Valacyclovir is a type of antiviral medicine used to treat viral infections. It is effective for treating cold sores, genital herpes, and herpes zoster. It does not cure herpes but rather prevents the infection from spreading and treats the symptoms. It's an anti-viral medicine. It is used to cure infections by inhibiting viruses from multiplying in human cells. As a result, virus proliferation is halted, and new viruses are slowly produced, causing the viral infection to clear. The FDA granted approval in 1995.
BRAND NAME:
Valtrex – It contains the active ingredients of valacyclovir. It is available in the form of tablets used to treat viral infections.
MECHANISM OF ACTION:
The mechanism of action of valacyclovir is a prodrug that is converted to acyclovir which is then phosphorylated into acyclovir triphosphate. ACV-TP competes with deoxyguanosine triphosphate for incorporation into viral DNA which blocks viral DNA polymerase activity.
PHARMACOKINETICS:
Absorption: After oral administration of valacyclovir hydrochloride is rapidly absorbed from the gastrointestinal tract and converted into acyclovir and L-valine.
Distribution: The volume of distribution of valacyclovir was 1.34±0.65 L/kg
Metabolism: Valacyclovir is metabolized by the liver, where it is promptly and practically entirely converted to acyclovir and L-valine via the first-pass effect. Acyclovir is hepatically metabolized to a very minor level by aldehyde oxidase, as well as alcohol and aldehyde dehydrogenases.
Excretion: The excretion of valacyclovir is through urine and feces
PHARMACODYNAMICS:
Valacyclovir inhibits Herpes simplex virus types 1 and 2 as well as varicella-zoster virus, Epstein-Barr virus, and cytomegalovirus to variable degrees. Valacyclovir is transformed into acyclovir via intestinal and hepatic metabolism. Competes with deoxyguanosine triphosphate for viral DNA polymerase, inhibiting DNA synthesis and replication.
DOASAGE AND ADMINISTRATION:
Valacyclovir comes in the form of tablets that can be taken orally. It is typically administered every 8 hours for 7 days to treat shingles. Genital herpes is typically treated with twice-daily doses for five days.
Valacyclovir pills are available in two strengths: 500mg and 1 gr.
DRUG INTERACTIONS:
Drug interactions with valacyclovir may include
NSAIDs – ibuprofen, naproxen
Antibiotics – amoxicillin
Anti-allergy medication – cetirizine
Beta-blockers – metoprolol
Vitamin B 12 - cholecalciferol
CONTRAINDICATIONS:
Valacyclovir is contraindicated in patients with known hypersensitivity or intolerance to valacyclovir, acyclovir, or any component of the formulation.
SIDE EFFECTS
Side effects of valacyclovir may include
- Constipation
- Vomiting
- Headache
- Stomach upset
- Diarrhea
- Blood in urine
- Rash
- Itching
- Confusion
- Fever
- Yellowness of the skin
OVERDOSE:
Symptoms of overdose may include
- Constipation
- Dizziness
- Tiredness
- Nausea
- Vomiting
- Headache
- Lack of energy
TOXICITY:
Elderly patients and those with problems with renal function are more likely to experience valacyclovir toxicity, which can occasionally result in central nervous system effects such as encephalopathy, agitation, dysarthria, mania, agitation, encephalopathy, and psychosis, among others. To reduce the risk of toxicity in this population, consider reducing the dose of this drug.
