Drug Monitoring

Question 1

ACE inhibitors / ARBs

Answer 1

• Efficacy → symptoms or blood pressure
• Safety → electrolytes (aim K⁺ < 6) + renal fxn 1-2 wks after dose change (accept 30% rise in Cr or 25% fall in eGFR)

Question 2

Antidepressants

Answer 2

• Symptom review @ 2 weeks and 4 weeks after starting treatment
• Change dose at 4 weeks if no effect
• Otherwise adjust at 6-8 wkly interval

Question 3

Azoles (eg. fluconazole)

Answer 3

• Monitor liver enzymes for toxicity in prolonged/high dose treatment

Question 4

Antipsychotics

Answer 4

• Monitoring for metabolic syndrome → weight, BP, glucose
• Clozapine may cause agranulocytosis → check FBC

Question 5

Beta Blockers

Answer 5

• Efficacy → symptoms, HR (aim 55-60)
• Safety → bradycardia / hypotension / bronchospasm
• Can mask symptoms of hypoglycaemia or thyrotoxicosis

Question 6

Bisphosphonates

Answer 6

• Efficacy:
  
  • Osteoporosis → DEXA scan at 1-2 yrs
  • Hypercalcaemia → calcium level + symptoms
• Safety → oseophagitis / osteonecrosis of jaw (don’t start until Vit D > 30ng/mil)

Question 7

Calcium Gluconate

Answer 7

• In hyperkalaemia → repeat 12-lead ECG + look for resolution of PR interval and QRS duration
• Repeat dose if needed

Question 8

Carbamazepine

Answer 8

• Efficacy:
  
  • seizure frequency monitoring
  • symptoms of pain in trigeminal neuralgia
  • mood stability in bipolar disorder
• Routine monitoring unlikely to coincide with hypersensitivity

Question 9

Digoxin

Answer 9

• Efficacy → symptoms + HR
• Safety:
  
  • periodic ECG (reverse tick is normal)
  • electrolytes → hypokalaemia + hypomagnesaemia increase risk of toxicity
  • renal impairment increases risk of toxicity

Question 10

Furosemide

Answer 10

• Efficacy → symptoms + signs of oedema, weight
• Safety → sodium, potassium + renal fxn

Question 11

Heparins

Answer 11

• LMWH → anti-factor Xa (pregnancy)
• UFH → APTT
• Both → platelet count should be monitored

Question 12

Iron

Answer 12

Expect Hb to increase by 20g/L per month

Question 13

Laxatives

Answer 13

Stool chart

Question 14

Metformin

Answer 14

• Efficacy → HbA1c
• Renal fxn measured annually (more freq in renal dysfunction)

Question 15

Methotrexate

Answer 15

• Safety → FBC, renal + liver fxn 1-2 wkly until treatment establishment + 3 monthly thereafter
• Treatment should not be started if liver tests abnormal
• Must be stopped immediately if drop in WCC/platelets until neutropenic sepsis excluded

Question 16

Phenytoin

Answer 16

• Wait 7-days after dose change before checking concentration
• Serum target → 40-80 umol/L

Question 17

Statin

Answer 17

• Aim for 40% reduction in non-HDL cholesterol
• Contraindicated/stop if liver enzymes x3 ULN
• ALT/AST checked 3 + 12 months after starting
• Check CK if at increased risk of myopathy

Question 18

Sulfonylureas

Answer 18

Monitor renal function (avoid accumulation)

Question 19

Vancomycin

Answer 19

• Clearance reduced in renal impairment so measure serum creatinine at baseline
• SEs → nephrotoxicity + ototoxicity

Question 20

Lithium

Answer 20

• Normal ref range 0.4-0.8 mmol/L
• Toxic effects manifest >1.5 mmol/L
• Measure serum lithium weekly after initiation and after dose changes until conc stables, then every 3 months after
• Hyponatraemia precipitates lithium toxicity

Question 21

Amiodarone

Answer 21

• Measure TFTs
• Baseline CXR required
• Monitor LFTs regularly
• Independent of renal function at least

Question 22

Sodium Valproate

Answer 22

• Associated w/ hepatotoxicity → measure baseline and regular LFTs