Promazine is an active ingredient used for psychosis, drug withdrawal, states of agitation, or even for sedation before surgery. In combination with other agents, promazine is also used for severe to very severe pain, massive vomiting, and persistent itching.
What is promazine?
Promazine belongs to the group of phenothiazines and is a neuroleptic drug used to treat psychotic disorders. Its action is based on antagonism (reciprocal action) at dopamine receptors. In medicines, the active ingredient occurs as a white crystalline powder (promazine hydrochloride). It is readily soluble in water and has a half-life of up to 35 hours. However, drugs containing the active ingredient promazine are no longer available in Germany.
Pharmacological action
The effect of promazine as a neuroleptic is sedative and relaxing. It invokes antipsychotic, depressant, and antiemetic properties, which are due to antagonism at dopamine, histamine, serotonin, and muscarinic receptors and at adrenergic receptors. The receptors are thus blocked by promazine. The active ingredient has such a relaxing effect that nausea is inhibited, which is why the substance is used before operations and anesthesia. The active ingredient can also prevent cardiac arrhythmias caused by anesthetics. However, exactly how the effects of promazine are developed is still unknown.
Medical application and use
Promazine is used in psychosis, states of delirium, states of agitation and restlessness, and drug withdrawal. Applied it is also used for sedation before surgery and anesthesia. Due to its relaxing effect on the internal organs, it is also used in combination with other active ingredients in the treatment of severe to very severe pain, persistent itching and severe vomiting. It is commercially available in the form of dragées and can be taken up to 4 times a day (every 4 to 6 hours). In patients over 65 years of age, in severe depression, in bronchial asthma and chronic respiratory disorders, in liver damage, in severe hypotension, and in a variety of other conditions, medications containing the active ingredient should be administered only cautiously and in low doses under medical supervision.
Risks and side effects
Promazine should not be used in the presence of known hypersensitivity, in the case of comatose states due to alcohol or centrally depressant medications, in the presence of existing bone marrow depression, or in the presence of narrow-angle glaucoma. Furthermore, the active substance must not be used in infants under 3 months of age and in disorders of the hematopoietic system. Children 12 years of age and older – as well as pregnant and breastfeeding women – may take promazine under medical supervision after careful consideration of the benefits and risks. Promazine may cause several side effects that do not occur in everyone or may vary in severity. Side effects include drowsiness, headache, dizziness, lightheadedness, dry mouth, weight gain, constipation, water retention, allergic skin reactions with itching, listlessness, gastrointestinal problems, vision problems (including clouding of the eye lens and cornea), drop in blood pressure, movement problems (eg. (e.g., stiffness of muscles, slowing of movements), disturbances in bladder emptying, increased sensitivity to light, nerve dysfunction, menstrual disorders, depression, tremors, or even heart palpitations. The side effects usually also depend on the type of drug (e.g. tablets, injection) and the frequency with which it is taken. Furthermore, various interactions are known. For example, promazine enhances the effect of drugs used to depress the nervous system, drugs used to lower blood pressure, and the side effects of other neuroleptics and agents such as domperidone. Promazine decreases the effect of drugs used to treat Parkinson’s disease and diabetes. Ingestion of milk, tea, coffee or fruit juices in turn reduces the effect of promazine. If lithium is taken at the same time, symptoms of poisoning may occur under certain circumstances. Narcotics intensify the effect of promazine, increasing the risk of unconsciousness and coma. If suxamethonium is also taken at the same time as promazine, severe side effects may occur.Cramps may be the result of simultaneous use of promazine and drugs containing pentetrazole. If the physician prescribes tri- and tetracyclic antidepressants, these substances increase each other.
