Space motion sickness (SMS) commonly experienced by astronauts during a space mission often requires treatment with medication. However, exposure to a microgravity environment results in a myriad of physiological changes that alter bioavailability. In particular, studies indicate that the bioavailability of oral scopolamine (SCOP) is decreased during spaceflight. Although altered gastrointestinal function, including delayed gastric emptying, appears to contribute to decreased bioavailability of oral medications, other factors typical of spaceflight may influence the pharmacokinetics of medications administered via a variety of other non-parenteral routes.
Scopolamine is an effective treatment for motion sickness (MS). The dosage forms of scopolamine most commonly used to prevent motion sickness are oral tablets and transdermal patches. However, the bioavailability of oral medications for MS is often low and highly variable, and effective therapeutic levels from the transdermal patch are reached at a very slow rate. To enhance absorption and potential efficacy of scopolamine therapy, an intranasal formulation of scopolamine (INSCOP) was developed at NASA and an Investigational New Drug (IND) application subsequently filed with the Food and Drug Administration (IND 33,983). Intranasal delivery offers a potential for faster treatment and enhanced efficacy at a reduced dose, thereby minimizing incidence and intensity of untoward side effects.
Despite the proven efficacy of scopolamine for MS treatment, cognitive side effects associated with higher doses of the drug make repeated administration of high doses potentially dangerous in operational settings. Furthermore, oral scopolamine fails to provide protection from MS in 28 to 36% of users due to significant medication loss associated with first-pass metabolism. NASA, in collaboration with the Naval Medical Research Unit – Dayton (NAMRU-D), has been exploring intranasal (IN) formulations of scopolamine for use in military and space operational settings. Although intravenous and intramuscular injections are effective for rescue treatment, they are invasive and therefore, are impractical during spaceflight or dynamic military operations. Alternatively, IN delivery appears promising by avoiding many of the drawbacks of oral and transdermal dosage forms. Additionally, IN delivery is noninvasive and can be self-administered safely without significant side-effects at lower than currently required dose for treatment. The new aqueous spray formulation of INSCOP is specially designed to increase absorption rate and enhance efficacy at a lower dose, thereby making it effective for both rescue and treatment of astronauts and military personnel susceptible to MS. INSCOP will provide NASA and the military with an enhanced and efficacious countermeasure for MS that is very effective, expedient, easy to administer, compatible with all operational settings, and capable of providing options for rescue and prophylactic treatment.
INSCOP aqueous spray features rapid absorption, lower effective dose, short elimination half-life, and a reduction in side effects commonly experienced with oral and transdermal formulations.
This work was done by Lakshmi Putcha of Johnson Space Center. For further information, contact the JSC Technology Transfer Office at (281) 483-3809. MSC-24924