Drugs Flashcards
Antacids
aluminium hydroxide
magnesium hydroxide
Reduce the symptoms of excessive gastric acid secretion by buffering HCL
GORD and dyspepsia
aluminum - constipation
magnesium - diarrhoea
NSAID how does this have a side effect in GI?
disrupt production of prostaglandins by inhibiting COX 1
This increases gastric acid secretion due to the lower levels of prostaglandins inducing the release of histamine
Prostaglandin E1
Misoprostol
Indicated for the prevention of a peptic ulcer
abdominal pain and diarrhoea
induces Labour
Proton pump inhibitors
omeprazole
irreversibly inhibit the proton pump (H+, K+) to reduce HCL release
GORD, peptic ulcer, Zollinger-ellison syndrome (gastrin secreting tumour of the pancreas)
used for H. pylori eradication
omeprazole + amoxy (metronidazole)+ clarithromycin
avoid NSAID
constipation, diarrhoea and headache
(anti histamine) Histamine type 2 receptor blocker
ranitidine
block histamine release secreted from enterochromaffin which reduces gastric acid secretion
Dyspesia
peptic ulcer
GORD
Hypotension, headache and diarrhoea(constipation)
Antihistamine (H1 receptor antagonists)
Cyclizine
antagonists at histamine H1 receptors in the brain
acute labyrinthitis, vomiting,
motion sickness
sedation - due to acting on H1 receptors
Anti muscarinic (muscarinic acetylcholine receptor antagonists)
scopolamine, hyoscine and mebeverine
antagonists at muscarinic acetylcholine M1 receptors in brain, inhibits GI movements and causes relaxation
antispasmodic
motion sickness + IBS
Dry mouth, blurred vision, sedation, urinary retention and tachycardia
5-HT3 receptor antagonists
ondansetron
blocks 5HT3 receptors that are prevalent in chemoreceptor trigger zone and also inhibit at the GI tract
chemotherapy, radiotherapy and post op induced sickness
headaches, constipation and diarrhoea
Dopamine receptor antagonists
Domperidone metoclopramide
block dopamine receptors (D2) in chemoreceptor trigger zone of medulla in hind brain + Gi tract
increase gastric motility
Increase lower O spinster tone, gastric emptying and duodenal peristalsis
Drug induced vomiting, vomiting in Gi disorders, GORD and gastroparesis
drowsiness, physiological disturbances AVOID IN GI OBSTRUCTION
Neurokinin-1 receptor antagonists
Fosaprepitant
antagonists at K1 receptors at GI tract and chemoreceptors of the medulla blocking the signal for vomiting
Adjunct treatment (5HT3 + dexamethasone?) to prevent nausea and vomiting for chemotherapy
constipation and headache
Antidiarrhoeal drugs
Loperamide diphenoxylate
Opitates that bind opiate receptors which has reduced effect on the brain.
decreases peristalsis + segmentation leading to constipation, sphincter contraction(resistance for urine to leave bladder) and increased fluid absorption
dirrhoea
sedation, constipation, uriniary retention and respiratory depression
potential for drug abuse as they are opiates
Laxitives - detail the mechanisms of action of ispaghula hulk, lactulose and Senna
Lactulose - osmotic laxative, leads to increased fluid in bowels
ispaghula husk - bulk forming laxative (bulk leads to peristaltic reflex
Senna - stimulant purgative - increases electrolyte then water secretion from the rectal mucosa as well as stimulation of the myenteric plexus (peristaltic reflex)
Peptide drugs
Linaclotide
Increase CL and bicarb in intestinal fluid and increases rate of intestinal transit
improves bowel movements and alleviates discomfort
IBS - with constipation in adults
diarrhoea
5-ASA (5-aminosalicylic acid)
Sulfasaline and mesalazine
anti-inflammatory drugs
Derived form salicylic acid and thought to trap free radicals
Acts from gut lumen, rapidly inactivated after reabsorption, shown to affect gut bacteria
Ulcerative colitis
diarrhoea nausea and cramps
What type of drug is best for rectal disease?
Suppositories
