Canterbury DHB

Pregabalin Information Sheet

• Pregabalin comes as capsules: 25 mg, 75 mg, 150 mg, 300 mg (other sizes are approved in NZ but not funded).
• Cost is 10 to 26 cents per day versus 12 to 48 cents for gabapentin.
• Special Authority is not required for pregabalin and is no longer in place for gabapentin formulations.
• Significant abuse of pregabalin has been reported in the US, UK, and Europe.

Indications

• Neuropathic pain – evidence of efficacy is poor and no better than other agents. Have a low threshold for ceasing if ADRs occur.
• Shown to be ineffective in cancer-related bone pain (as has gabapentin).
• Focal seizures – dose as below but 1^st increase after 7 days.
• Generalised anxiety (unapproved)

Dosing recommendations

Doses in normal renal function range from 150 to 600 mg per day. As for most medicines, consider lowest doses in frail or elderly patients.

• Neuropathic pain – initially 75 mg PO BD (some centres start on 25 mg BD) increasing after 3 to 7 days to 150 mg PO BD and again after 7 days to 300 mg PO BD if necessary.
• Generalised anxiety – dose 150 mg/day in 2 to 3 doses increasing by 150 mg/day at 7 day intervals to a maximum of 600 mg/day in 2 to 3 divided doses.

Gabapentin:

• Do not use in combination with gabapentin.
• If switching from gabapentin to pregabalin the conversion ratio is unclear, but consider using a 6:1 gabapentin:pregabalin or retitrate as above.

Clearance and half-life

Pregabalin is cleared renally (like gabapentin) with 90% excreted unchanged so dose adjustments are required for renal function:

• On ceasing it is recommended to withdraw slowly over 7 days (may not be necessary at very low doses).
• Absorption (90%) is better than gabapentin's (25–70%), making for more predictable effects and perhaps useful in gut dysfunction.
• Time to maximum concentrations post dose is 1 hour.
• Half-life is 6 to 12 hours, steady state in 2 to 4 days.
• Mechanism of action is similar to gabapentin and may be through effects on calcium channels in CNS and reduction of glutamate, noradrenaline, and substance P release.

Adverse drug reactions (ADR)

1 in 3 patients will be harmed by pregabalin (but this may be less than gabapentin).

It has many ADRs, including:

• somnolence
• cognitive impairment
• dry mouth
• constipation
• dizziness
• suicidal ideation
• QTc prolongation

Topic Code: 526948