gabapentin

Source:  gabapentin    Tag:  gabapentin 300 mg capsule

gabapentin
( gab ah  pen' tin)
Neurontin

Pregnancy Category C

Drug class
Antiepileptic

Therapeutic actions
Mechanism of action not understood; antiepileptic activity may be related to its ability to inhibit polysynaptic responses and block posttetanic  potentiation.

Indications
·        Adjunctive therapy in the treatment of partial seizures with and without secondary generalization in adults and children 3–12 yr with epilepsy
·        Orphan drug use: Treatment of amyotrophic lateral sclerosis
·        Management of postherpetic neuralgia or pain in the area affected by herpes zoster after the disease has been treated
·         Unlabeled uses: Tremors of MS,  neuropathic pain, bipolar disorder, migraine prophylaxis

Contraindications and cautions
·        Contraindicated with hypersensitivity to  gabapentin.
·        Use cautiously with pregnancy, lactation.

Available forms
Capsules—100, 300, 400 mg; tablets—600, 800 mg; oral solution—250 mg/5  mL

Dosages
ADULTS
·         Epilepsy: Starting dose is 300 mg PO tid, then titrated up as needed.  Maintenance: 900–1,800 mg/day PO in divided doses tid; maximum interval between doses should not exceed 12 hr. Up to 2,400–3,600 mg/day has been used.
·         Postherpetic neuralgia: Initial dose of 300 mg/day PO; 300 mg bid PO on day 2; 300 mg  tid PO on day 3.
PEDIATRIC PATIENTS 3–12 YR
Initially, 10–15 mg/kg/day PO in three divided doses; adjust upward over about 3 days to 25–35 mg/kg daily in three divided doses in children  > 5 yr, and up to 40 mg/kg/day in three divided doses in children 3–4 yr.
GERIATRIC PATIENTS OR PATIENTS WITH RENAL IMPAIRMENT
Creatinine clearance ( mL/min)
Dosage (mg/day)
> 60
900–3,600 in three divided doses
> 30–59
400–1,400 in two divided doses
> 15–29
200–700 in one dose
< 15
100–300 in one dose
Postdialysis supplemental dosing, 125–350 mg PO following each 4 hr of dialysis.

Pharmacokinetics
Route
Onset
Duration
Oral
Varies
6–8 hr

Metabolism: Hepatic; T 1/2: 5–7 hr
Distribution: Crosses placenta; enters breast milk
Excretion: Urine, unchanged

Adverse effects
·         CNS:  Dizziness, insomnia, nervousness, fatigue,  somnolence, ataxia,  diplopia, tremor
·         Dermatologic:  Pruritus, abrasion
·         GI: Dyspepsia, vomiting, nausea, constipation, dry mouth
·         Respiratory: Rhinitis,  pharyngitis
·         Other: Weight gain, facial edema, cancer, impotence

Interactions
·        Decreased serum levels with antacids
·        False positives may occur with  Ames N-Multistix SG dipstick test for protein in the urine

Nursing considerations
Assessment
·         History: Hypersensitivity to  gabapentin; lactation, pregnancy
·         Physical: Weight; T; skin color, lesions; orientation, affect, reflexes; P; R, adventitious sounds; bowel sounds, normal output

Interventions
·        Give drug with food to prevent GI upset.
·        Arrange for consultation with support groups for people with epilepsy.
·         WARNING: If overdose occurs, hemodialysis may be an option.

Teaching points
·        Take this drug exactly as prescribed; do not discontinue abruptly or change dosage, except on the advice of your health care provider.
·        Wear a medical alert ID at all times so that any emergency medical personnel will know that you have epilepsy and are taking antiepileptic medication.
·        You may experience these side effects: Dizziness, blurred vision (avoid driving or performing other tasks requiring alertness or visual acuity); GI upset (take drug with food or milk, eat frequent small meals); headache, nervousness, insomnia; fatigue (periodic rest periods may help).
·        Report severe headache, sleepwalking, rash, severe vomiting, chills, fever, difficulty breathing.

Adverse effects in  Italic are most common; those in  Bold are life-threatening.