The Action of Anti-Emetic Drugs

Isaacs, Bernard (1957) The Action of Anti-Emetic Drugs. MD thesis, University of Glasgow.

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1. A review of the literature of anti-emetic drugs showed that this title had been conferred on many substances by virtue only of their ability to prevent apomorphine-induced vomiting in dogs. The evidence that such drugs prevent vomiting in human disease was less acceptable. The new drug chlorpromazine was probably of value in cerebral tumour, pregnancy sickness, some forms of drug sickness and uraemia, but there was little support of its value in other forms of vomiting. 2. Personal experience with chlorpromazine in the treatment of thirty-six cases of vomiting from various causes was in conformity with these findings. 3. An experimental study in sixty normal human subjects showed that chlorpromazine was highly effective in preventing nausea and vomiting caused by apomorphine. Hyoscine also prevented vomiting due to apomorphine but did not prevent nausea. Atropine and promethazine were less effective in preventing vomiting than the other two drugs. 4. The emetic effect of apomorphine was prevented when the subject remained supine after the injection. An analysis of this effect showed that it was associated with reduction of afferent impulses in the recumbent position. 5. Subemetic doses of apomorphine caused inhibition of diuresis, due to release of antidiuretic hormone from the posterior pituitary. This effect was prevented by the supine position and by chlorpromazine. 6. Prolonged vestibular stimulation, insufficient to cause motion sickness, caused inhibition of diuresis due to release of antidiuretic hormone. This effect was prevented by chlorpromazine. 7. Nystagmus following vestibular stimulation was enhanced by apomorphine. Chlorpromazine prevented this effect of apomorphine, although it did not itself affect vestibular nystagmus. 8. It was suggested that apomorphine caused vomiting and antidiuresis in man by facilitating the effects of afferent stimulation in the autonomic centres of the hypothalamus, midbrain and bulb. Chlorpromazine blocked these facilitating actions of apomorphine. 9. The action of chlorpromazine is to block preferentially facilitating impulses in the reticular formation. Larger doses may also block normal afferent impulses. 10. Clinically chlorpromazine is of value as an antiemetic when sickness is caused by facilitation of afferent impulses. This is probably the case in many forms of drug-induced sickness. Chlorpromazine is of less value when vomiting is due to excessive afferent stimulation, as in motion sickness. Chlorpromazine is of no value when vomiting is caused by other mechanisms, as in radiation sickness. 11. Fuller knowledge of the action of anti-emetic drugs must await further studies of the pathogenesis of sickness in various clinical states.

Item Type: Thesis (MD)
Qualification Level: Doctoral
Keywords: Pharmacology
Date of Award: 1957
Depositing User: Enlighten Team
Unique ID: glathesis:1957-79196
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 05 Mar 2020 11:29
Last Modified: 05 Mar 2020 11:29

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