II. Precautions: Risk of Abuse
- Gabapentin and Pregabalin (Lyrica) are abused by patients on Opiates 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]
III. Indications
- Neuropathic pain (peripheral nerve syndromes)
- Multiple Sclerosis
- Parkinson's Disease
-
Restless Legs Syndrome
- Effective in idiopathic RLS
- Effective in RLS among Hemodialysis patients
-
Epilepsy
- Generalized Tonic Clonic Seizures (rarely used)
- Partial Seizures (adjunctive agent)
- Bipolar Disorder
- Anxiety Disorder
-
Alcohol Dependence
- Doses of 600 mg orally three times daily appear to decrease Alcohol cravings
IV. Safety
- Pregnancy Category C
- Excreted in Breast Milk
V. Mechanism
- GABA amino acid derivative (does not bind GABA-A or GABA-B receptors)
- Binds alpha2-delta1 subunit of Central Nervous System voltage-gated Calcium channels
- Decreases excitatory neurotransmitter release and activity
VI. 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
VII. Adverse Effects: Standard Dosing
VIII. Adverse Effects: Overdose
- Acute Overdose: Sedative-Hypnotic effects
- Sleepy or lethargic
- Normal Vital Signs
- Chronic toxicity (especially with Renal Insufficiency)
- Progressive weakness
- Fatigue
- Altered Level of Consciousness
- Falls
IX. Preparations: Newer related agents
-
Pregabalin (Lyrica)
- Indicated in Neuropathy
- More potent than Gabapentin, and possibly less Fatigue
X. 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
XI. 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
XII. Drug Interactions
- No significant Drug Interactions
- However, Renal Insufficiency results in drug accumulation
XIII. Disadvantages
- Low potency as antiepileptic
XIV. References
- (2016) Crit Dec Emerg Med 30(9):24
- Lapoint (2021) EM:Rap 21(6): 16-7
Images: Related links to external sites (from Bing)
Related Studies
| 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 |
