High risk drugs and drugs that colour urine

Question 1

Which medicine may colour urine pink/orange

Answer 1

Phenindione

Question 2

Which medicine may colour urine red/yellow?

Answer 2

senna

Question 3

Which medicines may colour urine red?

Answer 3

rifampicin
co-dranthamer
levodopa (co-ben/ co-careldopa)
clofazimine
rifambutin

Question 4

Which medicine may colour urine reddish- brown

Answer 4

entacapone

deferiprone

Question 5

Which medicine may colour urine blue in some lights

Answer 5

triamterene (co-triamterzide/ frusene)

Question 6

Which medicine may colour urine pink?

Answer 6

nefopam

Question 7

Which medicine may colour urine yellow/brown

Answer 7

nitrofurantoin

Question 8

What do you know about digoxin?

Answer 8

Range: 1-2mcg/L
Sample: 6 hours post dose
Time to steady state: 5-7 days
Toxicity: N+V, abdo pain, bradycardia, delirium, yellow vision
Monitor: BP, ECG, renal function K (causes hypERkalaemia)

NOTE: hypokalaemia causes digoxin toxicity but the digoxin toxicity causes hyperkalaemia.

Question 9

What do you know about lithium?

Answer 9

Range: 0.4-1mmol/L
Sample: 12 hours post dose. Levels weekly then every 3 months.
Time to steady state: 4-7 days
Toxicity: tremor, convulsions, N+V, nystagmus, hyPERnatraemia
Monitor: TFTs, BMI, U+Es, renal function- every 6months,

NOTE: dehydration leads to toxicity.
patients should carry alert card.
NOTE: hyponatraemia can lead to toxicity but then toxicity causes hypernatraemia

Question 10

What do you know about phenytoin?

Answer 10

Range: 10-20 mg/L (5-20)
Sample: pre dose (can actually be taken any time as long as over 2 hours after dose)
Time to steady state: 7-28 days
Toxicity: N+V, nystagmus, ataxia, confusion, blurred vision
Side effects: hirsutism, rashes, acne, blood disorders, hepatotoxicity

NOTE: absorption impaired by feeds + calcium salts
bound to albumin in the blood
small changes in dose= massive changes in blood conc

Question 11

What do you know about carbamazepine?

Answer 11

Range: 4-12 mg/L
Sample: pre-dose (levels after 1-2 weeks)
Time to steady state: around 14 days
Toxicity: ataxia, nystagmus, blurred vision, arrhythmia
Side effects: hepatotoxicity, blood disorders, hyponatraemia, skin reactions

NOTE: Hans chinese/ Thai HLB*1502 alele- risk of SJS

Question 12

What do you know about theophylline?

Answer 12

Range: 10-20mg/L
Sample: post dose oral: 8-12 hours, IV 4-6 hours
Time to steady state: 2-3 days
Toxicity: intractable vommiting, arrhythmia, seizures, severe hypokalaemia, dilated pupils

Question 13

What do you know about amiodarone?

Answer 13

Loading dose: 200mg TDS then 200mg BD then 200mg OD
Side effects: corneal micro deposits, glares when driving at night, photoxicity, peripheral neuropathy, pulmonary fibrosis, hepatotoxicity, thyroid issues.
Monitoring: LFTs, TFTs, lung function baseline then every 6 months

NOTE: very long half life interactions can occur weeks after cessation.

Question 14

What do you know about methotrexate?

Answer 14

Avoid concomitant NSAIDs (increased methotrexate toxicity)
Side effects: blood disorders, hepatotoxicity, nephrotoxicity, pulmonary toxicity, GI toxicity (STOP if stomatitis)
Avoid handling tablets (all cytotoxics)
Teratogenic- contraception during + 6 months after for men and women.