Download ANTIEMETICS

ANTIEMETICS
Regulation of vomiting
• medulla oblongata
– the vomiting centre
– chemoreceptor trigger zone (area postrema)
• emetogenic substances, apomorphine, morphine,
chemotherapy, motion sickness
– Ach, histamine, 5-HT, Dop
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 caused
by 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
Muscarinic-receptor antagonists:
hyoscine - motion sickness (drug of choice)
5-HT3receptor antagonists:
ondansetron - vomiting caused by cytotoxic anticancer
drugs (drug of choice), postoperative vomiting; radiationinduced vomiting
Cannabinoids:
nabilone - for vomiting caused by cytotoxic anticancer drugs
laxatives
antidiarhoeal drugs
LAXATIVES
• bulk laxatives
– =increasing the volume, not absorbed
– methylcelulose, agar, psyllium seeds
– no serious unwanted effects
• osmotic l.
– not absorbed, osmosis - distension of colon
– magnesium sulphate, magnesium hydroxide, lactulose
– ADR: flatulence, cramps, diarhoea, electrolyte dist.,
tolerance
• stimulant l.
– stimulation of enteric nerves - secretion, motility
– bisacodyl, senna preparations
– ! only for short-term use - nerve reduction
antidiarrhoeal agents I
• secretion, motility, decreased absorption
• ! fluid and electrolyte balance - rehydration
• antiinfective agents…gastroenteritis
– sever cases of Campylobacter - erythromycin,
ciprofloxacin
• antidiarrhoeal agents
antidiarrhoeal agents II
• antimotility agents
– opiates, morphine - constipation, sphincter contraction
– codeine, diphenoxylate, loperamide
– ! drowsiness, dizziness, paralytic ileus
• adsorbents
– adsorbing microorganisms and toxins
– kaolin, pectin, charcoal
motility 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