Raltegravir approved in Europe and available in the UK
On 23 January 2008, raltegravir, the first antiretroviral integrase inhibitor manufactured by Merck, was granted European approval.  Results from registrational studies have been previously reported in HTB. [2, 3]
The European license it for use in combination with other active antiretrovirals, in treatment-experienced patients whose current combination is failing to suppress viral load.
Raltegravir is available as 400mg tablets and standard dose is one 400mg table twice daily, with or without food. It is marketed under the trade name Isentress.
The Summary of Product characteristics recommends only using raltegravir with at least one other active ARV. Most guidelines for treating experienced patients recommend using any new drug (including raltegravir) with two new sensitive drugs if these are available. 
Resistance to raltegravir can occur within four weeks, if used as virtual monotherapy, without additional sensitive drugs. 
List price for raltegravir in the UK is approximately £21 a day, although bulk discounted pricing is likely to be available to Trusts.
Nevertheless, the cost may limit access to this important drug for patients who need alternative treatment due to intolerance to current therapy.
A regulatory decision on an indication for first-line therapy based on results from on-going trials in treatment-naive patients is expected to take at least 18 months.
- MSD press release: First in Class Integrase Inhibitor, Isentress (raltegravir), Introduced in the UK. 24 January, 2008.
- Selected reports from HIV Treatment Bulletin include: Raltegravir (MK-0518) Phase 3 trials show successful viral suppression in multi-drug resistant patients
Week 48 raltegravir results in treatment-naive Phase II dose-finding study
Lipid profile of integrase inhibitor MK-0518: 24 week results compared to efavirenz in treatment naIve patients
MK-0518 demonstrates potent efficacy in patients with triple-class resistant virus: 24 week results
- European Summary of Product Charateristics (SPC) for raltegravir
- Integrase inhibitors and resistance. HIV Treatment Bulletin June/July 2007.