Switching between gabapentin and pregabalin for neuropathic pain

Reasons for switching

If neuropathic pain treatment isn’t working or causes side effects, NICE guidance for neuropathic pain in adults advises switching to another option. This may include switching between the gabapentinoids: gabapentin and pregabalin.

Considerations before switching

Before switching, review these key points and check local policy (if available).

Evidence base

There is no national guidance on switching. The evidence is limited to a small number of studies that use varying dose ratios and switching strategies. Most data relate to switching from gabapentin to pregabalin.

Licensing

Pregabalin is licensed for peripheral and central neuropathic pain. Gabapentin is licensed for peripheral neuropathic pain only.

Use of gabapentin for central neuropathic pain is off-label. However, gabapentin is recommended by NICE as a first-line treatment option for adults with all types of neuropathic pain (except trigeminal neuralgia).

Age

Elderly and frail patients are more likely to experience adverse effects. Consider whether switching to an alternate medication may be more appropriate.

Renal function

Gabapentin and pregabalin both require dose adjustment in individuals with reduced renal function.

Consult the summary of product characteristics (SmPC) for gabapentin and pregabalin for further information before determining an equivalent dose and switching strategy.

Respiratory function

Gabapentin and pregabalin both carry respiratory depression warnings. Consider adjusting doses for high-risk patients, including those with neurological disease or prescribed central nervous system depressants and opioids.

Interactions

There are no clinically relevant pharmacokinetic interactions between gabapentin and pregabalin. Additive pharmacodynamic effects may occur if gabapentin and pregabalin are taken concurrently during a switch, as they have a similar mode of action.

High doses

Pregabalin is relatively more dangerous than gabapentin in high doses. Pregabalin blood levels rise proportionally with dose, while gabapentin blood levels do not.

Risk of abuse

Both gabapentin and pregabalin carry the potential for abuse, with warnings strengthened by the MHRA in January 2026. Patient information on the risks of addiction, dependence and withdrawal is available from the MHRA. Consider whether switching to an alternate medication may be more appropriate.

Dose equivalences

The first published study outlining switching from gabapentin to pregabalin used dose equivalences developed by the author. Later studies used a 6:1 ratio of total daily dose of gabapentin to pregabalin. This ratio has become established in local-level NHS guidance.

2021 guidance from the Best Practice Advocacy Centre New Zealand modifies the 6:1 ratio. This is to account for how the two drugs behave differently at increasing doses. If using this guidance to determine a dose equivalence, be aware that it includes doses of gabapentin greater than the maximum UK-licence.

Gabapentin to pregabalin

Using the 6:1 ratio, an equivalent dose of gabapentinoid can be determined using a step-wise approach:

Worked example

A 35-year-old man takes 700mg of gabapentin three times a day for neuropathic pain. Due to a lack of efficacy, a decision is reached to switch to twice-daily pregabalin. Using the step-wise approach, to calculate an appropriate dose of pregabalin:

1. 700mg of gabapentin three times a day gives a total daily dose of 2100mg
2. The 6:1 ratio means that 2100mg of gabapentin is roughly equivalent to 350mg of pregabalin
3. Therefore, with twice-daily dosing, 175mg of pregabalin should be given for each dose
4. Suitable formulations to provide this twice-daily dose are available. There is no need to round up or down. However, consider individual preference and clinical characteristics before prescribing a final dose.

Pregabalin to gabapentin

Using the 6:1 ratio an equivalent dose of gabapentinoid can be determined using a stepwise approach:

Worked example

A 42-year-old woman takes 200mg of pregabalin twice a day for neuropathic pain. Due to intolerable adverse effects, a decision is reached to switch to gabapentin. Using the step-wise approach, to calculate an appropriate dose of gabapentin:

1. 200mg of pregabalin taken twice a day gives a total daily dose of 400mg
2. The 6:1 ratio means that 400mg of pregabalin is roughly equivalent to 2400mg of gabapentin
3. Therefore, with three times daily dosing, 800mg of gabapentin should be given per dose
4. Suitable formulations to provide this dose without rounding up or down are available. However, consider individual preference and clinical characteristics before prescribing a final dose.

Switching strategies

Three different switching strategies are described by the manufacturer or presented in the literature. Decide the best option on a case-by-case basis, taking individual preference and clinical characteristics into account. There is no evidence that any one method is better than another.

Direct switch

This method is described in the literature and has been widely used in local-level NHS guidance.

How to conduct a direct switch

• Prescribe what will be the final dose of the initial medication.
• For the next scheduled dose, substitute with an equivalent dosage of the replacement medication.

Cross-tapering

This method is described in the literature.

How to conduct cross-tapering

• Prescribe half the dosage of the initial medication along with half an equivalent dosage of the replacement medication for two to four days.
• After two to four days, discontinue the initial medication and continue with the replacement drug at full equivalent dosage.

Taper and switch

This method follows the manufacturer’s recommendation. Slow withdrawal is important for individuals with epilepsy to maintain seizure control. However, the importance of slow withdrawal in individuals with neuropathic pain is unknown.

How to conduct a taper and switch

• Prescribe a reducing dosage of the initial medication so that over at least a week the dosage reaches zero.
• For the next scheduled dose, prescribe an initiation dosage of the replacement medication and titrate upwards as directed in the gabapentin or pregabalin SmPC

Monitoring after the switch

Monitor clinical efficacy and adjust dose in response to therapeutic effect, tolerability, and adverse reactions.

Consider referring the individual to NHS patient information on using gabapentin or pregabalin.

Bibliography

Full referencing is available on request.

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