Top 100 Drugs III Flashcards
In what state and where is iron best absorbed?
Fe2+ (ferrous state)
Duodenum and jejunum
Give 2 drugs that iron reduces absorption of?
Bisphosphonates
Levothyroxine
What are examples of bulk-forming laxatives?
Ispaghula husk
Methylcellulose
Sterculia
What are the major side effects of bulk-forming laxatives?
Mild abdominal distension
Flatulence
Faecal impaction
Bowel obstruction
What are examples of osmotic laxatives?
Lactulose
Macrogol
Phosphate enema
What are the indications for lactulose?
Constipation and faecal impaction
Bowel preparation prior to surgery/endoscopy
Hepatic encephalopathy
What conditions must phosphate enemas be used with caution?
Heart failure
Ascites
Electrolyte disturbances
(causes significant fluid shifts)
What are examples of stimulant laxatives?
Senna
Bisacodyl
Glycerol suppositories
Docusate sodium
When are stimulant laxatives contraindicated?
Bowel obstruction
What is the mechanism of action of lidocaine?
Blocks voltage-gated sodium channels
What are the indications for lidocaine?
- Local anaesthetic
- Antiarrhythmic drug in VT
- VF refractory to electrical cardioversion (although amiodarone more commonly used)
What are indications for macrolides?
- Respiratory and skin/soft tissue infection treatment where penicillin C/I due to allergy
- Severe and atypical pneumonia
- Triple therapy for H.pylori eradication
What is the mechanism of action of macrolides?
Blocks 50S ribosome
Prevents translocation
Inhibits protein synthesis
BACTERIOSTATIC
What are the major side effects of macrolides?
Irritant effects Abx- associated colitis Cholestatic jaundice QT prolongation Ototoxicity (high doses)
What drugs must macrolides be used in caution with?
- Drugs that require P450 metabolisation since macrolides (erythromycin and clarithromycin inhibit P450).
E.g. warfarin, statins. - Drugs that prolong QT interval e.g. antipsychotics, SSRIs, amiodarone, quinine, quinolones
What are the important adverse effects of metformin?
GI upset
Lactic acidosis
When is metformin contraindicated?
Severe renal impairment
Withhold acutely in AKI, severe tissue hypoxia, acute alcohol intoxication, hepatic impairment
How long prior to IV contrast injection must metformin be withheld for?
48 hours
What are the indications for methotrexate?
- DMARD
- As part of chemotherapy for leukemia, lymphoma and solid tumours
- Severe psoriasis
What is the mechanism of action of methotrexate?
Inhibits dihydrofolate reductase (prevents conversion of folic acid to tetrahydrofolate)