Glaucoma - tafluprost
Glaucoma is a serious disease of the eye that becomes more common with age, and it can all too easily lead to blindness if it is not properly treated.
Glaucoma is a serious disease of the eye that becomes more common with age, and it can all too easily lead to blindness if it is not properly treated.
The most common form, open angle or chronic simple glaucoma, is characterised by a gradual rise in pressure within the eye that is usually painless, and impairment of the patient's vision progresses slowly. The acute or angle closure form develops less often, and results from a sudden closing of the angle between the cornea and the iris. This blocks the drainage of aqueous humour from the eye, leading to a rapid rise in intraocular pressure, and both pain and blurred vision result.
Surgery can be used to drain aqueous humour from the eye, reducing the pressure, but a drug treatment is less invasive. Acetazolamide, for example, blocks the production of aqueous humour, while prostaglandin analogues can be used to improve the flow of intraocular fluid out of the eye. However, side-effects such as headache, irritation and conjunctival hyperemia are common, and a new prostaglandin analogue, tafluprost, is being co-developed by Santen and Asahi Glass in Japan.1
A placebo controlled, ascending dose Phase I trial was carried out in eight Japanese and 16 non-Japanese healthy male subjects to discover an appropriate concentration of tafluprost in glaucoma treatment.2 Subjects were given doses in concentrations of 0.0001, 0.0005, 0.0025 and 0.005% of the drug once on the first day of the trial, and twice on the second. The two higher concentrations had the greatest effect on lowering intraocular pressure, and no serious adverse events were observed.
Two further randomised Phase I trials were carried out in 27 Japanese and 49 non-Japanese healthy volunteers.3 Subjects were given eye drops containing 0.0025 or 0.005% tafluprost, 0.005% latanoprost or placebo once a day for seven days. Significantly greater reductions in intraocular pressure were observed in the non-Japanese subjects given the higher dose of tafluprost than either latanoprost or placebo. In the Japanese group, the higher dose gave a statistically significant decrease, while none of the other doses did. Again, there were no serious adverse events.
A Phase II randomised trial was carried out in 38 patients with open angle glaucoma or ocular hypertension.4 Subjects were given either 0.015% tafluprost or 0.005% latanoprost as eye drops for six weeks. No statistically significant differences in effect were seen between the two dosing arms, and tafluprost caused only a low incidence of mild conjunctival redness. Trials continue, and the drug has been filed in Japan for treating open angle glaucoma.