Discovery of an oral respiratory syncytial virus (RSV) fusion inhibitor (GS-5806) and clinical proof of concept in a human RSV challenge study.

GS-5806 is a novel, orally bioavailable RSV fusion inhibitor discovered following a lead optimization campaign on a screening hit. The oral absorption properties were optimized by converting to the pyrazolo[1,5-a]-pyrimidine heterocycle, while potency, metabolic, and physicochemical properties were optimized by introducing the para-chloro and aminopyrrolidine groups. A mean EC50 = 0.43 nM was found toward a panel of 75 RSV A and B clinical isolates and dose-dependent antiviral efficacy in the cotton rat model of RSV infection. Oral bioavailability in preclinical species ranged from 46 to 100%, with evidence of efficient penetration into lung tissue. In healthy human volunteers experimentally infected with RSV, a potent antiviral effect was observed with a mean 4.2 log10 reduction in peak viral load and a significant reduction in disease severity compared to placebo. In conclusion, a potent, once daily, oral RSV fusion inhibitor with the potential to treat RSV infection in infants and adults is reported.

Pediatric drugs--a review of commercially available oral formulations.

Pediatric oral formulations can be quite scientifically challenging to develop and the prerequisites for both a measurable dosage form to administer based upon bodyweight, and also taste-masking are two of the challenges unique for pediatric oral formulations. The physicochemical and organoleptic properties of the active drug substance such as solubility, chemical stability, and taste along with the intended dose can determine which formulations are feasible to develop. Oral pediatric formulations are available in 17 different varieties and can be either a ready-to-use formulation such as a solution, syrup, suspension, tablet, scored tablet, chewable tablet, orally disintegrating tablet, or thin strip, or can also be a formulation that requires manipulation such as a powder for constitution to a suspension, tablet for constitution to a suspension, powder for constitution to a solution, drops for reconstitution to a suspension, concentrated solution for dilution, effervescent tablet, bulk oral granules, bulk oral powder, or solid in a capsule to mix with food or drink. Recently there has been an increase in pediatric formulation development inspired by increased regulatory incentives. The intent of this review is to educate the reader on the various types of formulations administered orally to pediatrics, the rationale in deciding which type of formulation to develop, the excipients used, development challenges, the in-use handling of oral pediatric formulations, and the regulatory incentives.