Pharmacology GI Flashcards
what class is orlistat
lipase inhibitor
what is usage orlistat
Used as an adjunct for obese patients with a BMI ≥ 30 to lose and maintain weight
cease treatment after 12 weeks if no more than 5% change.
what receptor does orlistat work on and is it anatgonist/agonist
lipase enzyme antagonist
what is MOA orlistat
Binds to lipases, therefore preventing the breakdown and absorption of fat (triglycerides) in the duodenum.
what are side effects orlistat
Oily spotting, flatus with discharge, faecal urgency, fatty/oily stool, increased defecation and faecal incontinence
what class is methylcellulose
antihypersensitive
what is methylcellulose usage
constipation, diarrhoe, obesity
what is methylcellulose MOA
Polysacharide polymer that forms a gel in the GIT and can’t be absorbed. This gel is formed in the SI and distends it. It stimulates peristaltic activity. Also thought to suppress appetite.
what is side effects methylcellulose
mild laxative effects. flatulence
what class is atrovastatin//simvastatin
HmG-coA reductase inhibitos (statins)
what is atrovastatin/simvastain usage
Lower LDL cholesterol
Familial and non-familial
Hypercholesteremia and mixed dyslipidemia
Hypertriglyceridaemia
what receptor is atrovastin/simvastatin and is it agonist/antagonist
HmG-coA reductase, competitive antagonist
what is atrovastatin/simvastatin MOA
HMG-CoA reductase is the rate limiting step in cholesterol biosynthesis. Statins competitively inhibit this enzyme, thereby lowering cholesterol levels.
Since cholesterol is essential for the prouction VLDL, we also see lower levels of triglycerides
what is atrovastatin/simvastatin side effects
Myalgia - common side effect of statin therapy
Diarrhoea, Joint pain, Nausea, Trouble sleeping, Stuffy nose, Sore throat
what class is cyclizine (no sedation)
anti-emetic, anti histamine
what is usage clyclizine (no sedation)
Nausea due to vertigo
Nausea due to motion sickness
Labrinythitis and menieres disease
where does cyclazine bind and its it antagonist/agonist
H1 receptor reverse agonist IT IS ANTAGONIST
what is cyclazine moa
H1 receptor has 2 states - active and inactive. The inverse agonist binds to the inactive form to reduce receptor activity
what is cyclazine side effects
drowsiness, prolong QT interval
what is promethazine(if sedation required) class
antihistamine, antipsychotic, sedative, and antiemetic
what is promethazine usage
Nausea due to vertigo
Nausea due to pregnancy
Nausea due to motion sickness. Labyrinthitis and meniere’s disease
what receptor is promaethezine and is it antagonistit/agonist
H1 receptor inverse agonist, H1 receptor anagonist
what is promoethazine moa
Bind to H1 receptors and so prevent the activation of the second messenger system stated on the left. This results in reduced hypersecretion, pruritis & sneezing
what is promethezine side effects
Drowsiness
Can’t see - blurred vision
Can’t pee - urinary retention
Can’t shit - constipation
Can’t spit - dry mouth
what class is Metoclopramide
Prochlorperazine
Domperidone
anti emetic prokinetic
what is usage of Metoclopramide
Prochlorperazine
Domperidone
Nausea due to pregnancy
Nausea due to migraine
Dysmotility dyspepsia
GORD
what receptor does Metoclopramide
Prochlorperazine
Domperidone work on and is it antagonist/agonist
D2 Gi receptor antagonist
(Dopamine Antagonist), dopamine receptor ANTAGONIST
what Metoclopramide
Prochlorperazine
Domperidone is MOA
Inhibit dopamine inhibition of ACh-induced contraction. Causes enhanced gastric emptying, reduction in the acid available to reflux and increased lower oesophageal sphincter basal tone
what is Metoclopramide
Prochlorperazine
Domperidone side effects
Parkinsonism
Tardive dyskinesia
Dystonia
Drowsiness, nervousness, agitation and anxiety
Increased pituitary prolactin release - impotence, galactorrhea, menstrual disorders
what class is metoclopramide
anti-ematic, prokinetic
what is metoclopramide usage
Nausea - migraine
Also used to treat GORD. DON’T USE REGULARLY. . Can also br used recreationally so be careful when prescribing
what is binding site of metoclopramide and is it antagonist/agonist
D2 receptor anatagonist , dopamine recepor antagonist
what is MOA of metoclopramide
Antiemetic action is due to its antagonist activity at D2 receptors in the chemoreceptor trigger zone (Ach induced contraction)
Agonist effect on peripheral 5HT3 and antagonist effect on muscarinic receptors to promote gastric emptying
what is side effects of metoclopramide
Tardive dyskinesia
Parkinsonism
Hyperprolactinaemia
what class is hydocine hydrobromide (can cross BBB) so
anti ematic, anti muscaranic, anti spasmotic
what is usage of hyoscine hydrobromide (can cross bbb)
H1 receptor antagonist (antimuscarinic)
what is hyoscine hydrobromide moa
Blocks muscarinic cholinergic M1 receptors in the vestibular nuclei, the nucleus of the solitary tract and the vomitting centre. (activation of these receptors required to trigger vomitting reflex)
what is hydoscine hydrobromide side effects
Can’t see - blurred vision
Can’t pee - difficulty passing urine
Can’t spit - Dry mouth
Can’t shit - constipation
what aprepitatnt (used before chemo) is usage
only used as prevention of nausea, not whilst patient has it. Usually in cancer chemo with moderate/hight emetogenic outcomes .
what receptor binds to aprepitant (used before chemo)
NK1 antagonist - supstance P (pain) can’t bind
what is dexamthesone class
Anti-emetic
Corticosteroid
Only antiemetic given IV. Used in combo with aprepitant
what is dexamethasone usage
Post-operative nausea
Nausea due to cancer chemotherpay and radiotherapy for those at low risk pre-treatment. Don’t use in diabetic patients as can induce glucose in blood
what is dexamethasone receptor and is it agonist/antagonist
minercorticoid- 5H3 receptor antagonist
what is dexamethasone MOA
unkown
what is prochloperazaine class
anti-emetic
what is prochloperazaine usage
post-operative nausea
what is prochloperazaine binding site and is it antaginist /agonist
D2 antagonist
what is prochloperazaine MOA
inhibit stimulation of the chemoreceptor trigger zone (CTZ)
what is graniestron/ondansetron
faecal softener
what is graniestron/ondansetron usage
Prevention and treatment of chemotherpay-induced nausea and vomitting . Some of the most effective at managing nausea and vomiting , really good at healping w acute phase, less w delayed phase . Also used in nausea and vomiting in opeates (ondansaterone first line w managmt of opiates)
what is granisetron/ondansetron receptor and is it agonist/antagonist
5HT3 antagonists
what is granisetron/odansetron MOA
Selective blockade of peripheral 5HT3 receptors on intestinal vagal afferents.
CNS actions at both the CTZ (chemoreceptor trigger zone) and vomitting centre (VC) also involved
Have peripheral and central effects
what is granisetron/ondansetron side effects
Transient, mild headache
Dizziness
Constipation
Small prolongation of QT interval
what is cisplatin usage
most likely to cause emertic episodes in 24 hours after administration in cancer chemo and radiotherapy
what is cisplatin MOA
What is the mechanism of cisplatin?
The mechanism of action of cisplatin has been associated with ability to crosslink with the urine bases on the DNA to form DNA adducts, preventing repair of the DNA leading to DNA damage and subsequently induces apoptosis within cancer cells.
what receptor does cisplatin bind to
N7 receptor on purine residues
what is cisplatin side effects
Anaemia; arrhythmias; bone marrow failure; electrolyte imbalance; extravasation necrosis; fever; leucopenia; nephrotoxicity (dose-related and potentially cumulative); sepsis; thrombocytopenia
what is arepitant class
antiematic
what is aripitent usage
Prevent nausea and vomitting caused by cancer chemotherapy with moderate or high emetogenic outcomes (PREVENTATIVE ONLY)
what is binding site of arepitant and is it antagonist/agonist
NK! receptor antagonist
what is arepitant moa
Binds to NK1 receptor in the brain at the CTZ and VC and antagonise them. It blocks the actions of substance P (neurokinin).
what is arepitant side effects
Fatigue
Constipation
Induces CYP3A4 - can shorten warfarin half life
effetcs of aspirin
inhibition of cyclose-oxigenase by aspirin leads to decreased production of thrombaxin A2
what do nsaids inhibit
clycloxygenase
what classes is Aluminium Hydroxide/ Magnesium carbonate/ Magnesium trisilicate
antacid and alginate
what is the usage of Aluminium Hydroxide/ Magnesium carbonate/ Magnesium trisilicate
provide GORD symtom relief
what is the 2 MOA of Aluminium Hydroxide/ Magnesium carbonate/ Magnesium trisilicate
Antacids are weak bases that react with gastric acid to neutralise the acid to water and a metal salt (also indirectly reduce pepsin activity)
Alginates form strong gels with divalent cations such as Ca2+ giving it strength and flexibility. Mode of action is physical rather than pharmalogical - gel physically keeps gastric acid down therefore supressing reflux and relieving GORD
what are Aluminium Hydroxide/ Magnesium carbonate/ Magnesium trisilicate side effect
Aluminium compounds - constipation
Magnesium Compounds - Diarrhoea
what are contraindications of Aluminium compounds - constipation
Magnesium Compounds - Diarrhoea
Diabetes - could affect glycemi control
Tetracycline antibiotics - react with 2+ ions antacids and inactivate antibiotic - leave at least 2 hours between adminsitration
Renal impairment - Mg and Ca accumulation could affect electrolyte balance. can contribute to bone disease and encephlopthy
Hypertension and congestive heart failure - Na could be in antacids- affect electrolyte balance. constipation w aluminium salts diarrhoea with magnesium salts so usually given in combination to counter the effects systemic alkolosis can occur with very large doses drug interactions: aluminium salts can bind to NSAIDs and tetracyclines in gut reducing absorption
what class is ranitidine
H2 receptor antagonist
what is ranitidine usage
Reduce gastric acid secretions
Heal ulcers. Dyspepsida . GORD
what receptor does ranitidine bind to and is it antagonist/agonist
Gs H2 receptor competitive antagonist
what is MOA of ranitidine
Ranitidine blocks the Gs H2 receptors on parietal cells lining the lumen of the stomach which reduces gastric acid secretion by 70% by preventing the following - normally H2 receptor actiation results in ↑ adenyl cyclase - ↑ cAMP - PKA activation - increased proton pump activity (K+ into parietal cell in exchange for H+;gastric acid out)
what are side effects ranitidine
Cimitidine, Gyneacomastia and/or galactorrhea
Confusion - primarily in elderly
CYP450 enzyme inhibition - interferes with metabolism of clopidogrel and warfarin
what class is Omeprazole
Clarithromycin
Amoxicillin
Metronidazole
quadruple therapy
what is usage of Omeprazole
Clarithromycin
Amoxicillin
Metronidazole
H.pylori infection that can’t be eradicated
what is MOA of Omeprazole
Clarithromycin
Amoxicillin
Metronidazole
MOA first 3 agents see below
metronidazole - T\his agent is reduced to an intermediate by receiving an electron from ferredoxin or flavadoxin, this activates the drug. The activated drug damages cells by forming protein and DNA adducts, inhibiting bacterial DNA synthesis and degrading existing DNA. The intermediate toxic metabolite is not produced in mammalian cells, ensuring antimicrobial selectivity.
what is Omeprazole
Clarithromycin
Amoxicillin usage
H.pylori infection
what is MOA of Omeprazole
Clarithromycin
Amoxicillin
Omeprazole see above
Clarithromycin MOA
Amoxicillin
This agent inhibits the final transpeptidation of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) by forming covalent bonds with penicillin-binding proteins that have transpeptidase and carboxypeptidase activities thus preventing formation of the cross links between the peptidoglycan matrix.
what class is Omeprazole
Clarithromycin
Amoxicillin
triple therapy
what c lass is omeprazole
PPI
what is usage of omeprazole
Reduce gastric acid secretions. Dyspepsia
Gastro-oesophageal reflux disease
NSAID-induced peptic ulcer (either gastric or duodenal)
Zollinger -Ellison syndrome
what is receptor omeprazole
bind to H+/K+ ATPase to irriversibly inhibit
what is MOA omeprazole
PPIs cause irreversible blockade of H+/K+ ATPase
Inhibit H+/K+ ATPase on parietal cells. Enterically coated omeprazoe is a weak base. At a physiological pH of 7.4, it is in its neutral form and passes freely into the cytoplasm of the parietal cell. Omeprazole passes into the acidic canaliculus where it is converted to its active form - sulfenamide.
Sulfenamide forms a covalent disulphide bond with H+/K+ ATPase, therefore inhibiting its activity, which results in prolonged supression (90-95%) of gastric acid secretion.
what is omeprazole side effects
Nausea
Diarrhoea
Headache
GI disturbance
Bone fractures - increased risk with long term use: hip, wrist and spine
what is loperamide class
Opiod
Anti-motility drug. Acts on myenteric plexus
what is loperamide usage
diarrhoea
what receptor is loperamide and is it antagonist/agonist
μ opioid receptor agonist
what is MOA of loperamide
Act on μ opiod receptors in myenteric plexus of the large intestine to inhibit acetylcholine release and reduce motility
what is bismuth subsalcylate class
Agent that modifies fluid transport
what is bismuth subsalcylate usage
diarrhoea
what is bismuth subsalcylate MOA
Stimulates absorption of fluids and electrolytes by the intestinal wall (anti-secretory action)
Reduces hypermotility of the stomach. Stimulates absorption of fluids + electrolytes by intestinal wall. Reduces hypermotility of stomach
what is ispaghula husk class
bulk forming laxative
what is isphalghula usage
constipation 1st line for short duration constipation
what is ispaghula husk MOA
Bulk-forming laxatives relieve constipation by increasing faecal mass which stimulates peristalsis.
what is lactulose class
Osmotic laxative. A non absorbable compund
what is lactulose usage
Constipation - 2nd line for short duration constipation
what is lactulose MOA
Absorbs water and increases stool bulk - this increases intestinal distension which increases peristaltic activity
Colonic bacteria use the hydrated material as a metabolic substrate - causes softening of the faeces. More water remains in gut.
what class is liquid paraffin
faecal softener
what is liquid paraffin usage
constipation
what si liquid paraffin MOA
Becomes emulsified with the stool and soften/lubricate it for easier passage out
what class is senna
Stimulant laxative - DON’T USE IN IBS
what is usage of senna
Constipation - 3rd line for short-duration constipation
what is senna MOA
Converted to active form by bacteria in the colon. Here they irritate the mucosa, causing low grade inflammation - this stimulates peristalsis and promotes the accumulation of water and electrolytes. Promotes accumulation of water and electrolytes
what is senna side effects
Excessive use can cause diarrhoea
Prolonged use increases risk of hypokalemia - this presents with non-specific symptoms such as tiredness and fatigue. Other symptoms include weakness of muscles, constipation and rhabdomyolysis.. CAN CAUSE LOW GRADE INFLAMMATION BY IRRITATING MUCOSA
what is hyoscine butylbromide class
Antispasmodic
Anti-muscarinic.
what is usage of hyoscine butylbromide
helps prevent cramping in IBS
what is hyooscine butylbromide receptor and is it antagonist or agonist
M3 receptor antagonist is the main one. Competitive H1 antagonist of M4 receptor
what is MOA of hyoscine butylbromide
Competetively antagonise action of ACh in enteric plexus - prevents ACh binding to M3 receptors - results in smooth muscle relaxation and relieves cramping and spasms of the gut. The relaxation improves normal gut functioning and peristaltic activity and relieves pain caused by trapped wind.
what is hyoscine hydrobromide side effects
Dry Mouth
Blurred vision
Cardiac arrhythmia
what is ppepermint oil/meberverine usage
IBS
how doe speppermint oil/meberverine work
Directly act on smooth muscle to relax it
what mesalazine class
Aminosalicylates
(anti-inflammatory)
what mesalazine usage
Mild to moderate UC and maintain remission
what is mesalazine MOA
Absorbed in LI - unknown MOA - thought to inhibit inflammatory mediators e.g. prostaglandins & cytokines
what class is prednisolone
Corticosteroid
(anti-inflammatory & immunosupressive)
what usage is prednisolone
Moderate to severe attacks of UC and Crohn’s disease
what recepto is prednistolone
glucocorticosteroid receptor
(nuclear receptor)
what MOA of prednisolone
Inhibits synthesis of inflammatory mediators
what class is infliximab
Antibodies to TNFα
what is usage of infliximab
Patients with Crohns who are resistant to conventional therapy
what moa of infliximab
TNFα causes activation of immune cells & release of inflammatory mediators - infliximab inhibits TNFα and induces remission in 1/3 of patients with Crohns who are resistant to conventional therapy
cimetidine
Gi block binds to H2 receptors
