Vomiting hyoscine

These include atropine, scopolamine (hyoscine), trihexyphenidyl (benzhexol) and benzatropine. They block central muscarinic receptors involved in various afferent pathways of the vomiting reflex (Fig. 1). They have been used to control motion sickness, emesis in Meniere s disease and postoperative vomiting. Currently, hyoscine is largely restricted to the treatment of motion sickness where it has a fast onset of action but a short duration (4-6 h). Administration of hyoscine by transdermal patch produces a prolonged, low-level release of the drug with minimal side effects. To control postoperative vomiting, it should be applied >8 h before emesis is anticipated. 

Domperidone is a dopamine antagonist that acts on the chemoreceptor trigger zone. It can therefore be used as an anti-emetic in nausea and vomiting, for example, to counteract side-effects of cytotoxic therapy and to treat nausea associated with dopaminergic drugs used in Parkinson s disease. Unlike hyoscine butlybromide and antihistamines, domperidone is ineffective in motion sickness. 

CNS disorders Scopolamine and hyoscine are effectively used in the treatment of nausea, vomiting and motion sickness. Centrally acting anticholinergic/ antihistaminics e.g. trihexyphenidyl are used in parkinsonism. 

Transdermal scopolamine (hyoscine) was introduced in the 1980s as a convenient alternative for the prevention of motion sickness. It is also effective in reducing of nausea and vomiting after ear surgery but was not found to be useful in the prevention of vasovagal syncope (see Chapter 14). 

Antiemetics that act on the vomiting centre have antimuscarinic (their principal mode) and anti-histaminic action (hyoscine, promethazine) they alleviate vomiting from any cause. In contrast, drugs that act on the CTZ (haloperidol, ondansetron) are effective only for vomiting mediated by stimulation of the chemoreceptors (by morphine, digoxin, cytotoxics, uraemia). The most efficacious drugs act at more than one site (Table 31.1). 

Transdermal hyoscine is used by some anesthetists to minimize postoperative nausea and vomiting. The safety and efficacy of this form of treatment has been reviewed in an analysis of data from 23 trials involving 979 patients treated with hyoscine and 984 with placebo (2). The authors concluded that of 100 patients who are treated with hyoscine, 17 will escape postoperative nausea and vomiting that would otherwise have occurred however, 18 will have visual disturbances, 8 will complain of dry mouth, 2 of dizziness, and 1 will become agitated. Although these are not necessarily prohibitive problems, they certainly do need to be considered when choosing a drug for this indication. 

A transdermal delivery system has been developed for prevention of motion sickness and vomiting, using an adhesive patch for postauricular application the drug is released at a uniform rate for 72 hours. The adverse effects of this formulation are qualitatively typical of those reported for the oral and parenteral formulations of hyoscine and its congeners, although comparative studies suggest that the incidence is reduced with transdermal administration. Nevertheless, adverse effects involving the central nervous system, vision, bladder, and skin have been described, as have withdrawal symptoms after the patch is removed. 

Subsequently, Chan reported on twenty-four cases of overdose of a product containing valerian dry extract 75 mg, hyoscine hydrobromide 0.25 mg, and cyproheptadine hydrochloride 2 mg. Six patients developed vomiting, and fifteen underwent gastric lavage. Co-ingestants included alcohol (n = 10), cold products n = 3), hypnotics (n = 2), unknown drugs (n = 2), and gasoline (n = 1). Symptoms were mainly central nervous system depression and anticholin-... 

Datura stramonium Jimson weed, devil s weed, Thorn apple. Contains atropine, hyoscine, hyoscyamine. Stramonium tea and cigarettes used to be used for asthma. Dilated pupils, mania, red skin colour (dilated vessels and no sweating) thirst, tachycardia, vomiting, convulsions. 100-125 seeds lethal. Death uncommon. Datura was apparently used in India by poisoners to remove idiots from positions of high rank. 

Alkaloid related to atropine, hyoscine. Found in Solanum and similar species, including potatoes, tomato plant leaves, Jerusalem cherry plant. Effects gastroenteritis, vomiting, collapse, twitching, coma. Confusion and hallucination can last for several days. 

The most commonly used muscarinic receptor antagonist is scopolamine (hyoscine), which usually is administered as the free base in the form of a transdermal patch (transdee(M-scop). Its principal utility is in the prevention and treatment of motion sickness, although it also has some activity in postoperative nausea and vomiting. In general, anticholinergic agents have no role in chemotherapy-induced nausea. 

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