Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0030193 (pain)
 261,466 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A clear picture of the mechanisms of action of the anti-epileptic agent gabapentin is far from being accomplished. We have analyzed the effects of gabapentin on ligand- and voltage-gated currents in isolated adult rat cortical neurons. Gabapentin failed to modify glutamate currents and produced a slight reduction of GABA responses. Negligible inhibition of sodium, but consistent inhibition of high-voltage-activated calcium conductance was promoted by gabapentin. In addition, gabapentin reduced calcium current sensitivity to dihydropyridine agonist and antagonists. Interestingly, gabapentin also decreased a not-inactivating, cadmium-sensitive, potassium current. These unconventional effects might underlie its efficacy in a variety of diseases which involve periodic discharge patterns as neuropathic pain or essential tremor.
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PMID:The effects of gabapentin on different ligand- and voltage-gated currents in isolated cortical neurons. 1124 35

Gabapentin, which has been approved for add-on therapy of focal seizures, is increasingly used for treatment of neuropathic pain. Its analgesic effect is supposed to be due to reduction of glutamatergic transmission, improvement of GABAergic transmission and to binding to voltage-dependent calcium channels. Experimental studies demonstrated an ameliorating effect of gabapentin on neuropathic pain. Placebo-controlled studies revealed an efficacy of gabapentin against pain in diabetic neuropathy and postherpetic neuralgia and in prophylaxis of migraine. Case reports show an analgesic effect of gabapentin in trigeminus neuralgia and in reflex sympathetic dystrophy. The main adverse events are dizziness, ataxia and somnolence. Controlled studies, which compare the efficacy of gabapentin with that of the respective reference drug, are needed to evaluate its importance in treatment of pain.
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PMID:[Gabapentin therapy for pain]. 1125 57

Calcium channels modulate cell function by controlling Ca(2+) influx. A main component of these proteins is the alpha 2/delta subunit. Nevertheless, how this subunit regulates channel activity in situ is unclear. Gabapentin (GBP), an analgesic and anti-epileptic agent with an unknown mechanism of action, specifically binds to the alpha 2/delta subunit. Using the patch clamp technique, we tested the effects of GBP on Ca(2+) currents from dorsal root ganglion (DRG) cells, the mediators of pain perception, to determine how GBP binding modifies channel activity. In DRGs, GBP significantly reduced whole cell Ca(2+) current amplitude at positive membrane potentials when a pulse preceded the test pulses or when cells were stimulated with a train of pulses. In control cells, neither prepulse depolarization nor pulse trains reduced Ca(2+) currents at positive potentials. GBP did not reduce the low-voltage activated Ca(2+) current under any experimental condition. Similar to DRG cells, GBP attenuated Ca(2+) current in skeletal myotubes at positive membrane potentials in the presence of a depolarizing prepulse. However, GBP did not significantly alter Ca(2+) currents in cardiac myocytes. Reverse transcription-polymerase chain reaction was used to confirm expression of the alpha 2/delta subunit in these cells. Each cell type expressed multiple isoforms of alpha 2/delta. Muscle cells showed a more variable expression of alpha 2/delta subunits than did DRG cells. Our results suggest a possible participation of the alpha 2/delta subunit in the action of GBP. Our data also indicate that GBP inhibits Ca(2+) channels in a use- and voltage-dependent manner at a therapeutically relevant concentration.
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PMID:Differential effect of gabapentin on neuronal and muscle calcium currents. 1130 64

Much progress has been made in the assessment and management of neuropathic pain over the past 5 years. Assessment has improved with the Neuropathic Pain Scale, a new, easily administered, diagnostic tool. Mechanistically, recent studies indicate that peripheral neuropathic pain is generated through a focal inflammatory process rather than axonal destruction. This process also appears to involve mRNA regulation of fast sodium channels, which produce ectopic discharges and are presumably responsible for pain generation. In addition the entire neuraxis undergoes neuroplastic changes as a result of peripheral nerve injury. The available clinical trial data indicate that newer antiepileptic drugs (AEDs), most notably gabapentin, are better alternatives to older medications such as carbamazepine or phenytoin in the treatment of neuropathic pain. Gabapentin is at least as good with respect to actual pain relief as the antidepressants, including amitriptyline, but has a much better safety profile with minimal drug-drug interactions and side effects. Mexiletine is a reasonable alternative agent in patients who have not had a satisfactory response to, or cannot tolerate, the AEDs or antidepressants. Long-acting opioids should be considered in patients refractory to these adjunctive agents. With the advent of the topical lidocaine patch, the first drug with an FDA-approved indication for postherpetic neuralgia, a revolutionary new agent is now available for the treatment of neuropathic pain that does not have any systemic side effects.
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PMID:Advances in the management of neuropathic pain. 1134 17

Failed back surgery syndrome (FBSS) is a long-lasting, often disabling, and relatively frequent (5%-10%) complication of lumbosacral spine surgery. Epidural fibrosis is among the most common causes of FBSS, and it is often recalcitrant to treatment. Repeated surgery for fibrosis has only a 30% to 35% success rate, whereas 15% to 20% of patients report worsening of their symptoms. Long-term outcome studies focusing on pharmacologic management of chronic back pain secondary to epidural fibrosis are lacking in the literature. This report presents 2 cases of severe epidural fibrosis managed successfully with gabapentin monotherapy. In both cases, functional status improved markedly and pain was significantly diminished. Gabapentin has an established, favorable safety profile and has been shown to be effective in various animal models and human studies of chronic neuropathic pain. Clinicians should consider gabapentin as a pharmacologic treatment alternative in the management of FBSS caused by epidural fibrosis.
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PMID:Using gabapentin to treat failed back surgery syndrome caused by epidural fibrosis: A report of 2 cases. 1134 50

Gabapentin (Neurontin) (GBP) is a widely prescribed analgesic used in treating pain patients with peripheral nerve injuries, diabetic neuropathy and cancer. To understand the mechanism of its action, we used the whole-cell patch recording technique to study the effects of GBP on N-methyl-D-aspartate (NMDA)-evoked currents in single dorsal horn neurons isolated from normal rats and from rats with inflammation induced by the injection of complete Freund adjuvant (CFA) to the hindpaw. We found that GBP enhanced NMDA currents in normal neurons only when protein kinase C (PKC) was added to these cells. The enhancement resulted from an increase in the affinity of glycine for NMDA receptors by GBP. In contrast, in neurons isolated from CFA-treated rats, GBP enhanced NMDA responses without any PKC treatment. Since endogenous PKC in inflamed tissue is elevated, these results suggest that GBP exerts its effects only on those cells affected by inflammatory injuries. Thus, the effects of GBP on NMDA receptors are plastic; they depend on the phosphorylation states of cells or receptors. These observations point to a new strategy for drug design. A chemical whose action depends on the state of cells would maximize its effectiveness while keeping its side-effects to a minimum.
Pain 2001 Jul
PMID:Gabapentin actions on N-methyl-D-aspartate receptor channels are protein kinase C-dependent. 1140 42

Gabapentin (GBP) has gained wide acceptance in the treatment of pain, migraine, bipolar illness, and epilepsy. It has a relatively benign side effect profile, lacks significant drug interactions, is not liver metabolized, and is renally excreted. Herein three cases are presented that demonstrate withdrawal symptoms after abrupt discontinuation of GBP. Clinicians are encouraged to taper GBP dosage, especially when patients have taken high doses, and to warn patients of possible adverse effects of abruptly discontinuing GBP themselves.
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PMID:Gabapentin withdrawal syndrome. 1147 99

The objective of this study was to assess the efficacy and safety of Gabapentin as the sole analgesic in patients with HIV-related painful neuropathy. Nineteen patients with HIV-related painful neuropathy were administered Gabapentin. Efficacy was evaluated with two 100-mm Visual Analogue Scales (VAS) (0: no symptom; 100: worst symptom), rating pain and interference of pain with sleep, performed at baseline and monthly intervals. Main Pain VAS score decreased from a baseline of 55.7 +/- 19.1 mm to a final 14.7 +/- 18.6 mm (ANOVA P = 0.0001) and mean Sleep Interference VAS score decreased from a baseline of 60.4 +/- 31.9 mm to a final 15.5 +/- 27.7 mm (ANOVA P = 0.0001). Gabapentin provided significant pain relief in our patients with HIV-associated painful sensory neuropathy.
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PMID:Gabapentin in painful HIV-related neuropathy: a report of 19 patients, preliminary observations. 1150 84

A patient with mycosis fungoides illustrates the problem of pain management during wound care and suggests the utility of a novel treatment, gabapentin. Skin lesions, be they induced through necrosis of tumor, therapy (e.g., radiotherapy), or by pressure ulceration, are often the cause of continuous pain or acute wound dressing pain. Optimizing the analgesic treatment in those patients is thus of major importance. Anti-inflammatory drugs and opioids are the cornerstones in the treatment of cancer pain but are rarely sufficient to control wound pain. Different adjuvant techniques can be used, including topical analgesics, psychological distraction techniques, anxiolytics, and co-analgesics. There is growing evidence that anticonvulsants, and sodium channel blockers in particular, are effective not only in neuropathic but also in inflammatory pain. Gabapentin, a voltage sensitive sodium and calcium channel blocker, was used as a co-analgesic to supplement morphine in this case of cancer wound dressing pain.
J Pain Symptom Manage 2001 Jul
PMID:Gabapentin for pain control in cancer patients' wound dressing care. 1151 5

Prompted by the results of gabaergic drugs, such as valproate and topiramate, we performed this pilot study to assess the effect of gabapentin in cluster headache. Eight patients suffering from episodic cluster headache and four suffering from chronic cluster headache were studied. All of them had failed to respond to traditional prophylactic drugs. The design of the study was an open trial. The main parameter for effectiveness was the number of daily attacks. Gabapentin was given at the daily dosage of 900 mg. All patients were pain free after a maximum of 8 days after starting therapy, with a bout duration thus reduced to 16-40% of the average previous bouts (only applies to episodic cluster patients). We hypothesize that the gabaergic action of gabapentin, perhaps combined with other mechanisms, such as calcium channel blockade, may be responsible for its remarkable effects on cluster headache.
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PMID:Drug-resistant cluster headache responding to gabapentin: a pilot study. 1159 3


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