Neurontin® (Gabapentin) for Pain
What is Neurontin?
Gabapentin is an anticonvulsant medication with antineuralgic properties. It is indicated for the treatment of epilepsy (repeated seizures), restless leg syndrome, and postherpetic neuralgia. Gabapentin is widely prescribed "off-label" in a number of psychiatric, neurologic, and pain disorders.
The most prominent side effects of Gabapentin include dizziness, drowsiness, fatigue, and peripheral edema (swelling of extremities) 13.
Neuropathic pain (also known as nerve pain) occurs when nerve fibers are injured. Neuropathic pain results from damaged nerves rather than damaged tissue. Neuropathic pain may be also followed by changes in the central nervous system (CNS).
Gabapentin is considered a first-line treatment for different types of nerve pain. Multiple, large, high-quality studies have demonstrated the safety and efficacy of gabapentin in relieving central and peripheral neuropathic pain. It alleviates pain by reducing hyperalgesia and allodynia. Also, gabapentin improves various quality of life measures.
The efficacy of gabapentin in diabetic neuropathy5 and postherpetic neuralgia is similar (though not superior) to tricyclic antidepressants and carbamazepine, but it may be better tolerated. Around 30% of people can expect to achieve more than 50% pain relief.
Dosage for Neuropathic pain:
The initial dose of gabapentin is 100 to 300 mg daily. The dose is gradually increased by 100 - 300 mg every 2-5 days until adequate pain relief or max. 3600 mg/day in 3 divided doses is reached.
To minimize side effects such as sedation and dizziness, the initial dose is often taken at bedtime.
Gabapentin doesn't work immediately and may need to be continued for several weeks before decreased symptoms. Treatment usually require 2 or more months to evaluate its effectiveness in neuropathic pain17.
Sciatica (lumbar radiculopathy) is a persistent pain felt along the sciatic nerve. People usually describe it as pain that starts in the lower back and radiates down one or both legs. The principal source of sciatica is compression of a lumbar nerve root from a herniated disc.
Low back pain is the most common lumbar syndrome. Gabapentin is used to treat low back pain that does not resolve with time and overthe-counter medications. Gabapentin reduces pain and improves back function in patients with low back pain 10.
Gabapentin may diminish chronic back pain caused by epidural fibrosis. There is some evidance that gabapentin 3.
Gabapentin for Post-operative pain
Gabapentin may have a place in the management of postoperative pain 2, 15. It reduces both postoperative pain intensity and opioid requirements. Gabapentin reduces movement-evoked pain and this can lead to enhanced functional postoperative recovery.
High-quality studies have demonstrated opioid-sparing benefit of gabapentin following various surgical procedures. This allows noticeably reduce nausea and vomiting after surgery.
Mechanism of action
Gabapentin is structurally related to GABA (gamma-aminobutyric acid). However, it does not bind to GABAA or GABAB receptors, and it does not appear to influence synthesis or uptake of GABA. High affinity binding sites have been located throughout the brain; these sites correspond to the presence of voltage-gated calcium channels specifically possessing the alpha-2-delta-1 subunit. This channel appears to be located presynaptically, and may modulate the release of excitatory neurotransmitters which participate in epileptogenesis and nociception.
Gabapentin is a water-soluble amino acid originally designed to be a GABA-mimetic analog capable of penetrating the CNS. Surprisingly, it has no direct GABA-mimetic activity. As with pregabalin, the mechanism of action involves drug binding to the α-2-δ subunit of the P/Q-type calcium channels, decreasing their activity. In addition, gabapentin raises brain GABA levels in patients with epilepsy
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