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.
However, in women pregnant with twins rather than a singlet, the elimination half-life of OHPC was found to be shorter than this, at 10 days. OHPC has been detected in pregnant women up to 44 days after the last dose. Elimination
OHPC is eliminated 50% in feces and 30% in urine when given by intramuscular injection to pregnant women. Both the free steroid and conjugates are excreted by these routes, with the conjugates more prominent in feces. Veterinary
The pharmacokinetics of OHPC in various ungulates including cattle, buffalo, sheep, and goat have been studied. Time–concentration curves
Chemistry
OHPC, also known as 17α-hydroxyprogesterone caproate or as 17α-hydroxypregn-4-ene-3,20-dione 17α-hexanoate, is a synthetic pregnane steroid and a derivative of progesterone. It is specifically a derivative of 17α-hydroxyprogesterone with a hexanoate (caproate) ester at the C17α position. Analogues of OHPC include other 17α-hydroxyprogesterone derivatives such as algestone acetophenide (dihydroxyprogesterone acetophenide), chlormadinone acetate, cyproterone acetate, hydroxyprogesterone acetate, hydroxyprogesterone heptanoate, medroxyprogesterone acetate, and megestrol acetate, as well as the caproate esters chlormadinone caproate, gestonorone caproate (norhydroxyprogesterone caproate), medroxyprogesterone caproate, megestrol caproate, and methenmadinone caproate. Synthesis
Chemical syntheses of OHPC have been described. : 6

History
Along with hydroxyprogesterone acetate, OHPC was developed by Karl Junkmann of Schering AG in 1953 and was first reported by him in the medical literature in 1954. It was reportedly first marketed in Japan in 1954 or 1955, and was subsequently introduced as Delalutin in the United States in 1956. Due to its much longer duration than parenteral progesterone, OHPC had largely replaced progesterone in clinical practice by 1975.