Adjuvant Analgesics

Question 1

Topiramate

Answer 1

Class: Oral anticonvulsant; neuropathic pain management.
Apps: seizures, neuropathic pain
Mech: modulate voltage-dependent Na+ channels, potentiate GABA inhibition, block excitatory glutamate neurotransmission, modulate voltage-gated Ca2+ channels
Effects: somnolence, nausea, numbness, weight loss

Question 2

Amitripyline

Answer 2

Class: TCA antidepressant; neuropathic main medication
Apps: depression; neuropathic pain. NOT for both simultaneously
Mech: NE and 5-HT reuptake inhibitor at presynaptic nerve ending. Has Na+ channel blocker and NMDA antagonist activities.
Effects: Anticholinergic effects (blurred vision, constipation, dry mouth, sedation, tachy, urinary retention). delirium in elderly

Question 3

Gabapentin

Answer 3

Class: Oral anticonvulsant; neuropathic pain
Apps: control seizures. Reduce pain in wide range of neuropathic pain (diabetic neuropathy, postherpetic neuralgia, shingles)
Mech: Efficacy not related to modulation of GABA system. Binds to subunit of volate activated Ca2+ channel, reducing Ca2+ current. Not metabolized, excreted in tact in urine.
Effects: dizziness & sedation

Question 4

Pregabalin

Answer 4

Class: Oral anticonvulsant. Neuropathic pain
Apps: adjunct therapy for partial seizures. Pain with fibromyalgia and spinal cord injury
Effects: dizziness & sedation

Question 5

Capsaicin

Answer 5

Class: Topical analgesic
Apps: Treat minor aches & pains of muscles/joints. Also for nerve pain
Mech: active component of chili peppers. Binds to thermal nociceptors, deplete substance P from sensory neurons
Effects: itching, stinging, erythema. low pt. compliance due to pain upon initial application