## Gabapentinoid Mechanism in Neuropathic Pain **Key Point:** Gabapentinoids (pregabalin and gabapentin) bind to the α2δ subunit of voltage-gated calcium channels (VGCCs), reducing calcium influx and subsequent neurotransmitter release from hyperexcitable neurons. ### Mechanism of Action 1. **Binding site:** α2δ-1 and α2δ-2 subunits of presynaptic L-type and N-type VGCCs 2. **Effect:** Decreased calcium entry → reduced release of excitatory neurotransmitters (glutamate, substance P, noradrenaline) 3. **Result:** Reduced neuronal hyperexcitability characteristic of neuropathic pain states ### Distinction from Other Analgesics | Drug Class | Mechanism | Primary Use | |-----------|-----------|-------------| | Gabapentinoids | α2δ VGCC binding | Neuropathic pain, postherpetic neuralgia, diabetic neuropathy | | Tricyclic antidepressants | Monoamine reuptake inhibition | Neuropathic pain, chronic pain | | NMDA antagonists | Receptor blockade | Chronic pain, complex regional pain syndrome | | SNRIs | Serotonin/noradrenaline reuptake inhibition | Neuropathic pain, depression | **High-Yield:** Pregabalin is more potent and has better bioavailability than gabapentin, making it the preferred gabapentinoid for neuropathic pain. Both are FDA-approved for postherpetic neuralgia and diabetic peripheral neuropathy. **Mnemonic:** **VGCC** = **V**oltage-**G**ated **C**alcium **C**hannel. Gabapentinoids bind the α2δ subunit to reduce calcium influx and pain signaling. **Clinical Pearl:** Gabapentinoids are particularly effective in neuropathic pain because they address the underlying mechanism of neuronal hyperexcitability rather than simply blocking pain transmission like NSAIDs or opioids. 
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