Chlorpromazine may cause somnolence, postural hypotension, motor and sensory instability, which may lead to falls and, consequently, fractures or other injuries. For patients with diseases, conditions, or medications that could exacerbate these effects, complete fall risk assessments when initiating antipsychotic treatment and recurrently for patients on long-term antipsychotic therapy.
Usage in Pregnancy: Safety for the use of chlorpromazine during pregnancy has not been established. Therefore, it is not recommended that the drug be given to pregnant patients except when, in the judgment of the physician, it is essential. The potential benefits should clearly outweigh possible hazards. There are reported instances of prolonged jaundice, extrapyramidal signs, hyperreflexia or hyporeflexia in newborn infants whose mothers received phenothiazines.
Reproductive studies in rodents have demonstrated potential for embryotoxicity, increased neonatal mortality and nursing transfer of the drug. Tests in the offspring of the drug–treated rodents demonstrate decreased performance. The possibility of permanent neurological damage cannot be excluded.
Non-teratogenic Effects: Neonates exposed to antipsychotic drugs, during the third trimester of pregnancy are at risk for extrapyramidal and/or withdrawal symptoms following delivery. There have been reports of agitation, hypertonia, hypotonia, tremor, somnolence, respiratory distress and feeding disorder in these neonates. These complications have varied in severity; while in some cases symptoms have been self-limited, in other cases neonates have required intensive care unit support and prolonged hospitalization.
Chlorpromazine Hydrochloride should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Nursing Mothers: There is evidence that chlorpromazine is excreted in the breast milk of nursing mothers. Because of the potential for serious adverse reactions in nursing infants from chlorpromazine, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
In clinical trial and postmarketing experience, events of leukopenia/neutropenia and agranulocytosis have been reported temporally related to antipsychotic agents.
Possible risk factors for leukopenia/neutropenia include preexisting low white blood cell count (WBC) and history of drug induced leukopenia/neutropenia. Patients with a preexisting low WBC or a history of drug induced leukopenia/neutropenia should have their complete blood count (CBC) monitored frequently during the first few months of therapy and should discontinue Chlorpromazine Hydrochloride Tablets, USP at the first sign of a decline in WBC in the absence of other causative factors.
Patients with neutropenia should be carefully monitored for fever or other symptoms or signs of infection and treated promptly if such symptoms or signs occur. Patients with severe neutropenia (absolute neutrophil count <1000/mm 3) should discontinue Chlorpromazine Hydrochloride Tablets, USP and have their WBC followed until recovery.
Given the likelihood that some patients exposed chronically to antipsychotics will develop tardive dyskinesia, it is advised that all patients in whom chronic use is contemplated be given, if possible, full information about this risk. The decision to inform patients and/or their guardians must obviously take into account the clinical circumstances and the competency of the patient to understand the information provided.
Chlorpromazine should be administered cautiously to persons with cardiovascular, liver or renal disease. There is evidence that patients with a history of hepatic encephalopathy due to cirrhosis have increased sensitivity to the CNS effects of chlorpromazine (i.e., impaired cerebration and abnormal slowing of the EEG).
Because of its CNS depressant effect, chlorpromazine should be used with caution in patients with chronic respiratory disorders such as severe asthma, emphysema and acute respiratory infections, particularly in children (1 to 12 years of age).
Because chlorpromazine can suppress the cough reflex, aspiration of vomitus is possible.
Chlorpromazine prolongs and intensifies the action of CNS depressants such as anesthetics, barbiturates and narcotics. When chlorpromazine is administered concomitantly, about ¼ to ½ the usual dosage of such agents is required. When chlorpromazine is not being administered to reduce requirements of CNS depressants, it is best to stop such depressants before starting chlorpromazine treatment. These agents may subsequently be reinstated at low doses and increased as needed.
Note: Chlorpromazine does not intensify the anticonvulsant action of barbiturates. Therefore, dosage of anticonvulsants, including barbiturates, should not be reduced if chlorpromazine is started. Instead, start chlorpromazine at low doses and increase as needed.
Use with caution in persons who will be exposed to extreme heat, organophosphorus insecticides, and in persons receiving atropine or related drugs.
Antipsychotic drugs elevate prolactin levels; the elevation persists during chronic administration. Tissue culture experiments indicate that approximately 1/3 of human breast cancers are prolactin-dependent in vitro , a factor of potential importance if the prescribing of these drugs is contemplated in a patient with a previously detected breast cancer. Although disturbances such as galactorrhea, amenorrhea, gynecomastia and impotence have been reported, the clinical significance of elevated serum prolactin levels is unknown for most patients. An increase in mammary neoplasms has been found in rodents after chronic administration of antipsychotic drugs. Neither clinical nor epidemiologic studies conducted to date, however, have shown an association between chronic administration of these drugs and mammary tumorigenesis; the available evidence is considered too limited to be conclusive at this time.
Chromosomal aberrations in spermatocytes and abnormal sperm have been demonstrated in rodents treated with certain neuroleptics.
As with all drugs which exert an anticholinergic effect, and/or cause mydriasis, chlorpromazine should be used with caution in patients with glaucoma.
Chlorpromazine diminishes the effect of oral anticoagulants.
Phenothiazines can produce alpha-adrenergic blockade. Chlorpromazine may lower the convulsive threshold; dosage adjustments of anticonvulsants may be necessary. Potentiation of anticonvulsant effects does not occur. However, it has been reported that chlorpromazine may interfere with the metabolism of phenytoin and thus precipitate phenytoin toxicity.
Concomitant administration with propranolol results in increased plasma levels of both drugs.
Thiazide diuretics may accentuate the orthostatic hypotension that may occur with phenothiazines.
The presence of phenothiazines may produce false-positive phenylketonuria (PKU) test results.
Drugs which lower the seizure threshold, including phenothiazine derivatives, should not be used with metrizamide. As with other phenothiazine derivatives, chlorpromazine should be discontinued at least 48 hours before myelography, should not be resumed for at least 24 hours post-procedure, and should not be used for the control of nausea and vomiting occurring either prior to myelography or post-procedure with metrizamide.
Long-Term Therapy: To lessen the likelihood of adverse reactions related to cumulative drug effect, patients with a history of long-term therapy with chlorpromazine and/or other antipsychotics should be evaluated periodically to decide whether the maintenance dosage could be lowered or drug therapy discontinued.
Antiemetic Effect: The antiemetic action of chlorpromazine may mask the signs and symptoms of overdosage of other drugs and may obscure the diagnosis and treatment of other conditions such as intestinal obstruction, brain tumor and Reye’s syndrome. (See WARNINGS).
When chlorpromazine is used with cancer chemotherapeutic drugs, vomiting as a sign of the toxicity of these agents may be obscured by the antiemetic effect of chlorpromazine.
Abrupt Withdrawal: Like other phenothiazines, chlorpromazine is not known to cause psychic dependence and does not produce tolerance or addiction. There may be, however, following abrupt withdrawal of high-dose therapy, some symptoms resembling those of physical dependence such as gastritis, nausea and vomiting, dizziness and tremulousness. These symptoms can usually be avoided or reduced by gradual reduction of the dosage or by continuing concomitant anti-parkinsonism agents for several weeks after chlorpromazine is withdrawn.
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