(covers information from several alternate timelines)
Inaprovaline was a synaptic stimulant and cardiostimulant. It worked by fortifying the cell membranes and could be used as a preventative measure or in response to various physical illnesses. Chloromydride was a stronger version of inaprovaline.
In 2151, while exploring an uncharted M-class planet, several of the crew of Enterprise NX-01 became affected by tropolisine. Doctor Phlox discovered that inaprovaline, combined with being removed from the pollen-saturated environment, would allow the delusional effects of tropolisine to dissipate. (ENT: "Strange New World")
Also in 2151, while the crew of the Vahklas was aboard the Enterprise, T'Pol went to bed without meditating. Her dreams were unsettling and she was agitated upon awaking, so she asked Doctor Phlox for 25 milligrams of inaprovaline to calm her nerves. (ENT: "Fusion")
In 2366, the Zalkonian "John Doe" crash landed on a planet and was rescued by the USS Enterprise-D. Suffering from low autonomic responses, Dr. Beverly Crusher gave "John Doe" sixty ccs of inaprovaline. (TNG: "Transfigurations")
When Worf began to lose brain function following his surgery involving the genetronic replicator in 2368, Dr. Crusher injected him with forty ccs of inaprovaline and then seventy-five ccs more. The drug did not have an effect, forcing her to try chloromydride. (TNG: "Ethics")
In 2369, Dr. Crusher administered forty ccs of inaprovaline to 93 year-old Sev Maylor, the mother of Lumerian Ambassador Ves Alkar. It failed to revive the elderly woman (TNG: "Man of the People"), who was pronounced dead in their quarters.
In 2375, The Doctor gave inaprovaline to Seven of Nine after she had been intoxicated by a single glass of champagne. Later that year he administered 2 milligrams of inaprovaline to B'Elanna Torres to counter her cytotoxic shock. (VOY: "Timeless", "Nothing Human")
The same year, The Doctor also gave 20 milligrams of inaprovaline to Captain Kathryn Janeway to cure her of her apparent space sickness. Unbeknownst to them, however, she was actually suffering from the early effects of temporal psychosis. (VOY: "Relativity")
Ensign Lyndsay Ballard was treated by USS Voyager's EMH with an inaprovaline derivative he created to help reverse the effects of genetic alterations performed by the Kobali, who had re-animated her lifeless corpse in accordance with their procreation customs. The injections proved to be ineffective in combating the pathogen responsible for her alteration. Changes from inaprovaline only affected Ensign Ballard's appearance, but not her genetic or physiological makeup. (VOY: "Ashes to Ashes")