Clinical Pharmacology Hyoscine, Hydrobromide… Antagonists Flashcards
causes of nausea and vomiting
alcoholism
drugs- opiates, antibiotics
infections - hepatitis, UTI
metabolic - addison’s disease, clinical vomiting syndrome
CNS disorders - meningitis, migraine
gastroduodenal- gastric cancer, gastroparesis
acute abdomin- appendicitis, pancreatitis
lifestyle treatments
reduce caffine, smoking, alcohol
avoid late meals to avoid lying supine after eating
avoid factors that relax oesophageal sphincter
take antacids and alginates
drugs to relieve vomiting
weak bases to neutralise stomach acid:
aluminium hydroxide
magnesium carbonate
magnesium trisilicate
prescribing anti-emetics
only prescribe when cause of vomiting is known
choice of specific drug is dependant on cause of vomiting
drugs for types of nausea
vertigo- H1 agonist: cyclizine, promethazine (sedation needed)
motion sickness- H1 agonist, hyosciene hydrobromide
pregnancy- H1 agonist: promethazine, D2 antagonists: prochlorperazine, metoclopramide
post operative- seratonin, antagonists, dexamethasone, prochlorperazine, cyclizine but may depend on other factors
migraine- D2 antagonists: prochlorperazine, metoclopramide
cancer chemotherapy: dexamethasone, lorazepam (low risk), aprepitant (high risk)
antimuscarinic
stimulation of muscarinic receptors (M1 and M3) in the vestibular nuclei, nucleus of solitary tract and vomiting centre induces vomiting
hyosciene blocks M1 and M3 and can stop vomiting
useful for motion sickness
given orally or transdermal patch
antimuscarinic side effects
dry mouth
constipation
blurred vision
difficulty passing urine
D2 antagonists
domperidone metoclopramide and prochlorperazaine
relieves nausea and vomiting and gastro-oesophageal reflux
increases GI motility by enhancing gastric emptying, reduces volume of acid
D2 antagonists side effects
parkinsonism and tardive dyskinesia and dystonia
drowsiness, nervousness, agitation and anxiety
anti-emetics: serotonin antagonists
granisetron, ondansetron
prevents chemo-induced nausea and vomiting
blocks serotonin receptors on interstinal vagal afferents
anti-emetics: serotonin antagonists side effects
mild headache
dizziness
constipation
prolongation of QT interval
anti-emetics: H1 receptor inverse agonist
cyclizine- used for motion sickness, labrinythitis and menieres disease
anti-histamine- blocks H1 receptors in its inactive phase
anti-emetics: H1 receptor inverse agonist side effects
drowsiness
prolong QT interval
pupil dilation
dry eyes, mouth
cant urinate
anti-emetics: corticosteroids
dexamethasone- used in children for tonsilectomy and adults with labyrinth disorder
can cause increase blood glucose
