Valacyclovir Hydrochloride (Page 3 of 13)
There is no information specific to administration of valacyclovir tablets in patients receiving peritoneal dialysis. The effect of chronic ambulatory peritoneal dialysis (CAPD) and continuous arteriovenous hemofiltration/dialysis (CAVHD) on acyclovir pharmacokinetics has been studied. The removal of acyclovir after CAPD and CAVHD is less pronounced than with hemodialysis, and the pharmacokinetic parameters closely resemble those observed in patients with end-stage renal disease (ESRD) not receiving hemodialysis. Therefore, supplemental doses of valacyclovir tablets should not be required following CAPD or CAVHD.
3 DOSAGE FORMS AND STRENGTHS
Valacyclovir Tablets, USP are available containing 556.2 mg or 1.112 grams of valacyclovir hydrochloride, USP (hydrous), which are equivalent to 500 mg or 1 gram of valacyclovir, on the anhydrous basis, respectively.
- The 500 mg tablets are white, film-coated, oval, unscored tablets with M122 imprinted with black ink on one side of the tablet and plain on the other side of the tablet.
- The 1 gram tablets are white, film-coated, oval tablets with a partial break line on both sides of the tablet and M123 imprinted with black ink on one side of the tablet.
Valacyclovir tablets are contraindicated in patients who have had a demonstrated clinically significant hypersensitivity reaction (e.g., anaphylaxis) to valacyclovir, acyclovir, or any component of the formulation [see Adverse Reactions (6.3)].
5 WARNINGS AND PRECAUTIONS
5.1 Thrombotic Thrombocytopenic Purpura/Hemolytic Uremic Syndrome (TTP/HUS)
TTP/HUS, in some cases resulting in death, has occurred in patients with advanced HIV-1 disease and also in allogeneic bone marrow transplant and renal transplant recipients participating in clinical trials of valacyclovir tablets at doses of 8 grams per day. Treatment with valacyclovir tablets should be stopped immediately if clinical signs, symptoms, and laboratory abnormalities consistent with TTP/HUS occur.
5.2 Acute Renal Failure
Cases of acute renal failure have been reported in:
- Elderly patients with or without reduced renal function. Caution should be exercised when administering valacyclovir tablets to geriatric patients, and dosage reduction is recommended for those with impaired renal function [see Dosage and Administration (2.4), Use in Specific Populations (8.5)].
- Patients with underlying renal disease who received higher-than-recommended doses of valacyclovir tablets for their level of renal function. Dosage reduction is recommended when administering valacyclovir tablets to patients with renal impairment [see Dosage and Administration (2.4), Use in Specific Populations (8.6)].
- Patients receiving other nephrotoxic drugs. Caution should be exercised when administering valacyclovir tablets to patients receiving potentially nephrotoxic drugs.
- Patients without adequate hydration. Precipitation of acyclovir in renal tubules may occur when the solubility (2.5 mg/mL) is exceeded in the intratubular fluid. Adequate hydration should be maintained for all patients.
In the event of acute renal failure and anuria, the patient may benefit from hemodialysis until renal function is restored [see Dosage and Administration (2.4), Adverse Reactions (6.3)].
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 tablets for their level of renal function. Elderly patients are more likely to have central nervous system adverse reactions. Valacyclovir tablets 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 greater than 10% of adult subjects treated with valacyclovir tablets and observed more frequently with valacyclovir tablets compared with placebo are headache, nausea, and abdominal pain. The only adverse reaction reported in greater than 10% of pediatric subjects aged less than 18 years was headache.
6.1 Clinical Trials Experience in Adult Subjects
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 trials for the treatment of cold sores, the adverse reactions reported by subjects receiving valacyclovir tablets 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 (greater than 2 x ULN) were 1.8% for subjects receiving valacyclovir tablets 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.
In a clinical trial for the treatment of initial episodes of genital herpes, the adverse reactions reported by greater than or equal to 5% of subjects receiving valacyclovir tablets 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.
In 3 clinical trials for the episodic treatment of recurrent genital herpes, the adverse reactions reported by greater than or equal to 5% of subjects receiving valacyclovir tablets 500 mg twice daily for 3 days (n = 402), valacyclovir tablets 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.
Suppression of Recurrent Genital Herpes in Immunocompetent Adults
In a clinical trial for the suppression of recurrent genital herpes infections, the adverse reactions reported by subjects receiving valacyclovir tablets 1 gram once daily (n = 269), valacyclovir tablets 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.
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