Pharmacology of CKD Flashcards
What is the action of mechanism of statins?
Give examples
Statins are a selective, competitive inhibitor of hydroxymethylglutaryl-CoA (HMG-CoA) reductase
This converts HMG-CoA to mevalonate in the cholesterol synthesis pathway in the liver.
By reducing hepatic cholesterol synthesis, an upregulation of LDL-receptors and increased hepatic uptake of LDL-cholesterol from the circulation occurs.
Drug examples: Simvastatin, atorvastatin
What is the target for statins?
hydroxymethylglutaryl-CoA (HMG-CoA) reductase
What are side effects of statins?
Muscle toxicity - likelihood increases with higher doses and in certain patients at increased risk of muscle toxicity.
Constipation or diarrhoea
Other gastrointestinal symptoms
What are statins useful for?
Decreasing LDL cholesterol
Effective at reducing the risk of adverse cardiac events in people
What should we ensure we do for patients on statins?
All patients should be regularly followed up to monitor for hyperkalemia and acute renal failure.
What interaction with statins should we be aware of?
Coadministration with potent CYP3A4 inhibitors (e.g. clarithromycin, erythromycin) may result in increased statin serum concentrations.
What is the mechanism of aspirin?
Irreversible inactivation of COX enzyme. Prevents oxidation of arachidonic acid to produce prostaglandins.
Reduction of thromboxane A2 in platelets reduces aggregation.
Reduction of PGE2
(i) at sensory pain neurons (reduces pain and sensation)
(ii) in the brain (decreases fever.)
What is the target for aspirin?
Cyclo-oxygenase (COX)
What are side efects of aspirin?
Dyspepsia
Haemorrhage
In the elderly, avoid doses >160mg daily (increased risk of bleeding) and co administer PPI if past history of peptic ulcer.
What is a downside of aspirin?
Blockade of COX1 in gastric mucosal cells reduces mucus/bicarbonate production which can expose the stomach lining to acid.
What can aspirin also be useful for?
most cost effective medicine for the prevention of secondary events of thrombosis.
What is the mechanism of trimethoprim?
Direct competitor of the enzyme dihydrofolate reductase. Inhibits the reduction of dihydrofolic acid to tetrahydrofolic acid (active form) – a necessary component for synthesising purines (A and G) required for DNA and protein production in bacteria
*in humans we get folate from diet so don’t need to synthesise folate
What is the target for trimethoprim?
Dihydrofolate reductase
Side effects of trimethoprim?
Diarrhoea
Skin reactions
What is trimethoprim often given alongside?
Often administered with sulfamethoxazole – known as co-trimoxazole (or TMP/SMX). In combination, they block two steps in bacterial biosynthesis of essential nucleic acids and proteins. This makes them bactericidal.
Individually they are bacteriostatic (stop replication but not kill them)
What do you need to monitor with administering trimethoprim?
Need to monitor blood counts with long term use or in those at risk of folate deficiency.
Also monitor serum electrolytes in patients at risk of developing hyperkalemia.
What is the mechanism of gentamicin?
Binds to the bacterial 30s ribosomal subunit disturbing the translation of mRNA leading to the formation of dysfunctional proteins.
What is the target for gentamicin?
30s ribosomal subunit
What are side effects of gentamicin?
Ototoxicity and nephrotoxicity
What is an important quality of gentamicin?
Gentamicin is an aminoglycoside antibiotic. Can pass through gram negative cell membrane in an oxygen dependent manner (why they are ineffective against anaerobic bacteria).