Allopurinol is a xanthine oxidase inhbitor which has previously been shown to reduce myocardial oxygen consumption in patients with heart failure.  As such, as the authors of this paper decided to investigate the potential benefit of high-dose allopurinol in patients with chronic stable angina.
The double-blinded, randomised, placebo controlled study recruited 65 patients with angiographically documented coronary artery disease, a positive exercise test, and a two month history of stable angina.  Patients were assigned to either 600mg of allopurinol a day or placebo for 6 weeks prior to crossover.  The primary endpoint was time to ST depression, the secondary endpoints were total exercise time and time to chest pain.
Although placebo treatment was also associated with an increase in the median time to ST depression, allopurinol was seen to be more beneficial (249 secs vs. 298 secs; p<0.0002).  In addition, allopurinol increased the median total exercise time to 393secs from a baseline of 301secs, while placebo increased it to 307 secs (p=0.0003).  The time to chest pain was significantly improved by allopurinol to 304secs from a baseline of 234secs (p=0.001, see figure).

Conclusion:

In this small study, Allopurinol treatment acted as a safe anti-ischaemic agent in patients with stable angina.  However, exactly how the drug should be used in combination with other available anti-anginals remains to be clarified.

Figure: Change in time from chest pain to symptoms after treatment with allopurinol or placebo.

• Effect of high-dose allopurinol on exercise in patients with chronic stable angina: a randomised, placebo controlled crossover trial.  Noman A, Ang DSC, Ogston S et al.  Lancet 2010;375:2161-2167.