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Author: Admin | 2025-04-28
A reasonable safety profile.Promethazine (PHENERGAN)Disadvantage: Can cause tissue damage if extravasation, so generally shouldn't be given intravenously.Chlorpromazine (THORAZINE)It is not typically used for treatment of nausea/vomiting. However, chlorpromazine is overall quite similar to promethazine.Chlorpromazine could be considered as an alternative to promethazine, especially if intravenous administration is required.dosingProchlorperazine (COMPAZINE)5-10 mg IV q4-6 hours PRN (max 40 mg total daily).More: 📚 MedScape monograph on prochlorperazineChlorpromazine (THORAZINE)25 mg IM/IV q4-8 hours PRN.More: 📚 MedScape monograph on chlorpromazinePromethazine (PHENERGAN)12.5-25 mg PO/IM q4-6hr PRN (max 25 mg/dose, max 100 mg/day).25 mg per rectum q12 hours PRN.IV administration is avoided, since severe tissue damage can occur.(25841474)More: 📚 MedScape monograph on promethazinecautions & contraindicationsGeneral contraindications to these agents:Parkinson's diseaseSomnolence, with a risk of respiratory suppressionChlorpromazine (THORAZINE): May cause neutropenia, so it's contraindicated in leukopenia.All of these agents can prolong the QT interval (even prochlorperazine). (16860311, 32468935)metoclopramide(back to contents)general comments 💊Metoclopramide may be generally conceptualized as a combination of haloperidol plus a little ondansetron and some pro-kinetic activity (see receptor table above).Many antiemetics have both anti-D2 activity plus anticholinergic activity (e.g., olanzapine, prochlorperazine, promethazine). This intrinsic anticholinergic activity may reduce the rate of extrapyramidal symptoms caused by D2 antagonism (because anticholinergics can be used to treat extrapyramidal symptoms!). Agents with anti D2 activity that lack anticholinergic activity may tend to have the highest rate of extrapyramidal symptoms (e.g., haloperidol, droperidol, and metoclopramide).Metoclopramide's pattern of predominant D2 antagonism suggests that it will be an effective antiemetic, but it will also cause extrapyramidal side effects. Alternatively, if metoclopramide is dosed low enough to avoid any potential extrapyramidal side effects, then it will cease to work as an antiemetic (more on this below).StrengthsPro-kinetic properties may be beneficial for patients with gastroparesis.Lack of anticholinergic or antihistamine effects make metoclopramide non-sedating.May be useful for pregnancy-induced nausea/vomiting. (32468935)dosingDosing for nausea:Background on dosing: Traditionally,
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