Drug of the Day: Gabapentin

Question 1

What is the trade name of gapapentin?

Answer 1

Neurontin, Gralise

Question 2

What are the drug classes of gabapentin?

Answer 2

anticonvulsant; GABA analog

Question 3

What is the primary indication for gabapentin?

Answer 3

epilepsy

(adjunct treatment for partial seizures with or without generalization)

Question 4

What is the mechanism of action for gabapentin?

Answer 4

bind to affinity gabapentin sites in the brain

Question 5

For the mechanism of action, gabapentin binds to high affinity gabapentin sites in the brain which correspond to the presence of?

Answer 5

• voltage-gated calcium channels located pre-synaptically
• may modulate the release of excitatory neurotransmitters that lead to epileptogenesis

Question 6

The primary indication for gabapentin is epilepsy, but what are the other 4 indications?

Answer 6

1. neuropathic pain
2. diabetic peripheral neuropathy
3. fibromyalgia
4. post-operative pain

Question 7

What are the more frequent key adverse effects of taking gabapentin?

Answer 7

1. Asthenia (muscle weakness)
2. Ataxia (lack of voluntary muscle movemet)
3. Myalgia (muscle pain)
4. Diplopia (double vision)
5. Dizziness
6. Fatigue
7. Peripheral Edema (swelling)
8. Somnolence (sleepiness)
9. Tremor (involuntary muscle contraction)

Question 8

What are the undertermined key adverse effects of taking gabapentin?

Answer 8

1. angioedema
2. erythema multiforme

• Stevens-Johnson Syndrome

Question 9

One of the undertermined key adverse effects of taking gabapentin is ____ which can be life threatening and must seek medical attention.

Answer 9

angioedema

(swelling of extremities, face, lips, glottis, and larynx)

Question 10

What are the 3 monitoring parameters of taking gabapentin?

Answer 10

1. seizure activity
2. serum levels of concomitant anticonvulsants
3. potential for suicide

Question 11

What are the 4 key patient counseling points?

Answer 11

1. may be taken with or without food
2. if you miss a dose, do not double up
   
   • skip if less than 4 hours to next dose
3. do not exceed 12 hours between doses
   
   • do not discontinue abruptly
4. warn patients about drowsiness and driving

Question 12

For an adjunct to seizure management, what is the dosing for gabapentin?

Answer 12

300 mg po tid and increased up to 1800 mg/day

larger doses have been tolerated in clinical trials

Question 13

For an adjunct to diabetic neuropathy, what is the dosing for gabapentin?

Answer 13

900-3600 mg/day

Question 14

For an adjunct to neuropathic pain, what is the dosing for gabapentin?

Answer 14

300-3600 mg/day

Question 15

For an adjunct to neuropathic pain and post-herpetic neuralgia, what is the dosing for gabapentin?

Note: post-herpetic neuralgia is nerve pain due to damage caused by the varicella zoster virus.

Answer 15

• Day 1: 300 mg po qd
• Day 2: 300 mg po bid
• Day 3: 300 mg po tid
  
  • titrated up to 3600 mg/day based on response

Question 16

It is necessary to adjust the dosing of gabapentin for patients with renal insufficiency?

Answer 16

Yes