Comment
Author: Admin | 2025-04-28
The extent of conversion of valacyclovir to acyclovir is reduced, and the acyclovir half-life is not affected. Dosage modification is not recommended for patients with cirrhosis. HIV Disease: In 9 patients with HIV disease and CD4+ cell counts 3 who received valacyclovir hydrochloride at a dosage of 1 gram 4 times daily for 30 days, the pharmacokinetics of valacyclovir and acyclovir were not different from that observed in healthy volunteers. Geriatrics: After single-dose administration of 1 gram of valacyclovir hydrochloride in healthy geriatric volunteers, the half-life of acyclovir was 3.11 ± 0.51 hours, compared with 2.91 ± 0.63 hours in healthy younger adult volunteers. The pharmacokinetics of acyclovir following single- and multiple-dose oral administration of valacyclovir hydrochloride in geriatric volunteers varied with renal function. Dose reduction may be required in geriatric patients, depending on the underlying renal status of the patient [see Dosage and Administration (2.4), Use in Specific Populations (8.5), (8.6)]. Pediatrics: Acyclovir pharmacokinetics have been evaluated in a total of 98 pediatric patients (1 month to [see Adverse Reactions (6.2), Use in Specific Populations (8.4)]. Acyclovir pharmacokinetic parameter estimates following a 20 mg/kg dose are provided in Table 4. Table 4. Mean (±SD) Plasma Acyclovir Pharmacokinetic Parameter Estimates Following First-Dose Administration of 20 mg/kg Valacyclovir Oral Suspension to Pediatric Patients vs. 1 Gram Single Dose of Valacyclovir Hydrochloride to Adults Parameter Pediatric Patients(20 mg/kg Oral Suspension) Adults1 gram Solid Dose ofValacyclovir Hydrochloridea (N = 15) 1 - 2 - 6 - a Historical estimates using pediatric pharmacokinetic sampling schedule. AUC (mcg•hr/mL)Cmax (mcg/mL) 14.4 (±6.26)4.03 (±1.37) 10.1 (±3.35)3.75 (±1.14) 13.1 (±3.43)4.71 (±1.2) 17.2 (±3.1)4.72 (±1.37) Drug Interactions: When valacyclovir hydrochloride is coadministered with antacids, cimetidine and/or probenicid, digoxin, or thiazide diuretics in patients with normal renal function, the effects are not considered to be of clinical significance (see below). Therefore, when valacyclovir hydrochloride is coadministered with these drugs in patients with normal renal function, no dosage adjustment is recommended. Antacids: The pharmacokinetics of acyclovir after a single dose of valacyclovir hydrochloride (1 gram) were unchanged by coadministration of a single dose of antacids (Al3+ or Mg++). Cimetidine: Acyclovir Cmax and AUC following a single dose of valacyclovir hydrochloride (1 gram) increased by 8% and 32%, respectively, after a single dose of cimetidine (800 mg). Cimetidine Plus Probenecid: Acyclovir Cmax and AUC following a single dose of valacyclovir hydrochloride (1 gram) increased by 30% and 78%, respectively, after a combination
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