Valacyclovir hydrochloride
[CAS# 124832-27-5]

Identification

• Classification: API >> Synthetic anti-infective drugs >> Antiviral drugs
• Name: Valacyclovir hydrochloride
• Synonyms: 9-((2-Hydroxy-ethoxy)methyl)guanine L-valine ester hydrochloride
• Molecular Formula: C₁₃H₂₁ClN₆O₄
• Molecular Weight: 360.80
• CAS Registry Number: 124832-27-5
• EC Number: 641-092-8
• SMILES: CC(C)[C@@H](C(=O)OCCOCN1C=NC2=C1N=C(NC2=O)N)N.Cl

Properties

• Solubility: 14 mg/mL (DMSO), 72 mg/mL (water) (Expl.)

Safety Data

• Hazard Symbols: GHS07 Warning
• Hazard Statements: H302
• Precautionary Statements: P264-P270-P301+P317-P330-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H302
Germ cell mutagenicity	Muta.	2	H341
Reproductive toxicity	Repr.	2	H361
Eye irritation	Eye Irrit.	2	H319
Skin irritation	Skin Irrit.	2	H315
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin corrosion	Skin Corr.	1B	H314
Carcinogenicity	Carc.	2	H351
Eye irritation	Eye Irrit.	2A	H319

Discovory and Applicatios

Valacyclovir hydrochloride is an antiviral medication that is primarily used for the treatment of infections caused by the herpes simplex virus (HSV), varicella-zoster virus (VZV), and cytomegalovirus (CMV). It is the hydrochloride salt form of valacyclovir, an ester prodrug of acyclovir, which undergoes hydrolysis in the body to release acyclovir, its active form.

Valacyclovir was first introduced into clinical practice in the 1990s as a more bioavailable alternative to acyclovir, which, while effective, required frequent dosing due to its limited absorption in the gastrointestinal tract. Valacyclovir, on the other hand, is more readily absorbed after oral administration, providing higher systemic levels of acyclovir and reducing the frequency of dosing. This improvement in pharmacokinetics makes valacyclovir a more convenient treatment option, enhancing patient adherence to prescribed regimens.

The primary application of valacyclovir hydrochloride is in the treatment and prevention of viral infections. It is commonly prescribed for conditions such as genital herpes, shingles (herpes zoster), and cold sores (herpes labialis). Valacyclovir is also used for the prevention of CMV infections in immunocompromised patients, such as those undergoing organ transplants, to reduce the risk of CMV-related complications.

Valacyclovir works by inhibiting viral DNA synthesis. It is phosphorylated by viral thymidine kinase into its active form, acyclovir monophosphate, which is further converted into acyclovir triphosphate by cellular enzymes. Acyclovir triphosphate then competes with deoxyguanosine triphosphate, a nucleotide required for viral DNA replication. By interfering with this process, valacyclovir prevents the replication of the virus, thereby limiting the spread of the infection.

Valacyclovir has been found to be effective in reducing the severity and duration of outbreaks of herpes simplex virus and varicella-zoster virus. It is also beneficial in preventing recurrent episodes of herpes simplex virus in patients with frequent outbreaks. In immunocompromised individuals, valacyclovir has proven effective in preventing CMV infection and reducing the occurrence of CMV disease after organ transplantation.

The drug is generally well-tolerated, though it may cause side effects such as headaches, nausea, abdominal pain, and dizziness. In rare cases, particularly in patients with renal impairment, valacyclovir may lead to more serious side effects like kidney problems or neurological effects. As with all antiviral therapies, it is important that valacyclovir be prescribed and monitored by healthcare professionals to ensure its appropriate use and to mitigate potential risks.

Valacyclovir hydrochloride is typically taken orally, and dosing regimens vary depending on the condition being treated. For example, for herpes simplex virus, the typical dosage is one to two doses per day, whereas for shingles, a higher dose may be required. The effectiveness of the drug is often assessed by the resolution of symptoms, with the drug demonstrating a significant ability to reduce pain, accelerate healing, and decrease viral shedding.

Since its introduction, valacyclovir has become a standard therapy for herpesvirus-related infections. Its success is attributed to its enhanced bioavailability, safety profile, and effectiveness in both treating and preventing viral outbreaks. It continues to be widely used in clinical practice and remains a vital tool in the management of herpesvirus infections.

References

2021. Neurotoxicity associated with acyclovir and valacyclovir: A systematic review of cases. Journal of Clinical Pharmacy and Therapeutics, 46(6).
DOI: 10.1111/jcpt.13464

2020. Efficacy of valacyclovir and famciclovir in herpes zoster: A comparative study. Indian Journal of Pharmacology, 52(6).
DOI: 10.4103/ijp.ijp_555_18

2022. Magnetic properties of binuclear copper(II) complex with antiviral drug valacyclovir hydrochloride. Magnetic Properties of Paramagnetic Compounds, Magnetic Susceptibility Data, Volume 5.
DOI: 10.1007/978-3-662-65098-1_462