Asking the wrong questions: another elephant in the room?
I am entering into this discussion about Lyrica and the second use patent on neuropathic pain as I am surprised at the nature of some assertions made, as well as the lack of evaluation of drug prescribing behaviour (an apparent irony I am aware of given my public stance on other issues but not in my view contradictory)
Firstly it is important to establish that current definition of neuropathic pain does include radicular pain of which sciatica is considered as a subtype of. However I do agree with some readers that the mainstay of treatment of acute sciatica should be supportive non-pharmaceutical measures facilitated by limited and short-term use of analgesics and NSAIDs to aid mobilisation. Chronic recalcitrant sciatica may be managed pharmacologically with various neuromodulating agents such as antidepressants and antiepileptics.
Many guidelines in UK and Australia, including government-funded organisations such as the Australian NPS MedicineWise recommend the use of TCA (Tricyclics Antidepressants) such as amitriptyline for use as first line drugs, and gabapentin (and later pregabalin) for those cases refractory to 'standard' treatment. In UK duloxetine, carbamazepine and other drugs are also recommended, some as first line.
However the Australian PBAC (Pharmaceutical Benefits Advisory Committee) inadvertently assisted the rapid uptake of pregabalin to manage neuropathic pain, since pregabalin is the only approved drug for use under the General PBS subsidy program albeit the "refractory" clause (Gabapentin is only subsidised under Repatriation PBS or RPBS). TCAs, duloxetine, and carbamazepine remained unsubsidied ie not covered by PBS for use for neuropathic pain. While some drugs are actually cheap less than AUD 7 for a pack of amitriptyline 50mg X 50, the perception (and the lack of subsidiy safety net coverage) of the cost/efficacy/side-effect profile of basic drugs like amitriptyline means that there is less apparent economic and time incentive for prescribers to trial first line drugs before prescribing pregabalin. A different problem in which recommendation of these drugs for use in neuropathic pain being unlicenced/off label appears to exist in UK (ref 1 Box 2).
Furthermore Lyrica has been heavily promoted by Pifzer in Australia since its approval for PBS subsidies; the effect of which that I have seen surprising number of patients with back pain without radiculopathy on Lyrica initiated by GPs, as well as postoperative orthopaedic patients with no apparent neuropathic pain, placed on Lyrica by Acute Pain Services in various tertiary hospitals in Australia. I suspect this is to some extent the effect of big pharma advertising and prescriber (mis-) understanding of the definition of neuropathic pain.
The number of patients being started on Lyrica is at least 39% more than expected in the first year of approval by the PBAC in Australia, though it is unclear if it represent a consistent trend (ref 2)
There is no good evidence I am aware of showing pregabalin is any more effective than gabapentin or amitriptyline. I am happy to be corrected in this.
Perhaps its time to go back to look at the good old cheap and dirty rather than the new bright and shiny?
1. Kalso E, Aldington DJ. Drugs for neuropathic pain. BMJ 2013;347:f7339 doi: 10.1136/bmj.f7339
2. Drug utilisation sub-committee (DUSC), PBAC, Department of Health, Australian Government. Pregabalin: 12 month predicted versus actual analysis. October 2014. http://www.pbs.gov.au/industry/listing/participants/public-release-docs/...
Competing interests: I have previously written about my concerns regarding the surprising number of patients on pregabalin with no obvious pain neuropathic in nature