Prometazine is taken orally (after meals), administered intravenously, intramuscularly (deep into the muscle).
Adults: 3 to 4 times daily 12.5 to 25 mg and 25 to 50 mg at night (maximum single dose is 75 mg, daily 500 mg). Kinetosis – 12.5 – 25 mg 3 – 4 times a day orally. Nausea and vomiting – in the beginning 25 mg, further – 12.5 – 25 mg every 4 – 6 hours.
Children: 2 to 6 years of age – 12.5 mg, 6 to 14 years of age – 25 mg 3 to 4 times a day.
Seasickness syndrome prophylaxis once an hour before a trip: adults – 25-50 mg, children – 10-20 mg.
Parenterally (anesthesia practice, emergency cases): intramuscularly 0.5 – 1 mg/kg 3 – 5 times a day (in severe cases the initial dose may be 1 – 2 mg/kg), the maximum daily dose is 250 mg; intravenously (for hibernation) 0.15 – 0.3 mg/kg (infusion rate – 25 mg per minute, maximum allowable concentration – 25 mg/ml).
Preparation for surgery – the night before, 25 to 50 mg orally along with other drugs; on the day of surgery 2.5 hours before surgery, 50 mg intramuscularly (along with a cholinolytic and analgesic), possibly repeatedly injected 1 hour later; in children, the dose is 1.1 mg/kg.
Auxiliary treatment of anaphylactic shock – 10 – 20 mg intravenously slowly (after administration of epinephrine) and further during the next 1 – 2 days to prevent recurrence.
Use with caution in patients with cardiovascular disease, liver dysfunction, suppression of bone marrow hematopoiesis.
Promethazine may suppress the cough reflex, therefore caution is required in patients (especially children) with exacerbation of chronic respiratory diseases.
Periodic monitoring of peripheral blood cells and liver function parameters is required during long-term use.
Caution is required when using promethazine in the elderly because acute urinary retention and extrapyramidal disorders are possible.
Caffeine is recommended for prevention of central nervous system depression.
When promethazine is administered to children, care must be taken to ensure that the symptoms are not adverse reactions to this drug and that there is no concomitant undiagnosed Reye’s syndrome and encephalopathy.
In prolonged vomiting, promethazine should only be used as an antiemetic when the cause of the vomiting is known.
Prolonged use increases the risk of dental disease (periodontitis, dental caries, candidiasis) due to reduced salivary flow.
Promethazine increases the need for riboflavin.
Together with anxiolytics, narcotic analgesics (for complex preoperative preparation of patients) promethazine is used under strict medical supervision.
Prometazine may mask the ototoxic effects (dizziness, tinnitus) of the drugs used together.
If the drug is used together with sleeping pills and analgesics, the doses of the latter should be reduced.
Alcohol should be avoided during treatment.
Promethazine reduces the seizure threshold, which must be considered during the treatment of patients who are prone to seizures or who receive other drugs of similar effect together with promethazine.
Promethazine solution is not intended for subcutaneous or intra-arterial administration.
Some dosage forms of promethazine contain sodium metabisulfite, which may cause allergic reactions (including asthmatic and anaphylactoid reactions).
Increased blood glucose levels have been noted in patients who receive promethazine.
False-positive pregnancy test results may occur during promethazine therapy.
Promethazine should be discontinued 3 days before allergy testing to prevent distorted results of skin allergen scarification tests.
During treatment with promethazine, avoid driving vehicles and work requiring high concentration and quick psychomotor reactions.