Table 1.

Estimated half-lives in pH 6 uptake buffer, pH 7.4 phosphate buffer, HeLa cell homogenates and Caco-2 cell homogenates (mean ± SEM; n=3).

	Half-lives (min)
	pH 6 buffer	pH 7.4 buffer	HeLa cell homogenates	Caco-2 cell homogenates
3-HPG	stable*	stable*	stable*	stable*
Val-3-HPG (5a)	stable*	493.6 ± 10.4	20.3 ± 0.7	4.8 ± 0.2
Ile-3-HPG (5b)	stable*	704.8 ± 9.7	137.2 ± 3.6	59.6 ± 2.3
Phe-3-HPG (5c)	stable**	261.8 ± 5.0	≪ 5	≪ 1
valacyclovir	stable*	829.4 ± 25.0	142.2 ± 1.2	31.3 ± 0.8

^*no area decrease detected in HPLC after 2 h

^**less than 5% decrease after 2 h