II. Precautions: Risk of Abuse

  1. Gabapentin and Pregabalin (Lyrica) is abused by patients on Opiates to potentiate CNS Opiate effects
  2. More than one quarter of Opiate patients have abused Gabapentin
  3. Pregabalin (Lyrica) is more potent with faster onset and has higher abuse potential than Gabapentin
  4. Smith (2012) Br J Gen Pract 62(601):406-7 +PMID:22867659 [PubMed]

IV. Safety

  1. Pregnancy Category C
  2. Excreted in Breast Milk

V. Mechanism

  1. GABA amino acid derivative (does not bind GABA-A or GABA-B receptors)
  2. Decreases excitatory neurotransmitter activity

VI. Metabolism

  1. Primarily renal excretion
  2. Half-life: 5 to 7 hours
  3. Therapeutic Dose: 4-8 ug/ml

VII. Adverse Effects

  1. Most common
    1. Sedation
    2. Dizziness
    3. Ataxia
  2. Other adverse effects
    1. Weight gain
    2. Nausea
    3. Fatigue
    4. Nystagmus

VIII. Preparations: Newer related agents

  1. Pregabalin (Lyrica)
    1. Indicated in Neuropathy
    2. More potent than Gabapentin, and possibly less Fatigue

IX. Dosing: Neuropathy in Adults

  1. Starting Dose
    1. Start at 300 mg orally at bedtime
    2. Advance to 300 mg orally three times daily (over 4-7 days)
    3. Plan to ultimately increase to 600 mg three times daily
    4. Patients tolerate starting 300 three times daily without titrating
    5. Fisher (2001) Neurology 56(6):743-8 [PubMed]
  2. Average Dose: 600 mg orally three times daily
  3. Maximum Dose: 1200 mg orally three times daily
    1. No increase in bioavailability above 1200 mg orally three times daily
    2. Minimal pain benefit above 1800 mg/day in most conditions studied
  4. Stopping (similar to Pregabalin)
    1. Taper off agent over 1 week or more
    2. Avoid stopping abruptly due to withdrawal symptoms

X. Dosing: Seizure Prophylaxis

  1. Age 3-12 years old
    1. Gabapentin 10-15 mg/kg (max 40 mg/kg) daily divided three times daily
  2. Age >12 years old
    1. Gabapentin 300-900 mg (max 1800) daily divided three times daily

XI. Drug Interactions

  1. No significant Drug Interactions

XII. Disadvantages

  1. Low potency as antiepileptic

XIII. References

  1. (2016) Crit Dec Emerg Med 30(9):24

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Cost: Medications

gabapentin (on 5/17/2017 at Medicaid.Gov Survey of pharmacy drug pricing)
GABAPENTIN 100 MG CAPSULE Generic $0.03 each
GABAPENTIN 250 MG/5 ML SOLN Generic $0.12 per ml
GABAPENTIN 300 MG CAPSULE Generic $0.04 each
GABAPENTIN 400 MG CAPSULE Generic $0.07 each
GABAPENTIN 600 MG TABLET Generic $0.10 each
GABAPENTIN 800 MG TABLET Generic $0.14 each
neurontin (on 6/1/2017 at Medicaid.Gov Survey of pharmacy drug pricing)
NEURONTIN 100 MG CAPSULE Generic $0.03 each
NEURONTIN 250 MG/5 ML SOLN Generic $0.12 per ml
NEURONTIN 300 MG CAPSULE Generic $0.04 each
NEURONTIN 400 MG CAPSULE Generic $0.07 each
NEURONTIN 600 MG TABLET Generic $0.10 each
NEURONTIN 800 MG TABLET Generic $0.14 each

Ontology: gabapentin (C0060926)

Definition (NCI_NCI-GLOSS) A substance that is being studied as a treatment for relieving hot flashes in women with breast cancer. It belongs to the family of drugs called anticonvulsants.
Definition (NCI) A synthetic analogue of the neurotransmitter gamma-aminobutyric acid with anticonvulsant activity. Although its exact mechanism of action is unknown, gabapentin appears to inhibit excitatory neuron activity. This agent also exhibits analgesic properties. (NCI04)
Definition (CSP) cyclohexananeacetic acid originally used as an anticonvulsant, found to have diverse CNS depressant actions.
Definition (PDQ) A synthetic analogue of the neurotransmitter gamma-aminobutyric acid with anticonvulsant activity. Although its exact mechanism of action is unknown, gabapentin appears to inhibit excitatory neuron activity. This agent also exhibits analgesic properties. Check for "http://www.cancer.gov/Search/ClinicalTrialsLink.aspx?id=38402&idtype=1" active clinical trials or "http://www.cancer.gov/Search/ClinicalTrialsLink.aspx?id=38402&idtype=1&closed=1" closed clinical trials using this agent. ("http://nciterms.nci.nih.gov:80/NCIBrowser/ConceptReport.jsp?dictionary=NCI_Thesaurus&code=C1108" NCI Thesaurus)
Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH C040029
SnomedCT 108402001, 386845007
LNC LP17989-2, MTHU012288
English 1-(aminomethyl)cyclohexaneacetic acid, 1-(aminomethyl)cyclohexaneacetic Acid, gabapentin (medication), GABAPENTIN, gabapentin [Chemical/Ingredient], Convalis, gabapentin, Gabapentin, Gabapentin (product), Gabapentin (substance)
Spanish gabapentina (producto), gabapentina (sustancia), gabapentina

Ontology: Neurontin (C0678176)

Definition (CHV) a kind of pain relieving drug
Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH C040029
English Neurontin, neurontin, Aventis brand of gabapentin, Parke Davis brand of gabapentin, Pfizer brand of gabapentin, Warner-Lambert brand of gabapentin