When to switch from gabapentin (Neurontin) to Lyrica (pregabalin) for inadequate pain control or intolerable side effects?

From the Guidelines

Switching from gabapentin to pregabalin should be considered when patients experience inadequate pain control despite reaching maximum tolerated gabapentin doses or when they develop intolerable side effects. When deciding to switch, it's crucial to evaluate the patient's current pain control, side effects, and optimize gabapentin dosing first. According to the guidelines for the pharmacological management of neuropathic pain 1, if a patient has inadequate pain relief (e.g., <30% reduction) at target dosage after an adequate trial, switching to an alternative first-line medication is recommended.

Key Considerations for Switching

• Maximum tolerated gabapentin doses are typically 1800-3600 mg daily divided into three doses 1.
• Intolerable side effects with gabapentin, such as excessive sedation, dizziness, or peripheral edema, are also a reason to switch.
• Pregabalin offers advantages over gabapentin, including better bioavailability, a more predictable dose-response relationship, faster onset of action, and twice-daily dosing 1.
• Patients with renal impairment require dose adjustments for both medications.
• The transition should be managed carefully, with pregabalin started at 75 mg twice daily while gradually tapering gabapentin over 1-2 weeks to minimize withdrawal effects.

Pharmacokinetic Differences

• Pregabalin has linear pharmacokinetics, making dosing more straightforward compared to gabapentin's nonlinear pharmacokinetics 1.
• Pregabalin may provide analgesia more quickly than gabapentin because the initial dosage of 150 mg/d has been found to be efficacious in some trials, and the time required to titrate to a full dosage is less 1.

Clinical Decision

The decision to switch from gabapentin to pregabalin should be based on a thorough evaluation of the patient's response to gabapentin, including pain control and side effects, and should consider the potential benefits and risks of the switch, as outlined in the guidelines for neuropathic pain management 1.

From the FDA Drug Label

The efficacy of adjunctive pregabalin in patients taking gabapentin has not been evaluated in controlled trials. Consequently, dosing recommendations for the use of pregabalin with gabapentin cannot be offered.

The FDA drug label does not answer the question.

From the Research

Switching from Gabapentin to Lyrica

When considering switching from gabapentin (Neurontin) to Lyrica (pregabalin) for inadequate pain control or intolerable side effects, several factors should be taken into account.

• Efficacy and Tolerability: Studies have shown that pregabalin can be effective in treating neuropathic pain, with a similar adverse effects profile to gabapentin, including neuropsychological reactions and potential for weight gain and peripheral oedema 2.
• Indications for Switching: Pregabalin may be considered when gabapentin fails to provide adequate pain control or when side effects become intolerable. However, it is essential to note that comparative trials between pregabalin and gabapentin are lacking, making it uncertain whether pregabalin will be effective in patients who have not responded to gabapentin 2.
• Dosing and Transition: Research suggests that transitioning from gabapentin to pregabalin can be done seamlessly and rapidly, with predicted pregabalin-equivalent concentrations comparable to plasma pregabalin concentrations within a short period 3.
• Combination Therapy: There is also evidence to suggest that combining gabapentin and pregabalin may have a synergistic effect in pain control, allowing for reduced doses of individual agents and potentially fewer side effects 4.
• Clinical Considerations: The decision to switch from gabapentin to pregabalin should be based on individual patient response and tolerability, taking into account the potential benefits and risks of each medication 5, 6.

Key Points to Consider

• Pregabalin is a viable option for patients with neuropathic pain who have not responded to gabapentin or have intolerable side effects.
• The transition from gabapentin to pregabalin can be achieved through immediate discontinuation of gabapentin and initiation of pregabalin or a gradual transition with coadministration of both medications.
• Combination therapy with gabapentin and pregabalin may be considered in certain cases, but pharmacokinetics, drug interactions, and adverse reactions must be carefully evaluated.
• Individual patient response and tolerability should guide the decision to switch from gabapentin to pregabalin, with careful consideration of the potential benefits and risks of each medication 2, 5, 4, 6, 3.