From the Research
Phenergan (promethazine) should be dosed at 6.25 mg intravenously for the treatment of nausea and vomiting, as this dose has been shown to be as effective as higher doses with fewer adverse effects. This recommendation is based on the study by 1, which compared the use of promethazine 6.25 mg intravenous with promethazine 12.5 mg intravenous among adult ambulatory surgery patients to control established postoperative nausea or vomiting (PONV). The study found that 97% of subjects reported total relief of nausea with a single administration of promethazine at either dose, and that promethazine 6.25 mg resulted in less sedation compared to the 12.5 mg dose.
Key Points
- The dose of 6.25 mg is effective for treating nausea and vomiting
- This dose has fewer adverse effects compared to higher doses
- The study by 1 supports the use of 6.25 mg promethazine for PONV
- Other studies, such as 2 and 3, also support the use of low-dose promethazine for nausea and vomiting
Considerations
- Elderly patients may require lower doses due to increased sensitivity to the medication's effects
- Patients should avoid driving or operating machinery after taking promethazine due to its sedative effects
- Promethazine has anticholinergic effects that can help reduce nausea by affecting the brain's vomiting center
- Side effects may include sedation, dry mouth, and constipation
Evidence
- The study by 1 found that promethazine 6.25 mg was as effective as promethazine 12.5 mg for controlling PONV, with less sedation
- The study by 2 found that low-dose intravenous promethazine (6.25 or 12.5 mg) relieved nausea and vomiting as effectively as intravenous ondansetron 4 mg
- The study by 3 found that a starting dose of 6.25 mg IV promethazine was as effective as higher doses and had fewer adverse drug reactions.