It is notably not available in Canada, the United Kingdom, New Zealand, or South Africa, and only veterinary formulations are available in Australia. OHPC is also marketed in combination with estradiol valerate as a combined injectable contraceptive in a number of countries including in South America, Mexico, Japan, and China. It has been marketed as an injectable preparation in combination with estradiol benzoate in some countries as well. Price controversy
With the designation of OHPC as an orphan drug by the FDA and approval of Makena in 2011, the price of OHPC in the United States was going to increase from US$15 to US$1,500 for a single dose, or from about US$300 to between US$25,000 and US$30,000 for a typical single month of treatment. This was about a 100-fold increase in cost, with "minimal added clinical benefit", and was a strongly criticized pricing strategy. The FDA subsequently announced that compounding pharmacies could continue to sell OHPC at their usual cost of approximately US$10 to US$20 per dose without fear of legal reprisals. KV Pharmaceutical also opted to reduced its price of Makena to US$690 per dose. OHPC continued to be available at low cost from compounding pharmacies until late 2016, after which time the FDA published new guidance documents prohibiting compounding pharmacies from selling products that are "essentially copies" of commercially available drug products.
The most common one is conjunctival hyperemia, which occurs in more than 10% of patients. Other effects include blurred vision, eye and eyelid redness, eye burning or other discomfort, and permanent darkening of the iris to brown. Occasional adverse effects (in less than 1% of patients) are headache and nausea.Some side effects are specific to the cosmetic formulation, which is applied to the skin at the base of the eyelash rather than instilled into the eye. These include infection if the one-time applicators are reused, and darkening of the eyelid or of the area beneath the eye. Research suggests that wiping the eye with an absorbent pad after the administration of eye drops can result in shorter eyelashes and a lesser chance of hyperpigmentation in the eyelid, compared to not wiping off excess fluid. Interactions
No interaction studies with this substance have been performed. Interactions with systemic (for example, oral) drugs are considered unlikely because bimatoprost does not reach relevant concentrations in the bloodstream. Bimatoprost does not negatively interact with timolol eye drops. Pharmacology
Mechanism of action
Bimatoprost is a structural analog of prostaglandin F2α (PGF2α). Like other PGF2α analogs such as travoprost, latanoprost and tafluprost, it increases the outflow of aqueous fluid from the eye and lowers intraocular pressure. However, in contrast to these it does not act on the prostaglandin F receptor, nor on any other known prostaglandin receptor.