Pharm
Gabapentin
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Gabapentin
, Neurontin
See Also
Pregabalin
(
Lyrica
)
Precautions
Risk of Abuse
Gabapentin and
Pregabalin
(
Lyrica
) are abused by patients on
Opiate
s to potentiate CNS
Opiate
effects
More than one quarter of
Opiate
patients have abused Gabapentin
Pregabalin
(
Lyrica
) is more potent with faster onset and has higher abuse potential than Gabapentin
Lyrica
is categorized as
DEA Controlled Substance
Class V (and Gabapentin in several states)
Smith (2012) Br J Gen Pract 62(601):406-7 +PMID:22867659 [PubMed]
Indications
Neuropathic pain (
Peripheral Nerve
syndromes)
Diabetic Neuropathy
Postherpetic Neuralgia
(FDA approved)
Trigeminal Neuralgia
Cancer Pain Management
Multiple Sclerosis
Parkinson's Disease
Fibromyalgia
Restless Legs Syndrome
Effective in idiopathic RLS
Happer (2001) Neurology 57(9):1717-9 [PubMed]
Effective in RLS among
Hemodialysis
patients
Thorp (2001) Am J Kidney Dis 38(1):104-108 [PubMed]
Epilepsy
Generalized Tonic Clonic Seizure
s (rarely used)
Partial Seizure
s (adjunctive agent, FDA approved)
Bipolar Disorder
Anxiety Disorder
Post-Traumatic Stress Disorder
(
PTSD
)
Social Phobia
Generalized Anxiety Disorder
Alcohol Dependence
Doses of 600 mg orally three times daily appear to decrease
Alcohol
cravings
Opioid Dependence
Efficacy
Chronic Pain
(NNT 4.3)
Diabetic Neuropathy
(NNT 2.9)
Postherpetic Neuralgia
(NNT 3.9)
Safety
Pregnancy Category C
Excreted in
Breast Milk
Safe in liver disease (not hepatically metabolized)
Mechanism
GABA amino acid derivative (does not bind GABA-A or GABA-B receptors)
Binds presynaptic alpha2-delta1 subunit of
Central Nervous System
voltage-gated
Calcium
channels
Decreases excitatory
Neurotransmitter
release and activity
Metabolism
Bioavailability varies by dose
Larger doses have lower bioavailability
Divided doses result in better bioavailability
Primarily renal excretion in its original form (not metabolized)
Half-life: 5 to 7 hours
Therapeutic Dose: 4-8 ug/ml
Adverse Effects
Standard Dosing
Most common
Sedation
Dizziness
Ataxia
Other adverse effects
Weight gain
Nausea
Fatigue
Nystagmus
Withdrawal symptoms
Avoid stopping abruptly from higher doses (taper off)
Adverse Effects
Overdose
Acute
Overdose
:
Sedative-Hypnotic
effects
Sleep
y or lethargic
Normal
Vital Sign
s
Chronic toxicity (especially with
Renal Insufficiency
)
Progressive weakness
Fatigue
Altered Level of Consciousness
Falls
Preparations
Newer related agents
Pregabalin
(
Lyrica
)
Indicated in
Neuropathy
More potent than Gabapentin, and possibly less
Fatigue
Dosing
Neuropathy
in Adults
Starting Dose
Start at 300 mg orally at bedtime
Advance to 300 mg orally three times daily (over 4-7 days)
Plan to ultimately increase to 600 mg three times daily
Patients tolerate starting 300 three times daily without titrating
Fisher (2001) Neurology 56(6):743-8 [PubMed]
Average Dose: 600 mg orally three times daily
Maximum Dose: 1200 mg orally three times daily
No increase in bioavailability above 1200 mg orally three times daily
Minimal pain benefit above 1800 mg/day in most conditions studied
Stopping (similar to
Pregabalin
)
Taper off agent over 1 week or more
Avoid stopping abruptly due to withdrawal symptoms
Dosing
Seizure Prophylaxis
Age 3-12 years old
Gabapentin 10-15 mg/kg (max 40 mg/kg) daily divided three times daily
Age >12 years old
Gabapentin 300-900 mg (max 1800) daily divided three times daily
Dosing
Miscellaneous
Postherpetic Neuralgia
Day 1: 300 mg orally once
Day 2: 300 mg orally twice daily
Day 3: 300 mg orally three times daily
Titrate as needed for reduction in pain (up to 1800 mg/day)
Restless Leg Syndrome
Start 300 mg orally 2 hours before bed
Alcohol Dependence
Target dose 600 mg orally three times daily (start lower and titrate to dose)
Drug Interactions
No significant
Drug Interaction
s
However,
Renal Insufficiency
results in drug accumulation
Disadvantages
Low potency as antiepileptic
References
(2016) Crit Dec Emerg Med 30(9):24
LoVecchio (2022) Crit Dec Emerg Med 36(4): 36
Lapoint (2021) EM:Rap 21(6): 16-7
Wiffen (2005) Cochrane Database Syst Rev (3):CD005452 +PMID: 16034978 [PubMed]
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