Bimatoprost

Some of the views expressed in the following notes on newly approved products should be regarded as preliminary, as there may have been limited published data at the time of publication, and little experience in Australia of their safety or efficacy. However, the Editorial Executive Committee believes that comments made in good faith at an early stage may still be of value. Before new drugs are prescribed, the Committee believes it is important that more detailed information is obtained from the manufacturer's approved product information, a drug information centre or some other appropriate source.

Lumigan (Allergan Australia)

0.3 mg/mL in 3 mL, 5 mL and 10 mL bottles

Approved indication: glaucoma

Australian Medicines Handbook section 11.2.5

Prostaglandin F2a agonists are effective drugs for reducing intra-ocular pressure. Bimatoprost has a similar structure and like the prostaglandin F2a agonists it increases the outflow of aqueous humour (see 'New drugs for glaucoma' Aust Prescr 2002;25:142-6).

Patients instil one drop each evening. Intra-ocular pressure starts to fall after four hours and is lowest after 8-12 hours. The pressure falls by about 8 mmHg and the effect is sustained for at least 24 hours. Little bimatoprost is absorbed into the systemic circulation.

In a three-month comparative study once-daily bimatoprost reduced intra-ocular pressure by a mean of 9.16 mmHg. This was a significantly greater reduction than the 6.74 mmHg seen with twice-daily doses of timolol 0.5%.1

Another study compared bimatoprost with latanoprost for three months. Both drugs reduced intra-ocular pressure, but 53% of the patients taking bimatoprost achieved a target pressure of 17 mmHg or less compared with 43% of the latanoprost group.2

Bimatoprost causes more adverse effects than timolol. There is a higher incidence of conjunctival hyperaemia, itchy eyes and growth of eyelashes. Bimatoprost also causes more hyperaemia than latanoprost. Some patients develop increased iris pigmentation. Approximately 7% of patients stopped taking bimatoprost in the clinical trials because of adverse events.

There have been no specific drug interaction studies of bimatoprost, but it can be used as adjunctive therapy in patients whose intra-ocular pressure is not controlled by topical beta blockers.

Bimatoprost is at least as effective as latanoprost, but may be less well tolerated. Longer-term studies are needed to see if the benefits of bimatoprost are sustained.

References

  1. Brandt JD, Van Denburgh AM, Chen K, Whitcup SM. Comparison of once- or twice-daily bimatoprost with twice-daily timolol in patients with elevated IOP. Ophthalmology 2001;108:1023-32.
  2. Gandolfi S, Simmons ST, Sturm R, Chen K. Three-month comparison of bimatoprost and latanoprost in patients with glaucoma and ocular hypertension. Adv Ther 2001;18:110-21.