(also see rx for chemoRx induction) (Nausea and Vomiting)

• Vagal stimulation directly: gagging or stomach distention >20 mm Hg; uterine, bladder, renal distention; elevated CNS pressure

Rx:

Diphenhydramine (Benadryl) 25-50 mg po q 6 h, since both antihistamine and anticholinergic effects

• Labyrinthine stimulation causing cerebellar nausea, eg, motion sickness and all diseases affecting middle ear

Dimenhydrinate (Dramamine) best; scopolamine patch (Transderm V); or meclizine (Antivert) 25 mg po bid

• Medullary chemoreceptor trigger zone stimulation by: morphine, digoxin, tetracycline, oncologic chemotherapy, disulfiram (Antabuse), estrogens, uremia, radiation, cancer, toxins, anesthetics
• Phenothiazines like prochlorperazine (Compazine) 10 mg iv/im, better than chlorpromazine (Thorazine). (promethazine (Phenergan) no longer used parenterally due to potential for arterial ischemia induction
• Ondansetron (Zofran) 4-32 mg iv or 8-24 mg po; useful in chemoRx, pregnancy, other causes of N/V; peds dosing OK Marijuana (Nejm 1975;293:795); tetrahydrocannabinol po or smoked (Ann IM 1979;91:819), better than Compazine? (Nejm 1980;302:135 vs Ann IM 1979;91:825); works po in children (Nejm 2006;354:1698)
• Serotonin antagonists (Med Let 2004;46:27; Nejm 1990;322:810, 816), ondansetron, granisetron, palonosetron, or dolasetron, better than metoclopramide
• Droperidol (Inapsine) (Med Let 2002;44:53) 0.625-1.25 mg iv, esp for postop N⁺V; adv effects: QT prolongation and torsade