the patient's symptoms are controlled, oral therapy should replace parenteral therapy at a dosage of 25-50 mg 3 times daily.

For the symptomatic management of psychotic disorders in hospitalized patients who are acutely agitated, manic, or disturbed, the usual initial adult IM dose of chlorpromazine hydrochloride is 25 mg. Additional IM doses of 25-50 mg may be given in 1 hour, if necessary. Subsequent IM dosage should be gradually increased over several days to a maximum of 400 mg every 4-6 hours until symptoms are controlled. Usually, patients become quiet and cooperative within 24-48 hours after initiation of therapy; oral therapy should replace parenteral therapy and dosage should be increased until the patient is calm. Oral dosages of 500 mg daily are generally sufficient in most patients. Although oral dosages greater than 2 g daily may be required in some patients, there is usually little therapeutic gain achieved by exceeding dosages of 1 g daily for extended periods. For hospitalized patients who are less acutely agitated, the usual initial adult oral dosage of chlorpromazine hydrochloride is 25 mg 3 times daily. Subsequent dosage should be gradually increased until optimum therapeutic response is obtained, but should usually not exceed 400 mg daily.

Pediatric Dosage

The usual initial oral dosage of chlorpromazine hydrochloride for the management of psychotic disorders and behavioral problems in children 6 months of age or older is 0.55 mg/kg every 4-6 hours as necessary.

The usual initial IM dosage of chlorpromazine hydrochloride for the management of psychotic disorders and behavioral problems in children 6 months of age or older is 0.55 mg/kg every 6-8 hours as necessary. Subsequent dosage may be gradually increased as necessary.

Higher dosages (50-100 mg daily) may be necessary in children with severe behavior disorders or psychotic conditions; older children may require 200 mg daily. There is little evidence that improvement in behavior in severely disturbed mentally retarded children is further enhanced at oral dosages greater than 500 mg daily. Maximum IM dosage of chlorpromazine hydrochloride in children younger than 5 years of age and in those weighing less than 22.7 kg is 40 mg daily; maximum IM dosage in children 5-12 years of age and weighing 22.7-45.5 kg should not exceed 75 mg daily, except in unmanageable patients.

Nausea and Vomiting

Adult Dosage

For the prevention and treatment of nausea and vomiting in patients who can tolerate oral administration of the drug, the usual initial adult oral dosage of chlorpromazine hydrochloride is 10-25 mg every 4-6 hours as necessary; dosage may be increased if necessary. The usual adult rectal dosage for the prevention and control of nausea and vomiting is 100 mg every 6-8 hours as necessary; in some patients, 50 mg every 6-8 hours will be adequate. The usual initial adult IM dose of chlorpromazine hydrochloride for the control of nausea and vomiting is 25 mg. If hypotension does not occur, additional IM doses of 25-50 mg may be administered as necessary every 3-4 hours until symptoms subside; oral therapy should then replace parenteral therapy if necessary.

Pediatric Dosage

For the prevention and treatment of nausea and vomiting in children 6 months of age or older, the usual oral dosage of chlorpromazine hydrochloride is 0.55 mg/kg every 4-6 hours.

The usual initial IM dosage of chlorpromazine hydrochloride for the control of nausea and vomiting in these children is 0.55 mg/kg every 6-8 hours as necessary. Subsequent dosage should be carefully adjusted according to the severity of symptoms and the patient's response. Maximum IM dosage of chlorpromazine hydrochloride in children younger than 5 years of age and in those weighing less than 22.7 kg is 40 mg daily; maximum IM dosage in children 5-12 years of age and weighing 22.7-45.5 kg should not exceed 75 mg daily, except in severe cases.

Intermittent Porphyria

For acute intermittent porphyria, the usual adult oral dosage of chlorpromazine hydrochloride is 25-50 mg 3 or 4 times daily. The usual adult IM dosage of chlorpromazine hydrochloride for acute intermittent porphyria is 25 mg 3 or 4 times daily. Oral therapy should replace parenteral therapy as soon as the patient can tolerate oral administration of the drug. Therapy can usually be discontinued after several weeks; however, maintenance therapy may be required in some patients.

Intractable Hiccups

For relief of intractable hiccups, the usual adult oral dosage of chlorpromazine hydrochloride is 25-50 mg 3 or 4 times daily. If symptoms persist for 2-3 days, 25-50 mg may be given IM. If hiccups continue, 25-50 mg of the drug may be administered by slow IV infusion (see Dosage and Administration: Administration) with the patient in a supine position. Blood pressure should be closely monitored during IV administration of chlorpromazine.

Tetanus

For adjunctive treatment of tetanus, the usual initial adult IM dosage of chlorpromazine hydrochloride is 25-50 mg 3 or 4 times daily, usually in conjunction with barbiturates. The usual adult direct IV dose of the drug is 25-50 mg. (See Dosage and Administration: Administration.) The usual IM or direct IV dosage of chlorpromazine hydrochloride for adjunctive treatment of tetanus in children 6 months of age or older is 0.55 mg/kg every 6-8 hours. Maximum parenteral dosage of chlorpromazine hydrochloride in children weighing less than 22.7 kg is 40 mg daily; maximum parenteral dosage in children weighing 22.7-45.5 kg should not exceed 75 mg daily, except in severe cases.

Surgery

For relief of restlessness and apprehension before surgery, the usual adult oral dose of chlorpromazine hydrochloride is 25-50 mg given 2-3 hours before surgery. The usual adult IM dose is 12.5-25 mg given 1-2 hours before surgery. For relief of restlessness and apprehension before surgery in children 6 months of age or older, the usual oral or IM dose of chlorpromazine hydrochloride is 0.55 mg/kg administered 2-3 or 1-2 hours before surgery, respectively.

To control acute nausea and vomiting during surgery, the usual adult IM dose of chlorpromazine hydrochloride is 12.5 mg; this dose may be repeated in 30 minutes, if necessary and if hypotension does not occur. Alternatively during surgery in adults, fractional 2-mg doses may be given IV at 2-minute intervals up to a maximum total dose of 25 mg. To control acute nausea and vomiting during surgery in children 6 months of age or older, the usual IM dose of chlorpromazine hydrochloride is 0.275 mg/kg; this dose may be repeated in 30 minutes, if necessary and if hypotension does not occur. Alternatively during surgery in these children, fractional 1-mg doses may be given IV at 2-minute intervals up to a total dose of 0.275 mg/kg; if after 30 minutes it is necessary to readminister the drug and if hypotension does not occur, the fractional IV dosage regimen may be repeated.

Following surgery, the usual adult oral dosage of chlorpromazine hydrochloride is 10-25 mg every 4-6 hours as necessary. The usual adult IM dose of chlorpromazine hydrochloride following surgery is 12.5-25 mg; this dose may be repeated in 1 hour, if necessary and if hypotension does not occur. Following surgery in children 6 months of age or older, the usual initial oral or IM dose of chlorpromazine hydrochloride is 0.55 mg/kg. The initial oral dose may be repeated every 4-6 hours as needed; the initial IM dose may be repeated in 1 hour, if necessary and if hypotension does not occur.

Chlorpromazine hydrochloride shares the toxic potentials of other phenothiazines, and the usual precautions of phenothiazine therapy should be observed. (See Cautions in the Phenothiazines General Statement 28:16.08.24.)

Geriatric patients with dementia-related psychosis treated with either conventional (first-generation) or atypical (second-generation) antipsychotic agents are at an increased risk of mortality.100,101,102,103,104,105,106 For additional information on the use of antipsychotic agents for dementia-associated psychosis and other behavioral disturbances, see Geriatric Considerations under Psychotic Disorders: Schizophrenia and Other Psychotic Disorders, in Uses and see Cautions: Geriatric Precautions, in the Phenothiazines General Statement 28:16.08.24.

Care should be taken to avoid skin contact with chlorpromazine hydrochloride injection, since contact dermatitis has occurred rarely.

Commercially available chlorpromazine hydrochloride injection contains sulfites that may cause allergic-type reactions, including anaphylaxis and life-threatening or less severe asthmatic episodes, in certain susceptible individuals. The overall prevalence of sulfite sensitivity in the general population is unknown but probably low; such sensitivity appears to occur more frequently in asthmatic than in nonasthmatic individuals.

Safety and efficacy of chlorpromazine in children younger than 6 months of age have not been established; the manufacturers recommend that the drug should generally not be used in these children unless the condition to be treated is potentially life-threatening.105,106 Chlorpromazine should not be used in conditions for which a pediatric dosage has not been established.105,106

Pharmacology

The principal pharmacologic effects of chlorpromazine hydrochloride are similar to those of other propylamino derivatives of phenothiazine. Chlorpromazine has strong anticholinergic and sedative effects and moderate extrapyramidal effects. Chlorpromazine has strong antiemetic and adrenergic blocking activity and weak ganglionic blocking, antihistaminic, and antiserotonergic activity.

Pharmacokinetics

Absorption

Chlorpromazine hydrochloride is rapidly absorbed from the GI tract and from parenteral sites of injection; however, following oral administration, the drug undergoes considerable metabolism during absorption (in the GI mucosa) and first pass through the liver. Although not clearly established in humans, chlorpromazine and its metabolites undergo enterohepatic circulation in animals. (See Pharmacokinetics: Elimination.)

Considerable interindividual variations in peak plasma concentrations have been reported with the same oral dose of chlorpromazine. The variability is thought to result from wide interindividual variation in bioavailability, apparently because of genetic differences in the rate of first-pass metabolism. As a result of first-pass metabolism, less chlorpromazine reaches systemic circulation as unchanged drug, and peak plasma chlorpromazine concentrations are much lower following oral administration than following IM administration.

Following oral administration of chlorpromazine hydrochloride in a tablet formulation, the onset of pharmacologic action occurs within 30-60 minutes; the duration of action is 4-6 hours.

The therapeutic range for plasma chlorpromazine concentrations and the relationship of plasma concentration to clinical response and toxicity have not been clearly established.

Distribution

Chlorpromazine is widely distributed into most body tissues and fluids. Chlorpromazine crosses the blood-brain barrier, and concentrations of the drug in the brain are higher than those in plasma.

Chlorpromazine is 92-97% bound to plasma proteins, principally albumin, at plasma chlorpromazine concentrations of 0.01-1 mcg/mL.

Chlorpromazine and its metabolites cross the placenta and are distributed into milk.

Elimination

Although the exact metabolic fate of chlorpromazine is not clearly established, the drug is extensively metabolized, principally in the liver and kidneys. About 10-12 metabolites which occur in humans in appreciable quantities have been identified. In addition to hydroxylation at positions 3 and 7 of the phenothiazine nucleus, the N -dimethylaminopropyl side chain of chlorpromazine undergoes demethylation and is also metabolized to an N -oxide. Two principal groups of metabolites have been found in urine. The unconjugated fraction, which represents approximately 20% of chlorpromazine and its metabolites excreted in urine, consists of unchanged drug, demonomethylchlorpromazine, dedimethylchlorpromazine, their sulfoxide metabolites, and chlorpromazine- N -oxide. The conjugated fraction, which represents approximately 80% of chlorpromazine and its metabolites excreted in urine, consists principally of O -glucuronides, with small amounts of ethereal sulfates of the mono- and dihydroxy-derivatives of chlorpromazine and their sulfoxide metabolites. The major metabolites found in urine are the monoglucuronide of N -dedimethylchlorpromazine and 7-hydroxychlorpromazine.

Following a single oral chlorpromazine dose of 120 mg/m² to 4 healthy men, less than 1% of the dose was excreted in urine as unchanged drug within 72 hours, with most urinary excretion of unchanged drug occurring within 6 hours. Following continuous oral administration of chlorpromazine to a limited number of psychiatric patients in a dosage ranging from 0.1-1.4 g daily, an average of 37% of the dose was excreted in urine, principally as metabolites. In blacks, a relatively high percentage of chlorpromazine is excreted in urine as unconjugated 7-hydroxychlorpromazine; however, in whites, this may be an indication of existing or developing hyperpigmentation of the skin.

Chemistry and Stability

Chemistry

Chlorpromazine hydrochloride is a phenothiazine antipsychotic agent. The drug is a propylamino derivative of phenothiazine and is structurally similar to promazine, but differs from promazine in the substitution of a chlorine atom for hydrogen at the 2 position of the phenothiazine nucleus. Chlorpromazine is commercially available as the hydrochloride salt. Each 111 mg of chlorpromazine hydrochloride is approximately equivalent to 100 mg of chlorpromazine base.

Chlorpromazine occurs as a white, crystalline solid that has an amine odor and is practically insoluble in water and freely soluble in alcohol. Chlorpromazine hydrochloride occurs as a white or slightly creamy white, odorless, very bitter tasting, crystalline powder and has approximate solubilities of 1 g/mL in water and 667 mg/mL in alcohol at 25°C.

Chlorpromazine hydrochloride injection is a sterile solution of the drug in water for injection. The commercially available injection has a pH of 3-5 and may contain benzyl alcohol as a preservative, a sulfite(s), and other excipients.

Stability

Chlorpromazine and its hydrochloride salt darken on prolonged exposure to light. Commercially available preparations of chlorpromazine hydrochloride should therefore be protected from light. Chlorpromazine hydrochloride tablets should be stored in well-closed, light-resistant containers at 20-25°C (excursions permitted to 15-30°C) and protected from moisture.105 Chlorpromazine hydrochloride injection should be stored at 20-25°C (excursions permitted to 15-30°C); freezing of the injection should be avoided.106 Slight yellowish discoloration of the injection will not affect potency or efficacy, but it should not be used if markedly discolored or if a precipitate is present. At the time of manufacture, air in the containers of the commercially available chlorpromazine hydrochloride injection is replaced with nitrogen to avoid oxidation. Oxidation of chlorpromazine hydrochloride occurs readily in alkaline media.

Chlorpromazine hydrochloride injection is physically and/or chemically incompatible with some drugs, but the compatibility depends on several factors (e.g., concentrations of the drugs, specific diluents used, resulting pH, temperature). Specialized references should be consulted for specific compatibility information.

Additional Information

For further information on chemistry and stability, pharmacology, pharmacokinetics, uses, cautions, acute toxicity, drug interactions, laboratory test interferences, and dosage and administration of chlorpromazine hydrochloride, see the Phenothiazines General Statement 28:16.08.24.

Only references cited for selected revisions after 1984 are available electronically.

100. Sandoz, Inc. ChlorproMAZINE hydrochloride tablets prescribing information. Princeton, NJ; 2008 Sep.

101. Food and Drug Administration. FDA Alert: Information for healthcare professionals: antipsychotics. Rockville, MD; 2008 Jun 16. From the FDA website. [Web]

102. Food and Drug Administration. FDA News: FDA requests boxed warnings on older class of antipsychotic drugs. Rockville, MD; 2008 Jun 16. From the FDA website. [Web]

103. Schneeweiss S, Setoguchi S, Brookhart A et al. Risk of death associated with the use of conventional versus atypical antipsychotic drugs among elderly patients. CMAJ . 2007; 176:627-32. [PubMedCentral][PubMed 17325327]

104. Gill SS, Bronskill SE, Normand SL et al. Antipsychotic drug use and mortality in older adults with dementia. Ann Intern Med . 2007; 146:775-86. [PubMed 17548409]

105. Upsher-Smith Laboratories, Inc. Chlorpromazine hydrochloride tablets prescribing information. Minneapolis, MN; 2011 Jun.

106. Baxter Healthcare Corporation. Chlorpromazine hydrochloride injection, solution prescribing information. Deerfield, IL; 2010 Sep.