General

Pronunciation
ga-ba-PEN-tin

Trade Name(s)

• Neurontin

Pregnancy Category
Category C

Ther. class.
analgesic adjuncts
anticonvulsants
mood stabilizers

Indications

• Partial seizures (adjunct treatment)

• Post-herpetic neuralgia

Unlabelled Use(s):

• Chronic pain

• Prevention of migraine headache

• Bipolar disorder

• Anxiety

Action

Mechanism of action is not known. May affect transport of amino acids across and stabilize neuronal membranes

Therapeutic Effect(s):

• Decreased incidence of seizures

• Decreased post-herpetic pain

Pharmacokinetics

Absorption: Well absorbed after oral administration by active transport. At larger doses, transport becomes saturated and absorption decreases (bioavailability ranges from 60% for a 300-mg dose to 35% for a 1600-mg dose)

Distribution: Crosses blood-brain barrier; enters breast milk

Metabolism and Excretion: Eliminated mostly by renal excretion of unchanged drug

Half-life: 5–7 hr (normal renal function); up to 132 hr in anuria

TIME/ACTION PROFILE (blood levels)

ROUTE	ONSET	PEAK	DURATION
PO	rapid	2–4 hr	8 hr

Contraindication/Precautions

Contraindicated in:
Hypersensitivity

Use Cautiously in:

• Renal insufficiency ( dose and/or dosing interval if CCr <=60 ml/min)

• Geri: Geriatric patients (because of age-related in renal function)

• OB: Safety not established for children <3 yr and pregnant women

• Lactation: Discontinue drug or bottle-feed

Adverse Reactions/Side Effects

CNS: confusion, depression, drowsiness, sedation, anxiety, concentration difficulties (children), dizziness, emotional lability (children), hostility, hyperkinesia (children), malaise, vertigo, weakness.

EENT: abnormal vision, nystagmus.

CV: hypertension.

GI: weight gain, anorexia, flatulence, gingivitis.

MS: arthralgia.

Neuro: ataxia, altered reflexes, hyperkinesia, paresthesia.

Misc: facial edema.

*CAPITALS indicates life-threatening.
*italic indicates most frequent.

Interactions

Drug-Drug

• Antacids may absorption of gabapentin

• risk of CNS depression with other CNS depressants, including alcohol, antihistamines, opioids, and sedative/hypnotics

• Morphine gabapentin levels and may risk of toxicity, dosage adjustments may be required

Drug-Natural Products
Kava, valerian, or chamomile can CNS depression

Route/Dosage

Epilepsy

• PO (Adults and Children >12 yr): 300 mg 3 times daily initially. Titration may be continued until desired (range is 900–1800 mg/day in 3 divided doses; doses should not be more than 12 hr apart). Doses up to 2400–3600 mg/day have been well tolerated.

• PO (Children >=5–12 yr): 10–15 mg/kg/day in 3 divided doses initially titrated upward over 3 days to 25–35 mg/kg/day in 3 divided doses; dosage interval should not exceed 12 hr (doses up to 50 mg/kg/day have been used).

• PO (Children 3–4 yrs): 10–15 mg/kg/day in 3 divided doses initially titrated upward over 3 days to 40 mg/kg/day in 3 divided doses; dosage interval should not exceed 12 hr (doses up to 50 mg/kg/day have been used).

Renal Impairment

• PO (Adults and Children >12 yr):
CCr 30–60 ml/min—300 mg twice daily;
CCr 15–30 ml/min—300 mg once daily;
CCr < 15 ml/min—300 mg once every other day; further adjustments are based on clinical response.

Post-Herpetic Neuralgia

• PO (Adults): 300 mg once daily on first day, 300 mg twice daily on second day, then 300 mg three times/day on day 3, may then be titrated upward as needed up to 600 mg three times/day.

Availability

• Capsules: 100 mg, 300 mg, 400 mg

» Cost:
Generic: 100 mg $64.96/270, 300 mg $169.97/270, 400 mg $209.98/270.

• Tablets: 100 mg, 300 mg, 400 mg, 600 mg, 800 mg

» Cost:
Generic: 600 mg $229.96/270, 800 mg $199.96/270.

• Oral solution (cool strawberry anise flavor): 250 mg/5 ml

» Cost: $130.10/470 ml.

Assessment

Seizures

• Assess location, duration, and characteristics of seizure activity

Post-herpetic Neuralgia & Chronic Pain

• Assess location, characteristics, and intensity of pain periodically during therapy

Migraine Prophylaxis

• Monitor frequecy and intensity of pain on pain scale

Lab Test Considerations

• May cause false-positive readings when testing for urinary protein with Ames N-Multistix SG dipstick test; use sulfosalicylic acid precipitation procedure

» May cause leukopenia

Potential Nursing Diagnoses

• Risk for injury (Side Effects)

• Chronic pain (Indications)

• Risk for aspiration (Adverse Reaction)

• Ineffective coping (Indications)

Implementation

PO: May be administered without regard to meals

» 600 mg and 800 mg tablets are scored and can be broken to administer a half-tablet. If half-tablet is used, administer other half at the next dose. Discard half-tablets not used within several days

» Gabapentin should be discontinued gradually over at least 1 wk. Abrupt discontinuation may cause increase in seizure frequency

Patient/Family Teaching

• Instruct patient to take medication exactly as directed. Patients on tid dosing should not exceed 12 hr between doses. Take missed doses as soon as possible; if less than 2 hr until next dose, take dose immediately and take next dose 1–2 hr later, then resume regular dosing schedule. Do not double doses. Do not discontinue abruptly; may cause increase in frequency of seizures

• Advise patient not to take gabapentin within 2 hr of an antacid

• Gabapentin may cause dizziness and drowsiness. Caution patient to avoid driving or activities requiring alertness until response to medication is known. Seizure patients should not resume driving until physician gives clearance based on control of seizure disorder

• Advise female patient to notify health care professional if pregnancy is planned or suspected or if she intends to breastfeed or is breastfeeding an infant

• Instruct patient to notify health care professional of medication regimen before treatment or surgery

• Advise patient to carry identification describing disease process and medication regimen at all times

• Refer patients with bipolar disorder to Manic-Depressive and Depressive Association for support

Evaluation/Desired Outcomes

• Decreased frequency of or cessation of seizures

• Decreased post-herpetic neuralgia pain

• Decreased intensity of chronic pain

• Decreased frequency of migraine headaches

• Increased mood stability

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