Promethazine warnings

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

List of warnings

warnings#CNS depression|CNS depression]

warnings#Respiratory depression|Respiratory depression]

warnings#Lower seizure threshold|Lower seizure threshold]

warnings#Bone-marrow depression|Bone-marrow depression]

warnings#Neuroleptic malignant syndrome|Neuroleptic malignant syndrome]

warnings#Pediatric patients|Pediatric patients]

warnings#Other considerations|Other considerations]

CNS depression

Promethazine HCl Syrup Plain may impair the mental and/or physical abilities required for the performance of potentially hazardous tasks, such as driving a vehicle or operating machinery. The impairment may be amplified by concomitant use of other central-nervous-system depressants such as alcohol, sedatives/hypnotics (including barbiturates), narcotics, narcotic analgesics, general anesthetics, tricyclic antidepressants, and tranquilizers; therefore such agents should either be eliminated or given in reduced dosage in the presence of Promethazine HCl. warnings#List of warnings|Return to top]

Respiratory depression

Promethazine HCl Syrup Plain may lead to potentially fatal respiratory depression. Use of Promethazine HCl Syrup Plain in patients with compromised respiratory function (e.g. COPD, sleep apnea) should be avoided. warnings#List of warnings|Return to top]

Lower seizure threshold

Promethazine HCl Syrup Plain may lower seizure threshold. It should be used with caution in persons with seizure disorders or in persons who are using concomitant medications, such as narcotics or local anesthetics, which may also affect seizure threshold. warnings#List of warnings|Return to top]

Bone-marrow depression

Promethazine HCl Syrup Plain should be used with caution in patients with bone-marrow depression. Leukopenia and agranulocytosis have been reported, usually when Promethazine HCl Syrup Plain has been used in association with other known marrow-toxic agents. warnings#List of warnings|Return to top]

Neuroleptic malignant syndrome

A potentially fatal symptom complex sometimes referred to as Neuroleptic Malignant Syndrome (NMS) has been reported in association with Promethazine HCl alone or in combination with antipsychotic drugs. Clinical manifestations of NMS are hyperpyrexia, muscle rigidity, altered mental status and evidence of autonomic instability (irregular pulse or blood pressure, tachycardia, diaphoresis and cardiac dysrhythmias). warnings#List of warnings|Return to top]

Diagnostic evaluation

The diagnostic evaluation of patients with this syndrome is complicated. In arriving at a diagnosis, it is important to identify cases where the clinical presentation includes both serious medical illness (e.g., pneumonia, systemic infection, etc.) and untreated or inadequately treated extrapyramidal signs and symptoms (EPS). Other important considerations in the differential diagnosis include central anticholinergic toxicity, heat stroke, drug fever and primary central nervous system (CNS) pathology. warnings#List of warnings|Return to top]

Management of NMS

The management of NMS should include 1) immediate discontinuation of Promethazine HCl, antipsychotic drugs, if any, and other drugs not essential to concurrent therapy, 2) intensive symptomatic treatment and medical monitoring, and 3) treatment of any concomitant serious medical problems for which specific treatments are available. There is no general agreement about specific pharmacological treatment regimens for uncomplicated NMS. warnings#List of warnings|Return to top]

Recurrences of NMS

Since recurrences of NMS have been reported with phenothiazines, the reintroduction of Promethazine HCl should be carefully considered. warnings#List of warnings|Return to top]

Pediatric patients

Promethazine HCl Syrup Plain is contraindicated for use in pediatric patients less than two years of age.
Caution should be exercised when administering Promethazine HCl Syrup Plain to pediatric patients 2 years of age and older because of the potential for fatal respiratory depression. Respiratory depression and apnea, sometimes associated with death, are strongly associated with Promethazine products and are not directly related to individualized weight-based dosing, which might otherwise permit safe administration. Concomitant administration of Promethazine products with other respiratory depressants has an association with respiratory depression, and sometimes death, in pediatric patients. warnings#List of warnings|Return to top]

Antiemetics

Antiemetics are not recommended for treatment of uncomplicated vomiting in pediatric patients, and their use should be limited to prolonged vomiting of known etiology. The extrapyramidal symptoms which can occur secondary to Promethazine HCl Syrup Plain administration may be confused with the CNS signs of undiagnosed primary disease, e.g., encephalopathy or Reyeâs syndrome. The use of Promethazine HCl Syrup Plain should be avoided in pediatric patients whose signs and symptoms may suggest Reyeâs syndrome or other hepatic diseases. warnings#List of warnings|Return to top]

Large dosages of antihistamines

Excessively large dosages of antihistamines, including Promethazine HCl Syrup Plain, in pediatric patients may cause sudden death. Hallucinations and convulsions have occurred with therapeutic doses and overdoses of Promethazine HCl Syrup Plain in pediatric patients. In pediatric patients who are acutely ill associated with dehydration, there is an increased susceptibility to dystonias with the use of Promethazine HCl. warnings#List of warnings|Return to top]

Other considerations

Administration of Promethazine HCl has been associated with reported cholestatic jaundice. warnings#List of warnings|Return to top]

Adapted from the FDA Package Insert.