Active ingredient: Gabapentin 300 mg, 600 mg; tabs.
Indication: Postherpetic neuralgia (PHN)
Pharmacology: The mechanism by which gabapentin exerts its analgesic action is unknown but in animal models of analgesia, gabapentin prevents allodynia (pain-related behavior in response to normally innocuous stimulus) and hyperalgesia (exaggerated response to painful stimuli). Gabapentin is structurally related to the neurotransmitter gamma-aminobutyric acid (GABA) but has no effect on GABA binding, uptake or degradation.
In vitro studies have shown that gabapentin binds with high affinity to the α2δ subunit of voltage-activated calcium channels; however, the relationship of this binding to the effects of gabapentin remains to be elucidated. It is hypothesized that gabapentin antagonizes thrombospondin binding to α2δ-1 as a receptor involved in excitatory synapse formation and suggested that gabapentin may function therapeutically by blocking new synapse formation.
Clinical trials: The efficacy of Gralise in the management of PHN was demonstrated in a double-blind, placebo-controlled, multicenter study. This study enrolled patients with PHN persisting for at least six months following healing of herpes zoster rash and a minimum baseline pain-intensity score of at least 4 on an 11-point numerical pain rating scale ranging from 0 (no pain) to 10 (worst possible pain).
This 11-week study compared Gralise 1,800 mg once daily with placebo. A total of 221 and 231 patients were treated with Gralise or placebo, respectively. The study treatment including titration for all patients comprised a 10-week treatment period followed by one week of dose tapering. Double-blind treatment began with titration starting at 300 mg/day and titrated up to a total daily dose of 1,800 mg over two weeks, followed by eight weeks fixed-dosing at 1,800 mg once daily and then one week of dose tapering.
During the stable-dosing period, patients took three active or placebo tablets each night with the evening meal. During baseline and treatment, patients recorded their pain in a daily diary using an 11-point numeric pain rating scale. The mean baseline pain score was 6.6 and 6.5 for Gralise and placebo-treated patients, respectively. At study endpoint, treatment with Gralise statistically significantly improved the mean pain score from baseline.
Adults: Swallow whole; do not crush, split or chew tabs. Take once daily with the evening meal. ≥18 years: initially 300 mg on Day 1, 600 mg on Day 2, 900 mg on Days 3-6, 1,200 mg on Days 7-10, 1,500 mg on Days 11-14, titrate up to 1,800 mg on Day 15. Renal impairment: creatinine clearance (CrCl) 30-60 mL/min: 600-1,800 mg. CrCl <30 mL/min or on hemodialysis: not recommended.
Children: <18 years: not recommended.
Warnings/Precautions: Not interchangeable with other gabapentin products. Epilepsy. Increased risk of suicidal thoughts/behavior. Monitor for worsening of depression, suicidal thoughts/behavior, and unusual changes in mood/behavior. Renal impairment. Avoid abrupt cessation; if discontinuing, withdraw gradually over the course of one week or longer. Elderly. Pregnancy (Cat. C). Nursing mothers: not recommended.
Interactions: May affect or be affected by hydrocodone. Potentiated by morphine. Separate dosing of aluminum- or magnesium-containing antacids by at least two hours. May cause false-positive results with urine protein tests.
Adverse reactions: Dizziness, somnolence, headache, lethargy, peripheral edema, diarrhea, dry mouth, pain in extremity.
How supplied: Tabs 300 mg—30; 600 mg—90; 30-Day starter pack—78 (9 x 300 mg + 69 x 600 mg)
For more information, call 866.458.6389 or visit www.Depomedinc.com.