antiemetics,motility
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Transcript of antiemetics,motility
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ANTIEMETICS
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Regulation of vomitingRegulation of vomiting
• medulla oblongatamedulla oblongata
– the vomiting centre– chemoreceptor trigger zone (area postrema)
• emetogenic substances, apomorphine, morphine, chemotherapy, motion sickness
– Ach, histamine, 5-HT, Dop
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Clinical use of anti-emetic drugs:H1-receptor antagonists: cylizine - motion sickness
cinnarizine - motion sickness, vestibular disorders (e.g. Meniére´s disease)
promethazine - severe morning sickness of pregnancy (only if absolutely essential)
D2-receptor antagonists:phenothiazines (e.g. thiethylperazine) - vomiting causedby uraemia, radiation, viral gastroenteritis (drugs of choice);severe morning sickness of pregnancy (if absolutely essential)
metoclopramide - vomiting caused by uraemia, radiation, gastrointestinal disorders, cytotoxic drugs
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Muscarinic-receptor antagonists:hyoscine - motion sickness (drug of choice)
5-HT3receptor antagonists:ondansetron - vomiting caused by cytotoxic anticancerdrugs (drug of choice), postoperative vomiting; radiation-induced vomiting
Cannabinoids:nabilone - for vomiting caused by cytotoxic anticancer drugs
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laxatives
antidiarhoeal drugs
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LAXATIVESLAXATIVES• bulk laxativesbulk laxatives
– =increasing the volume, not absorbed– methylcelulose, agar, psyllium seeds– no serious unwanted effects
• osmotic l.osmotic l.– not absorbed, osmosis - distension of colon– magnesium sulphate, magnesium hydroxide, lactulose– ADR: flatulence, cramps, diarhoea, electrolyte dist.,
tolerance
• stimulant l.stimulant l.– stimulation of enteric nerves - secretion, motility– bisacodyl, senna preparations– ! only for short-term use - nerve reduction
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antidiarrhoeal agents Iantidiarrhoeal agents I
• secretion, motility, decreased absorption• ! fluid and electrolyte balance - rehydration
• antiinfective agents…gastroenteritis– sever cases of Campylobacter - erythromycin,
ciprofloxacin
• antidiarrhoeal agents
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antidiarrhoeal agents IIantidiarrhoeal agents II• antimotility agentsantimotility agents
– opiates, morphine - constipation, sphincter contraction– codeine, diphenoxylate, loperamide– ! drowsiness, dizziness, paralytic ileus
• adsorbentsadsorbents– adsorbing microorganisms and toxins– kaolin, pectin, charcoal
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motility stimulantsmotility stimulants• = prokinetic drug
• domperidone (Motilium) - D2 antagonist, also antiemetic oesophageal sphincter pressure…GERD
– ! hyperprolactinemia
• metoclopramide (Paspertin) - DA antagonist and Ach agonist– increases gastric emptying - GERD
– ! extrapyramidal side effects
• cisapride (Prepulsid) - 5-HT4 rec. agonist….Ach release
gut motility, no antiemetic action
– withdrawn due to QT prolongation