GI Pharmacology Flashcards
Discuss the drugs that are used to treat liver failure
think about the 4 main common conditions and how you would treat them !
(4)
1-Treating Ascites= build up of fluid in abdomen = diuretics ( spironolactone and furosemide)
2-Hepatic Encephalopathy ( mental confusion etc = Ammonia is systemic curation to the Brain and increase in GABA . For this treat the bleeding , give laxative lactulose , give vitamins, antibiotics )
3-Coagulopathy = give clotting factors and vitamin K
4-Hepatorenal syndrome = fluid and blood in the Wrong place due to vasodilation so give ADH to vasoconstrict.
Describe the principles of peptic ulcer disease therapy
a) what is a peptic ulcer and how is it caused
Peptic Ulcer =defect in duodenal mucosa -Due to acid and mucosal defence imbalance TREATMENT: 1-remove irritants (NSAIDS) 2-Antacids 3-Proton Pump Inhibitors 4-H2 receptor antagonist 5-Antibiotics
(blood in ur faeces called malaenia = black old blood from higher up the GI tract = darker blood from peptic ulcers)
List the potential areas of the parietal cell peptic acid secretion control that can be targeted by drugs in both predisposing and treating peptic ulcer disease
Gastric Parietal cell :
1-ACH receptor increases H+ secretion, hence more acidic in stomach
2-PGE2= Less secretion of H+ from the Lumen
3-Histamine 2 receptor = increases the H+ released to lumen
4-Gastrin increases H+ too
H+/K+ ATPase is a proton pump which can be inhibited
Compare proton pump inhibitors with histamine2-receptor antagonists in terms of mode of action, efficacy and adverse effects
(5)
-H2 blocks receptor which is acid producing stimuli , PPI block production at the source!
-H2 = decreases production for 8Hr, PPI= decreases production x>24hr
-Both = heart burn
-H2 = starts working in 15-30 min.PPi= begins working in 1hr but peak effect in 1-4hrs
-H2= relief for 12hr. PPI= relief for 24hr
PPI= irreversible , whereas H2 is a competitive antagonist
Discuss the diagnosis and treatment of helicobacter pylori infection relative to peptic ulceration
What is it ?
How do we test for this ?
How do we do Helicobacter Eradication ?
Peptic ulcer can be causes by gram negative Bacillus (Helicobacter pylori)= secrets inflammatory proteins , toxins which can cause Ulceration .
-urease enzyme in H.pylori which makes urea–>NH4 and CO2
HOW DO WE TEST FOR THIS?
1-C13 test + Urea breath test
2-Serology , to currently used by NICE
3-Upper GI endoscopy with biopsy , rapid urease test
4- Helicobacter Eradication Regimens ( 2 antibiotics + PPI) = triple therapy for 7 days
Apply the knowledge of peptic ulcer disease treatment to hypothetical clinical scenarios
(4)
If your stomach ulcer is caused by a Helicobacter pylori (H. pylori) bacterial infection, a course of antibiotics and a medication called a proton pump inhibitor (PPI) is recommended.
- Anti-inflammatory drugs (NSAIDs).
- H2 Receptor Antagonist
- Antacids
Proton pump inhibitor
(ends in ? what does it do and when is it used ?)
one really important precaution !?
Ends in -prazole
- Blocks the H+/K+ ATPase pump in the cell
-used in dyspepsia (indigestion)
+PUD
+GORD
-Be careful when prescribing ! can mask gastric cancer !!!
- vomiting , abdominal pain, diarrhoea, constipation , headache
Omeprazole
(normal side effects - name 3 )
Adverse drug reactions
INTERACTIONS
Proton pump inhibiter
-can mask gastric cancer , vomiting , abdominal pain, diarrhoea, constipation , headache
ADR:
1-increases risk of clostridium difficile
2-Hyponatraemia and Hypomagnesaemia
3-Hepatitus, Intestinal nephritis , blood disorders
4-increased risk of community acquired and hospital acquire pneumonia
Interactions :
1- Warfarin ( omeprazole and esomeprazole are weak CYP450 = increasing ANTI coagulant effect)
2-Clopidogrel( Hepatic pro-drug)= CYP450 inhibitors which have anti platelet effect
H2 receptor inhibitor
1-Cimetidine and Ranitidine
( stop the H2 receptor being activated , hence no cAMP –>NO pKA–>No Hydrogen potassium ATPase PUMP WORKING = LESS ACID
Constipation
treated by ?
causes ( the drugs which can cause this )
Treated by non pharmacological treatment : 1-increase fluid intake 2-imporve mobility 3-increase fibre intake 4-stop Constipating drugs 5-exclude the underlying pathology
CAUSES (DRUG WISE)
1-opoids, antacids including Ca2+, Al, anti depressants , anti musarinics
2-Anal fissure , peri anal absceses
3-benign colorectal disease
4-endocrine/ metabolic = hypercalacemia , hypothyroidism
5-Malignancy ( tumours )
LAXATIVES
3 main types
1) Osmotic laxative = draws in water to stool ie : Macrogois, Microvil
2) Stimulants = causes peristalsis = Senna
3) Bulk forming =causes stool to get bigger and softer = decussate
what is the phase 1 reaction of liver
what is phase 2 reaction of liver :
2
1-P450 monooxygenase & CYP450 2D6 enzymes =REDOX and they make drugs more reactive and hydrolytic reaction to make is WATER SOLUBLE and sticky
2) add the inactive groups to conjugate the groups = even more water soluble
enzyme inducers ?
PC BRAGS
1-At a cellular level , induces more Cytochrome enzymes = lasts longer and SLOW = increases enzyme production and hence drug metabolism increases so drug levels drop.
PC BRAGS
Phenytoin
Carbamazepine
Barbituates ( Brussel sprouts) Rifampicin Alcohol Glucocorticoids St. John's warts
CYP450 Enzyme inhibition
(Taehyung wants ON very easily )
(5)
FAST
1-Grapefruit juice
2-Protease Inhibition
3- Azoles
Causes the drug to increase as enzyme activity to break it down decreases.
Theophylline Warfarin Oxycodone Verapamil Erythromycin
cirrhosis signs and symptoms
5
1-Ascites 2-Encephalopathy 3-Coagulopathy (x>1.7 coagulation time ) 4-Hepatorenal Syndrome 5-Varices / portal HT
for every thing you score , you add one mark
CLASS A= 5-6 points ( easy )
B= 7-9 Points
C=10-15 points ( hard to treat )
