Patient Case Report: Gabapentin-Induced Hypoglycemia.

PURPOSE: Gabapentin is an analog of gamma-aminobutyric acid (GABA), but its complete mechanism is not well understood. Common adverse effects from gabapentin include somnolence, sedation, and dizziness. Hyperglycemia is listed as a possible adverse drug reaction in the labeling. Case reports describe hypoglycemia in patients with diabetes, peritoneal dialysis, and/or incomplete medication records. The following case report details a hypoglycemia episode as a potential result of a gabapentin use in a patient without diabetes. SUMMARY: A 47-year old, 68 kg, white female presented to the emergency department with altered mental status. Her blood glucose level was 33 mg/dL. Gabapentin was started 1 week prior to the hypoglycemia episode. Her past medical history, concomitant medications, and other laboratory findings were not likely causes of her severe hypoglycemia. CONCLUSION: Gabapentin appears to have effects on several voltage-gated calcium channels. Hypoglycemia may be due to gabapentin binding to the alpha2delta subunit of the calcium channels in the pancreas. Future research should investigate gabapentin and the potential for hypoglycemia.

Patient Case Report: Memantine for the Treatment of Occipital Neuralgia.

Occipital neuralgia (ON) is described as a shooting, stabbing pain in the posterior part of the scalp that involves the occipital nerve. The epidemiology and pathophysiology are uncertain, but ON is considered distinct from other headache types. At the time of this writing, memantine for the treatment of ON has not been described in the literature. The following details a case report of successful treatment of ON with memantine. A 64-year-old, 91-kg, White man presented with severe headache associated with ON. Previous trials of oral medications, acupuncture, or physical therapy did not provide relief. The patient reported 15 ON headache days per month, use of 18 sumatriptan tablets per month, and daily use of as-needed ibuprofen. Because of inadequate relief of ON from other treatments, memantine was started. After titration to memantine 10 mg by mouth twice daily, the patient reported he was "100% headache free" from his ON pain. The patient tolerated memantine well without adverse effects. This case report displays safe, effective, and novel treatment of ON with memantine 10 mg by mouth daily, twice daily. The known safety, tolerability, and pharmacodynamics of memantine may warrant its off-label use in future studies exploring efficacy in ON.

Cyclic vomiting syndrome: diagnostic approach and current management strategies.

Cyclic vomiting syndrome (CVS) is a disorder characterized by episodes of nausea and vomiting lasting for 1-5 days followed by asymptomatic periods. The etiology of CVS is unknown, but it shares similar characteristics to migraine headaches. CVS is generally classified as having four phases: prodromal, acute/vomiting/hyperemesis, recovery, and remission/interepisodic. Current management strategies include trigger avoidance, abortive and prophylactic medication therapies, and supportive care. The goal of therapy for the remission phase is prophylaxis of further episodes. Antidepressant, antiepileptic, and antimigraine medications show an overall reduction or remission of CVS symptoms in more than 70% of patients. This article provides a summary of diagnostic strategies and reviews current management strategies for CVS.

Brivaracetam: An Adjunctive Treatment for Partial-Onset Seizures.

Brivaracetam is an analogue of levetiracetam that is Food and Drug Administration-approved for adjunctive treatment of partial-onset seizures in patients 16 years and older. In placebo-controlled trials adjunct brivaracetam demonstrated efficacy in reducing the frequency of seizures. The most commonly reported adverse effects are somnolence, dizziness, and fatigue. Clinical trials have evaluated brivaracetam for safety and efficacy in adjunctive treatment of partial-onset seizures in patients 16 years and older for up to 16 weeks. Brivaracetam's mechanism is similar to that of levetiracetam but with greater receptor binding affinity on synaptic vesicle protein 2A and inhibitory effects on sodium channels. Clinically significant differences between these agents are undetermined. Brivaracetam is available as oral tablets, oral solution, and intravenous solution. The Food and Drug Administration-approved dose is 50 mg twice daily, and titration is not required. Brivaracetam does not need dose adjustment for renal impairment and has minimal drug-drug interactions. Current limitations of brivaracetam include lack of head-to-head trials, limited long-term safety and efficacy data, and cost. Overall, brivaracetam is a viable adjunct therapeutic option for refractory partial-onset seizures in those who have failed conventional therapies.

OnabotulinumtoxinA Injections for the Treatment of Cyclic Vomiting Syndrome.

Cyclic vomiting syndrome (CVS) is a disorder characterized by episodes of nausea and vomiting lasting 1 to 5 days, followed by asymptomatic periods. The etiology and pathophysiology of CVS are unknown, but CVS shares similar characteristics to those of migraine headaches. Tricyclic antidepressants have the most evidence and are generally effective for prophylaxis of further episodes in patients with CVS. Second-line pharmacotherapies typically target specific comorbid symptoms or conditions and may include antiepileptic or antimigraine drugs, benzodiazepines, antispasmodics, proton pump inhibitors, antiemetics, and analgesics. OnabotulinumtoxinA (ONABoNT-A) injections have not been studied in the population with CVS but are regarded as a pharmacotherapeutic option for migraine headaches. We describe a 45-year-old woman with a 5-year history of CVS who had failed previous typical prophylactic migraine and CVS pharmacotherapies and was referred to the neurology clinic for management of both of these conditions. On review, the neurologist noted a correlation of the patient's headaches with her CVS symptoms. ONABoNT-A injections were started at 155 units intramuscularly every 12 weeks for her migraine headaches, which also dramatically improved her CVS. The main adverse effect reported by the patient was numbness and weakness in her left shoulder after the injections, which are symptoms consistent with ONABoNT-A injection use; however, these symptoms typically resolved a few days later. Regarded as a pharmacotherapeutic option for migraine headache prophylaxis, ONABoNT-A injections have demonstrated modest efficacy in preventing migraine headaches. Clinicians should be aware that ONABoNT-A injections may also have a role in the prophylaxis of CVS.

Gabapentin enacarbil for treatment of restless legs syndrome in adults.

OBJECTIVE: To review the pharmacology, pharmacokinetics, clinical efficacy, adverse effects, drug interactions, precautions, dosing recommendations, and patient counseling for gabapentin enacarbil for the treatment of restless legs syndrome (RLS) in adults. DATA SOURCES: A literature search was conducted using the terms gabapentin enacarbil, XP13512/GSK1838262, and restless legs syndrome. MEDLINE, Books@Ovid, Journals@Ovid Full Text, BIOSIS Previews, and EMED databases were the primary search sites (2004-October 2011). All English-based articles and abstracts obtained from the literature searches were reviewed. Additional information was obtained from references cited in the articles. STUDY SELECTION AND DATA EXTRACTION: All gabapentin enacarbil information related to RLS was considered. Study selection included human trials evaluating safety and efficacy of gabapentin enacarbil for the treatment of RLS. DATA SYNTHESIS: Gabapentin enacarbil is a prodrug of gabapentin that is Food and Drug Administration (FDA) approved for the treatment of moderate-to-severe primary RLS in adults. In placebo-controlled trials, gabapentin enacarbil demonstrated efficacy in reducing the symptoms of RLS. Most clinical trials assessed gabapentin enacarbil at dosages greater than the FDA-approved 600-mg dosage. For the approved dose of 600 mg, the most commonly reported adverse effects are somnolence and dizziness. CONCLUSIONS: Clinical trials have evaluated gabapentin enacarbil for safety and efficacy in treating moderate-to-severe RLS symptoms for up to 64 weeks. It offers a pharmacokinetic advantage over gabapentin by having improved absorption and a longer duration of action, but clinically significant differences are yet to be determined. Potential disadvantages of gabapentin enacarbil include cost, concerns of suicide risk and pancreatic cancer, and a lack of data for the FDA-approved 600-mg dosage. Overall, gabapentin enacarbil is a viable therapeutic option for adults with moderate-to-severe RLS for whom more conventional therapies have failed.