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Evaluation of the service provided to neuropathic pain patients treated with gabapentin gel, Gabagel™

Jansen, Valentina, Hiom, Sarah and Khot, Sharmila ORCID: 2020. Evaluation of the service provided to neuropathic pain patients treated with gabapentin gel, Gabagel™. Presented at: British Pain Society Annual Scientific Meeting, Harrogate, England, 10-12 May 2016. British Journal of Pain. , vol.10 (2 (Sup) SAGE Publications (UK and US), p. 62. 10.1177/2049463716639449

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Background Neuropathic pain remains a challenging condition to manage. Gabapentin is a voltage-gated calcium channel blocker which is licensed and commonly administered orally for the management of neuropathic pain. It may however be associated with intolerable side effects in some patient groups which prevents therapeutic doses from being achieved.Topical drug delivery is considered a safer, viable alternative to oral dosing where lower doses can be delivered directly to the site of action. GabaGel(TM) is a topical presentation of gabapentin which has been developed and manufactured as a “Pharmaceutical Special” and subsequently trademarked, in collaboration with St Mary’s Pharmaceutical Unit, a NHS pharmacy manufacturing unit. Patients who present with neuropathic pain which is refractory to conventional therapies, are treated with GabaGel(TM) if deemed clinically appropriate. To assist with future prescribing of this product, a service evaluation was designed to assess efficacy, tolerability, and patient and disease groups who are responders. Aims Our aim was to assess the demographics of patients prescribed GabaGel(TM), including age, indication for GabaGel(TM) and concomitant analgesia used by patients. We also assessed efficacy, tolerability, duration of efficacy, reasons for discontinuation and impact on quality of life measures. Methods Regulatory approval was obtained in the form of service evaluation where no ethics approval was required. Patients attending the pain clinic and treated with GabaGel(TM) (n=148), between 2012 and 2015 were identified through pharmacy records. A postal questionnaire was developed and posted to patients. This included questions on current use of GabaGel(TM), initial and current efficacy, duration of efficacy, concomitant medications and their effects on pain severity, reasons for discontinuation, side effects experienced, and quality of life impact. Patients were sent a letter alongside the questionnaire informing them of the rationale behind the evaluation. They were also informed of planned telephone follow-ups in 3 months’ time for incomplete or non-returned questionnaires. Data from returned completed questionnaires was uploaded on a spreadsheet and analysed using IBM SPSS Statistics Package. Any queries from patients regarding ongoing GabaGel(TM) supply were referred to the Pain Clinic. Results Return rate was 50% (74/148). Indications included general neuropathic pain (GNP) 35.1% (26/74), postherpetic neuralgia (PHN) 14.9% (11/74), trigeminal neuralgia (TGN) 8.1% (6/69), chronic facial pain (CFP) 5.4% (4/74), and complex regional pain syndrome (CRPS) 10.8% (8/74). Pain relief of greater than 30% at one month was seen in CFP 50% (2/4) patients, CRPS 25% (2/8) patients, Peripheral Diabetic Neuropathy (PDPN) 100% (1/1), GNP 34.6% (9/26) patients, PHN 45.5% (5/11), and TGN 33.3% (2/6). Ongoing pain reduction of over 30% was seen in GNP 30.8% (8/26), PHN 45.5% (5/11), and TGN 33.3% (2/6). Of the patients still using GabaGelTM, 73.7% (14/19) continued to experience between 40-100% pain relief. GabaGel(TM) continues to be used by 25.7% (19/74) respondents while 51.4% (38/74) discontinued due to lack of efficacy. Severe nausea was cited as a reason for stopping in 1.4% (1/74), and local irritation in 5.4% (4/74). Conclusion The interim results are encouraging. A mixed response pattern is emerging, possibly attributable to inclusion of patients with a diverse range of pathologies unresponsive to standard medications. Refractory PHN and TGN appear responsive to GabaGel(TM). The overall incidence of systemic and local side effects is low and GabaGel(TM) may be a useful alternative in patients with comorbidities and the elderly. Incomplete questionnaires will be followed up with telephone interview. Patient case notes will also be examined and relevant data pooled to create a responder profile. This survey exposed a lack of a robust mechanism to evaluate unlicensed medications.

Item Type: Conference or Workshop Item (Poster)
Date Type: Published Online
Status: Published
Schools: Pharmacy
Publisher: SAGE Publications (UK and US)
ISSN: 2049-4637
Last Modified: 15 Jun 2023 01:05

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