<p><strong>CNS Depressants</strong>: Promethazine hydrochloride (promethazine hydrochloride injection) may increase, prolong, or intensify the sedative action of central-nervous-system depressants, such as alcohol, sedative-hypnotics (including barbiturates), general anesthetics, narcotics, narcotic analgesics, tranquilizers, etc. When given concomitanty with promethazine hydrochloride (promethazine hydrochloride injection), the dose of barbiturates should be reduced by at least one-half, and the dose of narcotics should be reduced by one-quarter to one-half. Dosage must be individualized. Excessive amounts of promethazine hydrochloride (promethazine hydrochloride injection) relative to a narcotic may lead to restlessness and motor hyperactivity in the patient with pain; these symptoms usually disappear with adequate control of the pain.<br />
<br />
<strong>Epinephrine</strong>: Although reversal of the vasopressor effect of epinephrine has not been reported with promethazine hydrochloride (promethazine hydrochloride injection), it is recommended that epinephrine NOT be used in the case of promethazine hydrochloride (promethazine hydrochloride injection) overdose.</p>