Nausea antagonists

The side effects or toxic effects that the calcium antagonists have in common are hypotension, facial flushing, headache, di22iness, weakness, sedation, skin rash, edema, constipation, and abdominal discomfort (nausea, vomiting, and epigastric pressure). 

Class II drugs are classical (3-adrenoceptor antagonists such as propranolol, atenolol, metoprolol or the short-acting substance esmolol. These drugs reduce sinus rate, exert negative inotropic effects and slow atrioventricular conduction. Automaticity, membrane responsiveness and effective refractory period of Purkinje fibres are also reduced. The typical extracardiac side effects are due to (3-adrenoceptor blockade in other organs and include bronchospasm, hypoglycemia, increase in peripheral vascular resistance, depressions, nausea and impotence. 

Dronabinol (tetrahydrocannabinol), the active principle from cannabis and synthetic cannabinoids, nabilone and levonantradol are effective in treating nausea and vomiting in cancer chemotherapy. The mode of action is unclear but appears to involve cannabinoid CBi receptors. Cannabinoids have been shown to reduce acetylcholine release in the cortex and hippocampus, and have been suggested to inhibit medullary activity by a cortical action. Inhibition of prostaglandin synthesis and release of endorphins may also be involved in the antiemetic effect. A review of trials of dronabinol, nabilone or levonantradol concluded that while the cannabinoids were superior to placebo or dopamine receptor antagonists in controlling emesis... 

For prophylaxis of acute chemotherapy-induced nausea and vomiting, the combination of a 5-HT3 antagonist and a corticosteroid is recommended for patients receiving highly eme-togenic cisplatin or non-cisplatin-based chemotherapy. 

Droperidol or a 5-HT3 receptor antagonist should be administered at the end of surgery to patients at high risk for developing postoperative nausea and vomiting. 

The histamine2-receptor antagonists or H2RAs (cimetidine, famotidine, nizatidine, and ranitidine) and proton pump inhibitors (omeprazole, esomeprazole, lansoprazole, pantopra-zole, and rabeprazole) reduce the amount of acid secreted into the stomach by gastric parietal cells. These agents are also helpful for nausea and vomiting related to gastric acid secretion. 

Apomorphine is approved for acute off episodes in patients with advanced stages of PD. The onset of effect is within 10 to 20 minutes and the duration of effect is about 60 minutes. It requires premedication with an antiemetic because it causes nausea and vomiting. Antiemetics that block central dopamine worsen the symptoms of PD, and 5-HT3 antagonists, such as ondansetron, can aggravate PD-related hypotension. Trimethobenzamide (300 mg three times daily) should be... 

Fever, rigors, chills, malaise headaches, myalgia Nausea, emesis Neutropenia Hepatic enzyme elevation Cutaneous—alopecia, transient, mild rashlike reaction Acetaminophen (APAP). NSAID if APAP is not effective. Meperidine for severe chills and rigors. Bedtime administration. 5-HT3 antagonist, prochlorperazine, metoclopramide, fluids Weekly complete blood count reduce dose by 30-50% Liver function tests (LFTs) weekly withhold treatment until LFTs normalize restart at 30-50% dose reduction reversible on dose reduction or cessation. Interferon is contraindicated in patients with psoriasis because exacerbation of psoriasis has been noted during IFN therapy. 

Moderate, high, and very high likelihood of nausea/vomiting—5-HT3 antagonist (as above) and dexamethasone (as above) benzodiazepine Low likelihood of nausea/vomiting—Compazine Very low likelihood of nausea/vomiting—Compazine only if needed ... 

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