Gabapentin is an anticonvulsive medication which first discovered in the 1970s in Japan.
Its original use was as a muscle relaxer and anti-spasmodic medication, but later, it was discovered the potential of the medication as anticonvulsive medication and as an adjunct to stronger anticonvulsants.
Gabapentin is an anticonvulsant medication that got FDA approval for partial seizure therapy in 1993. Currently, gabapentin has FDA approval for:
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Postherpetic neuralgia
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Adjunctive therapy in the treatment of partial seizures with or without secondary generalization in patients over the age of 12 years old with epilepsy, and the pediatric population, 3 to 12 year-olds with a partial seizure
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Moderate to severe restless leg syndrome (RLS) moderate to severe
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It also has off-label use for neuropathic pain, fibromyalgia, bipolar disorder, postmenopausal hot flashes, essential tremors, anxiety, resistant depressant and mood disorders, irritable bowel syndrome (IBS), alcohol withdrawal, postoperative analgesia, nausea and vomiting, migraine prophylaxis, headache, interstitial cystitis, painful diabetic neuropathy, social phobia, generalized tonic-clonic seizures, pruritus (itching), insomnia, post-traumatic stress disorder (PTSD), and refractory chronic cough.
In one placebo-controlled, retrospective study that investigated the effects of gabapentin on about 700 patients with refractory partial seizure disorder, there was an improvement in overall well-being in patients. The effect prompted a controlled investigation of the drug in primary psychiatric conditions.
An important benefit of gabapentin is that there is no interaction with valproate, lithium, and carbamazepine. Also, gabapentin has minor side effects.
Gabapentin in the Treatment of Anxiety and Depression
Gabapentin is rarely prescribed for patients with only anxiety disorder but is commonly prescribed for patients with bipolar disorder to reduce anxiety levels. Clinicians can also use it for patients who have anxiety and depression. Since anxiety is a coping skill, there is no drug to treat anxiety, but the medications used for this purpose make it possible to live at the moment, giving patients a chance to undergo anxiety treatment with non-pharmaceuticals. Even though the studies show that gabapentin is ineffective in the treatment of bipolar disorder, a case-control study with 60 patients in an acute phase of mania had a significant reduction in symptoms of anxiety with lithium and 900 mg of gabapentin. In another study with 21, mixed-state patients refractory to mood stabilizers received gabapentin (up to 2000 mg per day) for eight weeks, and patients with depressive symptoms had significant improvement in their CGI-BP (Clinical Global Impression-Bipolar) scores.
A meta-analysis of 7 trials pointed to gabapentin’s greater efficacy versus placebo in generalized anxiety disorder (GAD), although the effect size was approximately 0.35 for mental anxiety symptoms. A study of 153 patients who responded to the initial treatment of 450 mg per day for maintenance treatment of social anxiety disorder.
There are no clinical studies on the effectiveness of gabapentin as monotherapy or adjunctive therapy in major depressive disorders. However, there are case reviews that show some patients with depression who are refractory to standard antidepressants but showed therapeutic improvement when using gabapentin as adjunctive therapy.
In a randomized, double-blind study, with 130 patients that had under eye surgery, a one-time dose of 600 mg gabapentin significantly reduced the perioperative anxiety compared to a placebo. However, there was no significant difference compared to melatonin.