GI PPT Flashcards
name some antacids
magnesium tricilicate, aluminium/magnesium hyrdoxide
indications for antacids
GORD, dyspepsia
MOA of antacids
neutralise gastric acid. prolonged effect if taken after food
side effects of antacids
diarrhoea (with magnesium salts), constipation (with aluminium salts), systemic alkalosis
indications of alginates
dyspepsia, GORD
name an alginate
alginic acid
MOA of alginates
reacts with gastric acid to form a foam that sits on top of the gastric contents and prevents it from reaching oesophageal mucosa in reflux
side effects of alginates
nausea, bloating, diarrhoea
name some H2 receptor antagonists
ranitidine, cimetidine
MOA of H2 receptor antagonists
Competitive inhibitors of histamine receptors on gastric parietal cells. This helps to reduce acid secretion and pepsin production
indications of H2 receptor antgonists
GORD, dyspepsia, peptic ulcers, prophylaxis for NSAID associated peptic ulcers
side effects of H2 receptor antagonists
GI disturbance, rash, gynaecomastia
name some PPIs
omeprazole, lansoprazole
indications for PPIs
GORD, dyspepsia, peptic ulcers, prophylaxis for NSAID associated peptic ulcers, eradication of H.pylori
MOA of PPIs
Administered as a pro drug, but is activated to irreversibly inhibit H+/K+ ATPase which prevents gastric acid secretion
side effects of PPIs
N&V, abdo pain, diarrhoea & constipation, headaches
contraindications of PPIs
Inhibit enzymes in liver important for metabolism of other drugs. Can lead to increased clinical effect of warfarin, clopidogrel, phenytoin
name some opioids used in treatment of diarrhoea
Codeine phosphate, diphenoxylate, loperamide
Important effects of PPIs and H2 receptor antgonists that must be known before start of treatment
they mask the signs of gastric cancer
MOA of opioids used in diarrhoea
bind to mu receptors in the intestinal wall. This prolongs transit time through inhibition of propulsive movements, allowing time for more water reabsorption
side effects of opioids
respiratory depression, N&V, drowsiness, constipation
indications of bulk forming laxatives
constipation
name some bulk forming laxatives
ispaghula husk, methylcellulose, sterculia, bran
MOA of bulk forming laxatives
contain a hydrophillic compound which retains water already in the bowel well and builds stool mass. Increased bulk encourages peristalsis and relieves constipation
side effects of bulk forming laxatives
abdominal distention, flatulence, GI obstruction
name some osmotic laxatives
macrogol, lactulose, magnesium salts, sodium acid phosphate
indication of osmotic laxatives
constipation
MOA of osmotic laxatives
based on osmotically active substances which draw water in from other areas and hold it in the stool. This helps to stimulate peristalsis
side effects of osmotic laxatives
abdominal cramps, flatulence, nausea
name some irritant/stimulant laxatives
senna, dantron, bisacodyl, docusate sodium, sodium picosulfate
indications for irritant/stimulant laxatives
constipation
MOA of irritant/stimulant laxatives
Increase electrolyte and water secretion into colonic lumen. This increases colonic content and stimulates peristalsis
side effects of irritant/stimulant laxatives
abdo pain, diarrhoea, melanosis coli (pigmentation of intestinal wall)
name some faecal softeners
arachis oil, docusate sodium, co-danthrusate
MOA of faecal softeners
increase penetration of intestinal fluid into faecal mass, softening the stool and allowing peristalsis more easily
side effects of foecal softeners
abdo pain, nausea, rash
indication of faecal softeners
constipation
Name some aminosalicylates
mesalazine, sulfasalazine
indications for aminosalicylates
UC - first line, Crohns - used if intolerant to corticosteroids and others (drug works topically but crohns is full thickness)
MOA of aminosalicylates
Deliver 5- aminosalicylic acid (5-ASA) to lumen of colon, which has antiinflammatory action. Reduce cytokine formation, infammatory mediators and free radical formation
side effects of aminosalicylates
sulfasalazine has a higher side effect profile and can also cause oligospermia. GI disturbance e.g. N&V, Diarrhoea, rash, AGRANULOCYTOSIS
Name some corticosteroids used for IBD
prednisolone, hydrocortisone, budenoside
indications for corticosteroids
UC - usually used in addition to aminosalicylates. Crohn’s - first line
MOA of corticosteroids
Bind to glucocorticoid receptors, enter the nucleus of the cell and alter gene expression. Upregulates anti-inflammatory genes and downregulates pro-inflammatory genes. Also have a mineralocorticoid effect, stimulating Na+ & H2O retention and K+ secretion
side effects of corticosteroids
Immunosuppression
Metabolic - diabetes, osteoporosis, skin thinning and bruising
Mood and behavioural changes
Mineralocorticoid actions - oedema, hypokalaemia, hypertension
sudden withdrawal leads to addisonian crisis
name some anti-TNF alpha antibodies
infliximab, adalimumab
indications of anti-TNF alpha antibodies
UC and Crohn’s
MOA of anti-TNF alpha antibodies
Inhibit the binding of TNF-alpha to it’s receptors, reducing production of pro-inflammatory cytokines, leucocyte migration, activation of neutrophils and eosinophils
side effects of anti-TNF alpha antibodies
GI upset
Hypersensitivity reactions,
Blood disorders - anaemia, thrombocytopenia, leucopenia
Worsening heart failure
name some antimuscarinic drugs
hyoscine, dicycloverene, propantheline
indications for antimuscarinic drugs
IBS
MOA of antimuscarinics
competetive inhibition of Ach which inhibits parasympathetic innervation of myenteric and submucosal plexuses. This reduces colonic motility and inhibits gastric emptying
side effects of antimuscarinics
constipation
transient bradycardia and tachycardia
urinary retention
name some antispasmodic agents used in IBS
mebeverine, peppermint oil, dicycloverine
MOA of antispasmodics in IBS
smooth muscle relaxants. Relieves gut spasm and abdo pain
side effects of antispasmodics
heartburn, perianal irritation, headaches
name some antifungals
nystatin, fluconazole, amphotericin
indications for nystatin
any candida infection
MOA of nystatin
It’s a polyene. Binds to a component of the fungal cell wall and form pores which allows ions to leak out. Can be fungistatic or fungicidal
side effects of nystatin
very little when used topically, only local irritation. Oral use can cause GI upset
indications for fluconazole
candiasis and cryptococcal infections
MOA of fluconazole
triazole antifungal. Inhibit a from of cytochrome P450 which is important in production of components of cell wall. This alters cell membrane fluidity and increases cell wall permeability
side effects of fluconazole
GI disturbance, headaches, hepatitis, hypersensitivity
indications for metronidazole
C.difficile, oral and gynae gram -ve bacteria, H.pylori & diverticulitis, protozoal infections
MOA of metronidazole
only effective in anaerobic bacteria. Diffuses into the cell, is reduced which produces nitroso free radicals to bind to DNA cause degradation and cell death.
side effects of metronidazole
GI upset
Hypersensitivity reactions
Long term - seizures, optic neuropathy
contraindications of metronidazole
drinking alcohol, people with severe liver disease
indications of vancomycin
gram +ve infection
C.difficile infection - used in antibiotic associated colitis if metronidazole is ineffective
MOA of vancomycin
inhibits cross-linking of peptidoglycan chains, inhibiting cell wall synthesis of gram +ve bacteria
side effects of vancomycin
thrombophlebitis at injection site
red man syndrome - generalised erythema, hypotension and bronchospasm
hypersensitivity
blood disorders
name some antihelminthic drugs
ivermectin, albendazole
indications of ivermectin
filariasis(elephantiasis), hookworm, S. stercoralis infection
MOA of ivermectin
acts on glutamate gated ion channels, causing an influx of Cl-, generating muscle hyperpolarisation and paralysis of filariae (worms)
side effects of ivermectin
itching, rash
indications of albendazole
cysts, S stercoralis, hookworm
MOA of albendazole
bind to parasitic tubulin, preventing its polymerisation into cytoskeletal microtubules
side effects of albendazole
GI disturbance, headaches
name some opioids
morphine, diamorphine, tramadol, fentanyl, codeine phosphate
indications of opioids
acute/chronic moderate to severe pain management
MOA of opioids
Activate mu receptors in CNS which then causes reduced neuronal excitability and pain transmission.
In medulla they reduce respiratory drive and breathlessness. They reduce sympathetic nervous activity
side effects of opioids
respiratory depression N&V constipation dependance withdrawal reaction
warnings of opioid use
reduce doses in hepatic and renal impairment
avoid in biliary colic as it worsens the pain
name some combination analgesics
co-codamol (paracetamol, codeine), co-dydramol (paracetamol, dihydrocodeine)
indications of combination analgesics
mild to moderate pain
MOA of combination analgesics
paracetamol is a weak inhibitor of COX enzyme, this action appears to increase the pain threshold.
codeine and dihydrocodeine are weak opioids, so have weak activation of mu receptors.
side effects of combination analgesics
same side effect profile of opioids
paracetamol OD causes hepatotoxicity
name some NSAIDs
ibuprofen, naproxen, aspirin
indications of NSAIDs
chronic/neuropathic pain that’s mild to moderate
MOA of NSAIDs
COX 1 and 2 inhibition. COX-2 is responsible for prostaglandin production which causes inflammation and pain
Side effects of NSAIDs
GI toxicity
Renal impairment
Increased risk of CV event
name some non-opioid, non-NSAID analgesics
amitriptyline, carbamazepine, capsaicin, pregabalin
indications for non-opioid, non-NSAID analgesics
chronic or neuropathic pain
MOA of amitriptyline
inhibit neuronal reuptake of serotonin and norepinipherine
side effects of amitryptiline
arrhythmias, convulsions, hallucinations, extrapyramidal symptoms
indications of carbamazepine for analgesia
first choice for trigeminal neuralgia (sudden severe face pain)
MOA of carbamazepine
inhibit neuronal sodium channels, stabilising resting potentials and reducing neuronal excitability
side effects of carbemazepine
GI upset
hypersensitivity
hyponatraemia
indications of capsaicin
localised neuropathic pain, symptomatic relief of osteoarthrtitis
MOA of capsaicin
reduces substance P during inflammation. Causes defunctionalisation of nociceptors by causing a hypersensitivity reaction on the skin
side effects of capsaicin
temporary pain at application site
redness
N&V
Indications of pregabalin for analgesia
second line (to duloxetine) for diabetic neuropathy, first line in other neuropathies
MOA of pregabalin
binds to calcium channels and inhibits calcium inflow into neuron. This inhibits neurotransmitter release and reduces neuronal excitability
side effects of pregabalin
drowsiness, dizziness, ataxia
name a H1 receptor antagonist anti-emetic
cyclizine
indications of H1 receptor antagonists
motion sickness and vertigo
can also treat post op and drug induced sickness
MOA of H1 receptor antagonists
Block H1 and Ach receptors in vomiting centre of medulla and prevent them communicating with the vestibular system
side effects of H1 receptor antagonists
drowsiness
dry mouth
palpitations
warnings of H1 receptor antagonsists
avoid in patients with hepatic encephalopathy and prostatic hypertrophy
name an antimuscarinic anti-emetic
hyoscine
indications of antimuscarinic anti-emetic
motion sickness
post-op vomiting
MOA of antimuscarinic anti-emetic
block the Ach (muscarinic) receptors in vomiting centre of medulla and prevent communication with the vestibular system
side effects of antimuscarinic anti-emetics
dry mouth
urinary retention
blurred vision
sedation
name some dopamine (D2)receptor antagonists
metoclopramide, domperidone
indications of D2 receptor antagonists
vomiting due to reduced gut motility
drug induced vomiting
vomiting in pregnancy
can be used for other causes of vomiting
MOA of D2 receptor antagonists
D2 receptors are the main receptors in CTZ, so antagonists of these help to prevent CTZ stimulation. D2 receptors are also present in the gut, and if blocked, this promotes gastric emptying and gut motility
side effects of D2 receptor antagonists
diarrhoea
metoclopramide - extrapyramidal symptoms like an acute dystonic reaction e.g. oculogyric crisis
name a phenothiazine
prochlorperazine
indications for phenothiazines
vomiting from vertigo
vomiting from radio and chemotherapy
other causes of vomiting
MOA of phenothiazines
blockade of D2 receptors in CTZ and gut, and to a lesser extent blockade of H1 and Ach receptors in vomiting centre
side effects of phenothiazines
rarely used because of side effect profile
drowsiness
postural hypotension
extrapyramidal symptoms
name a 5-HT3 receptor antagonist
ondansetron
indications for 5-HT3 receptor antagonists
anaesthetic and chemo induced vomiting
MOA of 5-HT3 receptor antagonists
There are lots of 5-HT3 receptors in CTZ, so blockage of these prevents stimulation of vagus nerve at CTZ and prevents it activating the vomiting centre. Serotonin is a key neurotransmitter released by the gut in response to emetogenic stimuli, so 5-HT3 antagonists prevent this.
side effects of 5-HT3 receptor antagonists
side effects are rare
constipation
diarrhoea
headaches
warnings for use of 5-HT3 receptor antagonists
don’t use in people with a prolonged QT interval. Avoid in patients using antipsychotics and SSRIs
name a neurokinin-1 receptor antagonist
aprepitant
indications for neurokinin-1 receptor antagonist
cytotoxic drug induced vomiting
MOA of neurokinin-1 receptor antagonists
Block NK1 receptors in CTZ, inhibiting the action of substance P
side effects of NK-1 receptor antagonists
fatigue
dizziness
diarrhoea or constipation
name a cannabinoid
nabilone
indications of cannibinoids
cytotoxic drug induced vomiting
MOA of cannibinoids
inhibit CB1 receptors in several areas of the CNS, reducing their ability to release serotonin
side effects of cannabinoids
sedation
hallucination & disorientation
dry mouth
name a corticosteroid anti-emetic
dexamethasone
indications of corticosteroid anti-emetics
cytotoxic drug induced vomiting
usually used as an additive
side effects of corticosteroid anti-emetics
insomnia
indigestion
agitation
name some crystalloid solutions
0.9% NaCl
5% glucose
hartmann’s solution (comound sodium lactate)
indications of crystalloid solutions
fluid resuscitation and maintenance
MOA of hartmanns solution
contains NaCl, CaCl2, KCl, sodium lactate and water and is used to replace elcrolytes
side effects of hartmann’s solution
hypervolaemia
hyperkalaemia
hypercalcaemia
hypersensitivity
side effects of 09% NaCl
oedema
hypertension
hypernatraemia
side effects of 5% IV glucose
electrolyte imbalance
polyuria
oedema
