Medication quick check| promethazine indications, dosage, black box warning

Pharmacokinetics

Pharmacological effect

It has antihistamine, sedative, anti-motion sickness, antiemetic and anticholinergic effects.

1) Antihistamine effect: compete with the H1 receptor of histamine released by tissues, which can antagonize the contraction and contracture of histamine on the smooth muscles of the gastrointestinal tract, trachea, bronchi or bronchiol, and relieve the spasmodic and congestive effect of histamine on the smooth muscles of the bronchi.

2) Antiemetic effect: may be related to the inhibition of the emetic chemical receptor area of the medulla oblongata.

3) Anti-motion sickness: may act on the vestibular and vomiting centers and medullary receptors through central anticholine properties, mainly to block the excitement of cholinergic synaptic vagus impulses in the nuclear area of the vestibular.

4) Sedative hypnotic effect: may be due to indirect reduction of the stress of the brainstem reticular ascending activation system.

Mechanism of action

Promethazine is a phenothiazine derivative that is a competitive H1 receptor antagonist but does not block the release of histamine. Structural differences with the antipsychotic drug phenothiazine lead to its relative lack of (1/10 of chlorpromazine) dopamine antagonist properties.

Domestically approved indications

Oral administration

1. Promethazine bile tablets: for coughs, whooping cough and its paroxysmal and spastic cough caused by colds.

2. Promethazine hydrochloride tablets:

1) Allergy of the skin and mucous membranes: suitable for long-term, seasonal allergic rhinitis, vasomotor rhinitis, allergic conjunctivitis caused by contact with allergens or food, urticaria, angioedema, allergic reactions to blood or plasma products, skin scratches. If necessary, it can be combined with epinephrine as an adjunct to this drug.

2) Motion sickness: prevention and treatment of motion sickness, seasickness, airsickness.

3) Sedation, hypnosis: suitable for preoperative, postoperative and obstetrics. In addition, it can also be used to alleviate the fear of adults, showing a light sleep state.

4) Treatment of nausea and vomiting: suitable for some anesthesia and postoperative nausea and vomiting, but also for the prevention and treatment of radiation disease or drug-induced nausea and vomiting.

5) Postoperative pain: can be combined with analgesics as an auxiliary medication.

Injection administration

1) Allergies to the skin and mucous membranes: suitable for long-term, seasonal allergic rhinitis, vasomotor rhinitis, allergic conjunctivitis, urticaria, angioedema, allergic reactions to blood or plasma products, skin scratches.

3) For anesthesia and adjuvant therapy before and after surgery, including sedation, hypnosis, analgesia, antiemetic.

4) For the prevention and treatment of radiopathic or drug-induced nausea and vomiting.

Domestic conventional dose

1. Promethazine bile tablets: oral. 12.5 mg 3 times daily.

1) Anti-allergic: 12.5 mg once, 4 times a day, take after meals and before bedtime, if necessary, 25 mg before bedtime;

2) Antiemetic: 25 mg at a time at the beginning, 12.5 to 25 mg every 4 to 6 hours if necessary;

3) Anti-vertigo: 25 mg at a time, 2 times a day if necessary;

4) Sedative hypnosis: 25 to 50 mg at a time, double if necessary.

Injectable administration: injections

1) Anti-allergic: 25 mg at a time, repeat after 2 hours if necessary; in case of severe allergies, intramuscular injection of 25 to 50 mg can be used, and the maximum amount should not exceed 100 mg.

2) In special emergencies, it can be diluted to 0.25% with sterile injection water and injected slowly intravenously.

3) Antiemetic: 12.5 to 25 mg at a time, repeat every 4 hours if necessary.

4) Sedative hypnosis: 25 to 50 mg at a time.

FDA black box warning

1. Respiratory depression: pediatric patients

Promethazine hydrochloride injection should not be used in pediatric patients under 2 years of age and may cause fatal respiratory depression. Cases of respiratory depression (including death) have been reported after marketing with promethazine in pediatric patients under 2 years of age. Caution should be exercised when injecting promethazine hydrochloride in pediatric patients 2 years of age and older.

2. Serious tissue damage (including gangrene)

(1) Regardless of the route of administration, promethazine hydrochloride injection can cause serious chemical stimulation and tissue damage, which may be caused by perivascular extravasation, intraarterial injection, and intraneuronal or perneuronal infiltration.

(2) Adverse reactions include burning sensation, pain, thrombophlebitis, tissue necrosis and gangrene. In some cases, surgical interventions including fasciotomy, skin grafting, and/or amputation are required.

3. Due to the risk of intravenous injection, the preferred route of administration of promethazine hydrochloride injection is deep intramuscular injection, and subcutaneous injection is prohibited.

The content is for reference only, please combine it clinically

Source | Medication Assistant app