TDM Drugs

Question 1

Dosage forms of carbamazepine

Answer 1

Oral

Rectal

Question 2

Maintenance dose of carbamazepine for epilepsy

Answer 2

Initially 100 to 200mg BD orally increased gradually to a max of 1.6-2g/day

Question 3

Time to reach steady state for carbamazepine

Answer 3

> 2 weeks when initiating therapy

Question 4

Therapeutic range for carbamazepine

Answer 4

4-10mg/l

Question 5

Toxic effects of carbamazepine

Answer 5

Incoordination 
Blurred vision 
Diplopia
Drowsiness
Nystagmus
Ataxia 
Arrhthmias 
Nausea and vomiting 
Diarrhoea 
Hyponatraemia

Question 6

Major route of elimination for carbamazepine

Answer 6

98% hepatic

Question 7

Which two drugs can decrease levels of carbamazepine

Answer 7

Phenytoin

Phenobarbital

Question 8

Name 5 drugs that can increase levels of carbamazepine

Answer 8

Erythromycin
Cimetidine 
Diltiazem
Verapamil 
Isoniazid

Question 9

True or false: carbamazepine induces its own metabolism

Answer 9

TRUE- this is why any changes in dose will take approx 1 week to produce a new steady state concentration

Question 10

Dosage forms of ciclosporin

Answer 10

Oral

IV infusion

Question 11

Toxic effects of ciclosporin

Answer 11

Nephrotoxicity 
Hepatotoxicity 
Muscle tremor 
Nausea 
Gingival hyperplasia 
Hypertension
Hyperkalaemia

Question 12

True or false: it does not matter if you change brands of ciclosporin

Answer 12

FALSE - stick to same brand due to different bioavailabilities

Question 13

Dosage forms of digoxin

Answer 13

Oral

Intravenous infusion

Question 14

Time to steady state for digoxin

Answer 14

1 week with normal renal function

Question 15

Therapeutic range of digoxin

Answer 15

1-2 mcg/L

Question 16

Toxic effects of digoxin

Answer 16

Nausea 
Vomiting 
Arrhythmias
Visual disturbances 
Weakness 
Lethargy

Question 17

Loading dose of gentamicin

Answer 17

3mg/kg IBW

Question 18

Time to steady state for gentamicin

Answer 18

12 to 24 hrs

Question 19

Therapeutic range for gentamicin

Answer 19

Peak: 5mg/kg-12mg/kg
Trough: <2mg/L

Question 20

Toxic effects of gentamicin

Answer 20

Otoxicity

Nephrotoxicity

Question 21

Major route of elimination for gentamicin

Answer 21

Renal excretion

Question 22

Major route of elimination for digoxin

Answer 22

Excreted unchanged in the urine. Hepatic metabolism to active metabolites

Question 23

Maintenance dose of lithium

Answer 23

500- 1200mg/day

Question 24

Lithium time to steady state

Answer 24

4-7 days

Question 25

Therapeutic range of lithium

Answer 25

0.4 to 1mmol/l

Question 26

Toxic effects of lithium

Answer 26

``` Nausea Vomiting Diarrhoea Weight gain Hand tremor Slurred speech Irritability Stupor Seizures Nephrotoxicity Increased reflexes ```

Question 27

Elimination half life

Answer 27

18-36 hours

Question 28

Major route of elimination for lithium

Answer 28

Freely filtered at glomerulus with 80% reabsorbed. No metabolism

Question 29

Volume of distribution for lithium

Answer 29

0.8L/kg

Question 30

7 factors that can increase plasma conc of lithium

Answer 30

``` Renal impairment Diuretics ACEI ARBs NSAIDs Hyponatraemia Intercurrent infection ```

Question 31

Three things that can decrease plasma conc of lithium

Answer 31

Theophylline Acetazolamide Cisplatin

Question 32

Should lithium be prescribed by brand

Answer 32

Yes