Pain Management - Neuropathic

Question 1

Drug targets for neuropathic pain

Answer 1

Reducing neuronal excitability and effects of nerve changes induced by damage
-Na channels, Ca channels, NDMA receptors

Question 2

Amitriptyline

• MOA
• min and max dose
• ADRs

Answer 2

Prevents reuptake of noradrenaline and seretonin at nerve endings

10-75mg at night

Dry mouth
Drowsiness
Urinary retention, constipation

Question 3

Pregabalin/gabapentin

• MOA
• min and max dose
• ADRs

Answer 3

VGCC binder

Pregabalin 150-600mg BDS/TDS
Gabapentin 300-3600mg TDS

Drowsiness
Dizzy, ataxia
N+V, indigestion

Question 4

Duloxetine

• MOA
• min and max dose
• ADRs

Answer 4

Potentiate descending inhibitory CNS pathways

60-120mg

For diabetic peripheral neuropathic pain

Nausea, dry mouth
Headache
Dizzy
Drowsiness

Question 5

Lignocaine patch

• MOA
• min and max dose
• ADRs

Answer 5

Topical anaesthetic that stabilises neuronal membranes, down regulates Na channels

For PHN

1 patch daily for 12 hrs

Dermatitis and irritation
Itch
Rash

Question 6

Renal function considerations

Answer 6

If renal function poor -amitriptyline (liver met)

Don’t use duloxetine CI in CKD S4

Question 7

Cardiac arrythmias/MI in past year

Answer 7

Gabapentin - drug of choice

Don’t use
amitriptyline
-can cause QT interval prolongation, arrythmias, MI

Duloxetine can increase HTN, HR

Question 8

Tablet burden and compliance

Answer 8

Amitriptyline - long half life
-can be given OD and still benefits if patient missed a dose

Gabapentin - short half life
-multiple tablets and multiple doses

Duloxetine - OD

Question 9

Dry mouth, urinary retention

Answer 9

Choose gabapentin

Amitriptyline is an anticholinergic