In a pharmacokinetic study comparing flunisolide nasal solution (flunisolide nasal spray .025%) (29 mcg per spray) with flunisolide nasal solution (flunisolide nasal spray .025%) (25 mcg per spray), the original formulation, the two formulations were not bioequivalent. The total absorption of flunisolide nasal solution (29 mcg per spray) was 25% less than that of flunisolide nasal solution (25 mcg per spray), and the peak plasma concentration was 30% lower. The clinical significance of these differences is likely to be small, particularly since clinical efficacy is attributable to a local effect on nasal mucosa (see Pharmacodynamics ).
Decongestant nasal sprays are available over-the-counter in many countries. They work to very quickly open up nasal passages by constricting blood vessels in the lining of the nose. Prolonged use of these types of sprays can damage the delicate mucous membranes in the nose. This causes increased inflammation, an effect known as rhinitis medicamentosa or the rebound effect . Decongestant nasal sprays are advised for short-term use only, preferably 5 to 7 days at maximum. Some doctors advise to use them 3 days at maximum. A recent clinical trial has shown that a corticosteroid nasal spray may be useful in reversing this condition.  Topical nasal decongestants include:
Corticosteroids have been used as drug treatment for some time. Lewis Sarett of Merck & Co. was the first to synthesize cortisone, using a complicated 36-step process that started with deoxycholic acid, which was extracted from ox bile .  The low efficiency of converting deoxycholic acid into cortisone led to a cost of US $200 per gram. Russell Marker , at Syntex , discovered a much cheaper and more convenient starting material, diosgenin from wild Mexican yams . His conversion of diosgenin into progesterone by a four-step process now known as Marker degradation was an important step in mass production of all steroidal hormones, including cortisone and chemicals used in hormonal contraception .  In 1952, . Peterson and . Murray of Upjohn developed a process that used Rhizopus mold to oxidize progesterone into a compound that was readily converted to cortisone.  The ability to cheaply synthesize large quantities of cortisone from the diosgenin in yams resulted in a rapid drop in price to US $6 per gram, falling to $ per gram by 1980. Percy Julian's research also aided progress in the field.  The exact nature of cortisone's anti-inflammatory action remained a mystery for years after, however, until the leukocyte adhesion cascade and the role of phospholipase A2 in the production of prostaglandins and leukotrienes was fully understood in the early 1980s.