What is the dosing for Phenergan (promethazine)?

From the Guidelines

The typical dosing for Phenergan (promethazine) is 12.5 to 25 mg intravenously, infused slowly to minimize the risk of hypotension, with a total dose of 25-100 mg that may be used as an adjuvant to narcotics and benzodiazepines 1.

Key Considerations

• The dose of promethazine may need to be adjusted based on individual needs and medical conditions, and it is essential to follow the prescribed dose and consult a healthcare provider for specific guidance.
• The clinical effects of promethazine are evident within 5 minutes of intravenous administration, with a duration of action of 4 to 6 hours and a plasma half-life of 9 to 16 hours 1.

Administration Guidelines

• For intravenous administration, the dose should be infused slowly at a rate of 25 mg/min to minimize the risk of hypotension 1.
• The use of promethazine may require a reduction in the dosage of standard sedation agents, and it is crucial to monitor patients closely for potential adverse effects.

Important Notes

• Promethazine has been investigated as an adjunct for sedation during minor surgical and endoscopic procedures, and its antihistamine, sedative, antiemetic, and anticholinergic effects make it a useful agent in various clinical settings 1.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION Promethazine Hydrochloride Tablets USP are contraindicated for children under 2 years of age The average oral dose is 25 mg taken before retiring; however, 12.5 mg may be taken before meals and on retiring, if necessary. Single 25-mg doses at bedtime or 6.25 to 12. 5 mg taken three times daily will usually suffice. The administration of promethazine HCl in 25-mg doses will control minor transfusion reactions of an allergic nature. Motion Sickness The average adult dose is 25 mg taken twice daily For children, promethazine hydrochloride tablets, syrup, or rectal suppositories, 12. 5 to 25 mg twice daily, may be administered. Nausea and Vomiting ... The average effective dose of promethazine hydrochloride for the active therapy of nausea and vomiting in children or adults is 25 mg 12.5- to 25-mg doses may be repeated, as necessary, at 4- to 6-hour intervals. For nausea and vomiting in children, the usual dose is 0. 5 mg per pound of body weight, and the dose should be adjusted to the age and weight of the patient and the severity of the condition being treated. Sedation ... Administration of 12. 5 to 25 mg promethazine hydrochloride by the oral route or by rectal suppository at bedtime will provide sedation in children. Adults usually require 25 to 50 mg for nighttime, presurgical, or obstetrical sedation.

The dosing for Phenergan (promethazine) is as follows:

• Allergy: 25 mg taken before retiring, or 12.5 mg taken before meals and on retiring
• Motion Sickness: 25 mg taken twice daily for adults, and 12.5 to 25 mg twice daily for children
• Nausea and Vomiting: 25 mg for children and adults, with 12.5- to 25-mg doses repeated as necessary at 4- to 6-hour intervals
• Sedation: 12.5 to 25 mg at bedtime for children, and 25 to 50 mg for adults 2

From the Research

Dosing Information for Phenergan (Promethazine)

• The standard dosage of promethazine is 25 mg, which can have significant sedative effects, especially when used in conjunction with narcotic analgesics 3.
• Low-dose intravenous promethazine (6.25 or 12.5 mg) has been shown to be effective in relieving nausea and vomiting, with fewer sedative effects compared to the standard dosage 3, 4.
• A study comparing two differing doses of promethazine (6.25 mg and 12.5 mg) for the treatment of postoperative nausea and vomiting found that both doses were effective, but the lower dose resulted in less sedation 4.
• Oral and intramuscular doses of promethazine 25 mg have been shown to produce significant decrements in performance, approximately equivalent to an alcohol blood level of 25-50 mg% (one-two drinks) 5.
• Consecutive daily doses of promethazine have been found to affect day-time drowsiness, simple reaction time, and postural tremor, with reduced reaction time deficits and tremor response observed following the repeat dose 6.

Dosage Ranges

• For the management of allergic conditions, motion sickness, and nausea, the dosage range of promethazine is not explicitly stated in the provided studies.
• For the treatment of postoperative nausea and vomiting, dosages of 6.25 mg and 12.5 mg have been used, with both doses being effective 4.
• In studies examining the effects of promethazine on drowsiness and motor responses, dosages of 25 mg have been used 5, 6.