The stability of valacyclovir hydrochloride in three commonly used syrups w
Triplicate suspensions of valacyclovir (from caplets) in Ora-Sweet (Paddock
Laboratories), Ora-Sweet SF (Paddock), and Syrpalta Humco Laboratory) syru
ps were extemporaneously compounded to yield a final concentration of valac
yclovir 50 mg/mL las the hydrochloride salt). The nine suspensions were sto
red at 4 degrees C in amber glass bottles. At intervals up to 60 days, the
liquids were visually inspected for color change, cloudiness, gas formation
, and precipitation, and samples were assayed in duplicate for valacyclovir
concentration by stability-indicating high-performance liquid chromatograp
hy. Also tested were pH, particle size, and microbial growth.
During the first 21 days of storage, mean valacyclovir concentrations in al
l liquids were >90% of the initial concentration, but concentrations were <
90% by day 21 in some individual samples of suspensions prepared with Ora-S
weet and Ora-Sweet SF. Mean valacyclovir concentrations in the Syrpalta-bas
ed suspensions met the 90% cutoff for at least 35 days. Solution pH and par
ticle size remained unchanged in all liquids through day 60, and there were
no changes in physical appearance. There was no evidence of microbial grow
th on the days when microbial growth was tested (0 and 28).
Valacyclovir 50 mg/mL las the hydrochloride salt) in three oral liquids sto
red in amber glass bottles at 4 degrees C was stable for at least 21 days w
hen prepared with two of three syrups and for at least 35 days when prepare
d with the third syrup. All the liquids were free of microbial growth for a
t least 28 days.