Promethazine: its composition and pharmacology

Promethazine

Chemical name-N,N,alpha-Trimethyl-10H-phenothiazine-10-ethanamine (as hydrochloride or camsilate). C17H20N2S

Pharmacological group of substance Promethazine-H1-antihistamines

Substance characteristic of Promethazine

Phenothiazine derivative. Crystalline powder, white or slightly yellow in color, odourless. Slowly oxidized in air, becoming blue. Very easily soluble in water, well soluble in alcohol.

Pharmacology

Promethazine: its composition and pharmacology

Pharmacological action – anti-allergic, local anesthetic, antihistaminic, antipruritic, antiemetic, sedative.
Competitively blocks H1-histamine receptors, has anti-exudative, anti-allergic, anti-inflammatory, local anesthetic effect. Reduces capillary permeability, swelling of mucous membranes, itching. It has adrenolytic, moderate peripheral and central cholinolytic effect. Inhibits histamine-N-methyltransferase, blocks central histamine H3-receptors. Depresses CNS, has sedative, anxiolytic, antipsychotic and hypnotic effects, lowers body temperature. It reduces excitability of vestibular receptors, inhibits labyrinth function, eliminates dizziness. The antiemetic effect is due to blockade of receptors of chemoreceptor zone of the medulla oblongata. It penetrates through the HEB. When administered 2 weeks before delivery, it may inhibit platelet aggregation in newborns. No mutagenic effects or adverse effects on fetal development have been found in experimental studies.

It is quickly and completely absorbed from the gastrointestinal tract. Oral administration reveals its effect after 15-60 min, i.m. administration – after 20 min, i.v. administration – after 3-5 min. Duration of action is 4-6 hours (after oral administration – up to 12 hours). Binds to blood plasma proteins by 65-90%. Metabolized in the liver and partially in the kidneys to form promethazine sulfoxides, N-desmethylpromethazine and other derivatives. It is mainly excreted in the urine, including as metabolites.

Application of the substance Prometazine

Promethazine: its composition and pharmacology

Allergic dermatoses, prurigo, eczema, exudative diathesis, urticaria, rash and other skin allergic reactions to drugs and chemicals, itching, allergic conjunctivitis, allergic rhinitis, pollinosis, stings of wasps, bees, scorpions, bumblebees, serum sickness, angioneurotic edema, false croup, asthmatic bronchitis, atopic bronchial asthma, anaphylactic and anaphylactoid reactions (as part of complex therapy), rheumatism with a pronounced allergic component; Meniere’s syndrome, dizziness, nausea and vomiting, motion sickness; anxiety, neurosis and neurosis-like conditions, psychosis, insomnia, extrapyramidal disorders (against the background of taking neuroleptics), trigeminal neuralgia, migraine, chorea, hyperthermia; premedication and postoperative period (as sedative, for artificial hibernation, to potentiate anesthesia and local anesthesia), study of gastric secretion (when used as a stimulant of histamine secretion).

Contraindications

Hypersensitivity (including to other phenothiazines), coma, concomitant use of MAO inhibitors and within 14 days after termination of their use, alcohol intoxication, hepatic and/or renal failure, pregnancy, lactation, episodic vomiting in children of unspecified genesis, early childhood under 2 months (for parenteral administration), childhood under 6 years old (for oral administration).

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