Read this topic

Pregabalin and gabapentin matter because, despite names that sound related to GABAThe brain's main calming (inhibitory) chemical messenger, boosted by benzodiazepines and alcohol.Read more → (gamma-aminobutyric acid, the brain's main inhibitory neurotransmitterA chemical messenger that nerve cells release to signal to the next cell.Read more →), they do not act on GABA receptors at all. Both bind the alpha-2-delta subunit of voltage-gated calcium channels, reducing the release of excitatory neurotransmitters from overactive neurons. For example, imagine a patient assuming gabapentin works like a benzodiazepine because both calm anxiety: in fact their mechanisms are completely different, even though the clinical effect can look similar. This distinction matters because it explains why they are used for neuropathic pain (pain from damaged nerves) and generalised anxiety disorder, not for psychosis or seizures alone.

By binding the alpha-2-delta subunit of calcium channels, pregabalin and gabapentin reduce calcium influx into the nerve terminal, which reduces release of excitatory neurotransmittersA chemical messenger that nerve cells release to signal to the next cell.Read more → such as glutamate. This calms overactive nerve signalling, which is why both drugs help neuropathic pain and generalised anxiety disorder (GADGeneralised anxiety disorder, persistent, hard-to-control worry across many areas of life.Read more →), and why gabapentin is also used for some seizure disorders. Picture a patient with both diabetic neuropathy and generalised anxiety disorder: a single drug, pregabalin, can be chosen to treat both problems. In practice, clinicians must still monitor closely, because both drugs carry a real risk of misuse and dependence, and combining either with an opioid dangerously increases the risk of fatal respiratory depression (slowed, inadequate breathing).

• A trainee asks how gabapentin is eliminated from the body. Which description is correct, and what does it imply for prescribing?
• A pharmacologist contrasts how these two gabapentinoids are taken up from the gut. Which difference makes pregabalin's response more predictable at higher doses?
• A man stops high-dose pregabalin abruptly after two years of use. Which cluster of symptoms should he have been warned to expect?
• In which schedule of the Misuse of Drugs Regulations were pregabalin and gabapentin placed when they became controlled drugs in the United Kingdom?

• Benzodiazepines, act directly on GABAThe brain's main calming (inhibitory) chemical messenger, boosted by benzodiazepines and alcohol.Read more → receptors, unlike pregabalin and gabapentin which act on calcium channels instead.
• Opioids, combining with pregabalin or gabapentin dangerously raises the risk of fatal respiratory depression, unlike combining opioids with most other anxiolyticsA drug that reduces anxiety.Read more →.
• Anticonvulsants such as sodium valproate, work mainly through sodium channels or GABAThe brain's main calming (inhibitory) chemical messenger, boosted by benzodiazepines and alcohol.Read more →, whereas gabapentin and pregabalin work through calcium channels.
• SSRISelective serotonin reuptake inhibitor, a common type of antidepressant.Read more → (selective serotonin reuptake inhibitor): first-line for generalised anxiety disorder with low misuse potential, unlike pregabalin which carries dependence risk.

• Biliary excretion is not a meaningful route for this drug.
• The lungs are not an elimination route for this drug.
• The drug undergoes little hepatic metabolism.
• This reverses which of the two shows saturable absorption.
• No high-fat meal requirement applies to this drug.

• Identify the drug, receptor, enzyme or pharmacokinetic change named in the stem.
• Translate it into the immediate mechanism before looking at the options.
• Use timing and the adverse-effect pattern to separate the nearest alternatives.
• Check whether the question asks for mechanism, clinical consequence, monitoring or management.