Valacyclovir (Page 3 of 7)

5.3 Central Nervous System Effects

Central nervous system adverse reactions, including agitation, hallucinations, confusion, delirium, seizures, and encephalopathy, have been reported in both adult and pediatric patients with or without reduced renal function and in patients with underlying renal disease who received higher than recommended doses of valacyclovir hydrochloride for their level of renal function. Elderly patients are more likely to have central nervous system adverse reactions. Valacyclovir hydrochloride should be discontinued if central nervous system adverse reactions occur [see Adverse Reactions (6.3), Use in Specific Populations (8.5, 8.6)].

6 ADVERSE REACTIONS

The following serious adverse reactions are discussed in greater detail in other sections of the labeling:
• Thrombotic Thrombocytopenic Purpura/Hemolytic Uremic Syndrome [see Warnings and Precautions (5.1)].
• Acute Renal Failure [see Warnings and Precautions (5.2)].
• Central Nervous System Effects [see Warnings and Precautions (5.3)]. The most common adverse reactions reported in at least 1 indication by >10% of adult patients treated with valacyclovir hydrochloride and observed more frequently with valacyclovir hydrochloride compared to placebo are headache, nausea, and abdominal pain. The only adverse reaction reported in >10% of pediatric patients <18 years of age was headache.

6.1 Clinical Trials Experience in Adult Patients

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in practice.
Cold Sores (Herpes Labialis): In clinical studies for the treatment of cold sores, the adverse reactions reported by patients receiving valacyclovir hydrochloride 2 grams twice daily (n = 609) or placebo (n = 609) for 1 day, respectively, included headache (14%, 10%) and dizziness (2%, 1%). The frequencies of abnormal ALT (>2 x ULN) were 1.8% for patients receiving valacyclovir hydrochloride compared with 0.8% for placebo. Other laboratory abnormalities (hemoglobin, white blood cells, alkaline phosphatase, and serum creatinine) occurred with similar frequencies in the 2 groups.
Genital Herpes:Initial Episode: In a clinical study for the treatment of initial episodes of genital herpes, the adverse reactions reported by ≥5% of patients receiving valacyclovir hydrochloride 1 gram twice daily for 10 days (n = 318) or oral acyclovir 200 mg 5 times daily for 10 days (n = 318), respectively, included headache (13%, 10%) and nausea (6%, 6%). For the incidence of laboratory abnormalities see Table 2.
Recurrent Episodes: In 3 clinical studies for the episodic treatment of recurrent genital herpes, the adverse reactions reported by ≥5% of patients receiving valacyclovir hydrochloride 500 mg twice daily for 3 days (n = 402), valacyclovir hydrochloride 500 mg twice daily for 5 days (n = 1,136) or placebo (n = 259), respectively, included headache (16%, 11%, 14%) and nausea (5%, 4%, 5%). For the incidence of laboratory abnormalities see Table 2.
Suppressive Therapy: Suppression of Recurrent Genital Herpes in Immunocompetent Adults: In a clinical study for the suppression of recurrent genital herpes infections, the adverse reactions reported by patients receiving valacyclovir hydrochloride 1 gram once daily (n = 269), valacyclovir hydrochloride 500 mg once daily (n = 266), or placebo (n = 134), respectively, included headache (35%, 38%, 34%), nausea (11%, 11%, 8%), abdominal pain (11%, 9%, 6%), dysmenorrhea (8%, 5%, 4%), depression (7%, 5%, 5%), arthralgia (6%, 5%, 4%), vomiting (3%, 3%, 2%), and dizziness (4%, 2%, 1%). For the incidence of laboratory abnormalities see Table 2.
Suppression of Recurrent Genital Herpes in HIV-Infected Patients: In HIV-infected patients, frequently reported adverse reactions for valacyclovir hydrochloride (500 mg twice daily; n = 194, median days on therapy = 172) and placebo (n = 99, median days on therapy = 59), respectively, included headache (13%, 8%), fatigue (8%, 5%), and rash (8%, 1%). Post-randomization laboratory abnormalities that were reported more frequently in valacyclovir subjects versus placebo included elevated alkaline phosphatase (4%, 2%), elevated ALT (14%, 10%), elevated AST (16%, 11%), decreased neutrophil counts (18%, 10%), and decreased platelet counts (3%, 0%), respectively.
Reduction of Transmission: In a clinical study for the reduction of transmission of genital herpes, the adverse reactions reported by patients receiving valacyclovir hydrochloride 500 mg once daily (n = 743) or placebo once daily (n = 741), respectively, included headache (29%, 26%), nasopharyngitis (16%, 15%), and upper respiratory tract infection (9%, 10%).
Herpes Zoster: In 2 clinical studies for the treatment of herpes zoster, the adverse reactions reported by patients receiving valacyclovir hydrochloride 1 gram 3 times daily for 7 to 14 days (n = 967) or placebo (n = 195), respectively, included nausea (15%, 8%), headache (14%, 12%), vomiting (6%, 3%), dizziness (3%, 2%), and abdominal pain (3%, 2%). For the incidence of laboratory abnormalities see Table 2.
Table 2. Incidence (%) of Laboratory Abnormalities in Herpes Zoster and Genital Herpes Study Populations

Laboratory Abnormality Herpes Zoster Genital Herpes Treatment Genital Herpes Suppression
Valacyclovir Hydrochloride 1 gram 3 times daily (n = 967) Placebo (n = 195) Valacyclovir Hydrochloride 1 gram twice daily (n = 1,194) Valacyclovir Hydrochloride 500 mg twice daily (n = 1,159) Placebo (n = 439) Valacyclovir Hydrochloride 1 gram once daily (n = 269) Valacyclovir Hydrochloride 500 mg once daily (n = 266) Placebo (n = 134)
Hemoglobin (<0.8 x LLN) 0.8% 0% 0.3% 0.2% 0% 0% 0.8% 0.8%
White blood cells (<0.75 x LLN) 1.3% 0.6% 0.7% 0.6% 0.2% 0.7% 0.8% 1.5%
Platelet count (<100,000/mm 3) 1.0% 1.2% 0.3% 0.1% 0.7% 0.4% 1.1% 1.5%
AST (SGOT) (>2 x ULN) 1.0% 0% 1.0% a 0.5% 4.1% 3.8% 3.0%
Serum creatinine (>1.5 x ULN) 0.2% 0% 0.7% 0% 0% 0% 0% 0%

a Data were not collected prospectively.

LLN = Lower limit of normal.
ULN = Upper limit of normal.

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