13) Pharmacology Flashcards
What class of drug is metformin? Describe the mechanism by which it exerts its effect.
Biguanide which work by:
- Reduced glucose uptake from the intestine
- Reduced glucose from gluconeogenesis at the liver
- Increasing insulin sensitivity and decreasing peripheral insulin resistance
N.b. also a role in balancing androgens/oestrogens which explains its role in PCOS
Name THREE ADRs of tolbutamide.
Sulphonylureas can cause:
- GI disturbance
- Hypoglycaemia
- Weight gain
- SiADH
- Liver dysfunction
- Hypersensitivity reactions
Give THREE instances where sulphonylureas should be avoided/used with caution.
- Acute porphyria
- Hepatic impairment
- Renal impairment
- Pregnancy
- Breast feeding
- Elderly
Describe the mechanism of action of gliclazide.
Sulphonylureas work by:
- Block the influx of K+ into the pancreatic Beta cell
- Change in membrane polarisation leads to influx of calcium
- The pancreatic Beta cell then is stimulated to release insulin
What should be done with a patient’s metformin prior to elective surgery.
Omit metformin on the morning of surgery and give insulin if required
Suggest THREE ADRs of the use of metformin.
Biguanides can cause:
- GI upset
- Lactic acidosis
- Reduced B12 uptake
- Renal impairment
Suggest TWO cautions when considering starting therapy with metformin.
- Lactic acidosis
- Renal function
Suggested TWO benefits of metformin MR.
Metformin modified release is considered superior to standard metformin as:
- Reduced GI ADRs
- Less pills have to be given, increasing adherence
Suggest THREE common drugs metformin may interact with.
- ACEi (hypoglycaemic effect enhanced)
- MAOi (hypoglycaemic effect enhanced)
- Cimetidine (excretion reduced)
Give THREE pieces of advice you would give to a patient starting metformin.
- Swallow the tablets whole and with a glass of water with or after meals
- Do not become pregnant on metformin
- Avoid alcohol during the period where you have taken metformin
Describe how sitagliptin works.
- DPP-4 antagonist which means less GLP-1 (as DPP-4 usually breaks down GLP-1) is broken down
- GLP-1 is a molecule (released by L cells) responsible for increasing insulin release and reducing glucagon release
Suggest THREE ADRs of sitagliptin.
- GI disturbance
- Peripheral oedema
- URTI
- Headache, drowsiness, dizziness
- Pancreatitis
- Stevens-Johnson syndrome
Give TWO situations where you would avoid prescribing a DPP-4 inhibitor.
- Pregnancy
- Breast feeding
- Ketoacidosis
Briefly describe the conditions under which exenatide can be prescribed.
Exenatide (GLP-1 agonist) can be prescribed if ONE of the following criteria are met:
- Triple therapy ineffective
- BMI over 35 AND symptomatic
- BMI under 35 AND have issues with insulin
Suggest THREE ADRs of exenatide.
- GI disturbance including abdominal pain & GORD
- Weight loss (decreased appetite)
- Headache/dizziness
- Hypoglycaemia
