ACYCLOVIR
Chemistry - An antiviral agent, acyclovir (also known as ACV or acycloguanosine), occurs as a white, crystalline powder. 1.3 mg is soluble in one ml of water. Acyclovir sodium has a solubility of greater than 100 mg/ml in water. However, at a pH of 7.4 at 37°C it is practically all unionized and has a solubility of only 2.5 mg/ml in water. There is 4.2 mEq of sodium in each gram of acyclovir sodium.
When reconstituting acyclovir sodium do not use bacteriostatic water with parabens as precipitation may occur. The manufacturer does not recommend using bacteriostatic water for injection with benzyl alcohol because of the potential toxicity in neonates. After reconstitution with 50-100 ml of a standard electrolyte or dextrose solution, the resulting solution is stable at 25°C for 24 hours. Acyclovir is reportedly incompatible with biologic or colloidial products (e.g., blood products or protein containing solutions). It is also incompatible with dopamine HCl, dobutamine, fludarabine phosphate, foscarnet sodium, meperidine and morphine sulfate. Many other drugs have been shown to be compatible in specific situations. Compatibility is dependent upon factors such as pH, concentration, temperature and diluents used. It is suggested to consult specialized references (e.g., Handbook on Injectable Drugs by Trissel; see bibliography) for more specific information.
Uses, Indications - Acyclovir may be useful in treating herpes infections in a variety of avianspecies and in cats with corneal and/or conjunctival herpes infections. Its use in veterinary medicineis not well established however, and it should be used with caution.
Acyclovir crosses the placenta, but rodent studies have not demonstrated any teratogenic effectsthus far. Acyclovir crosses into maternal milk, but associated adverse effects have not been noted.
Preliminary effects noted in cats, include leukopenia and anemias, that are apparently reversible with discontinuation of therapy.
Overdosage, Acute Toxicity - Oral overdose is unlikely to cause significant toxicity. It is recommended to contact a poison control center for further information should an overdose situation present itself.
Storage, Stability, Compatibility
Acyclovir ointment should be stored in a dry place at room temperature. Acyclovir capsules and tablets should be stored in tight, light resistant containers at room temperature. Acyclovir suspension and sodium sterile powder should be stored at room temperature.When reconstituting acyclovir sodium do not use bacteriostatic water with parabens as precipitation may occur. The manufacturer does not recommend using bacteriostatic water for injection with benzyl alcohol because of the potential toxicity in neonates. After reconstitution with 50-100 ml of a standard electrolyte or dextrose solution, the resulting solution is stable at 25°C for 24 hours. Acyclovir is reportedly incompatible with biologic or colloidial products (e.g., blood products or protein containing solutions). It is also incompatible with dopamine HCl, dobutamine, fludarabine phosphate, foscarnet sodium, meperidine and morphine sulfate. Many other drugs have been shown to be compatible in specific situations. Compatibility is dependent upon factors such as pH, concentration, temperature and diluents used. It is suggested to consult specialized references (e.g., Handbook on Injectable Drugs by Trissel; see bibliography) for more specific information.
Pharmacology - ACYCLOVIR
Acyclovir has antiviral activity against a variety of viruses including herpessimplex (types I and II), cytomegalovirus, Epstein-Barr, and varicella-Zoster. It is preferentiallytaken up by these viruses, converted into the active triphosphate form where it inhibits viral DNAreplication.Uses, Indications - Acyclovir may be useful in treating herpes infections in a variety of avianspecies and in cats with corneal and/or conjunctival herpes infections. Its use in veterinary medicineis not well established however, and it should be used with caution.
Pharmacokinetics - ACYCLOVIR
Acyclovir is poorly absorbed after oral administration (approx. 20%) andabsorption is not significantly affected by the presence of food. It is widely distributed throughoutbody tissues and fluids, including the brain, semen, and CSF. It has low protein binding andcrosses the placenta. Acyclovir is primarily hepatically metabolized and has a half life of about 3hours in humans. Renal disease does not significantly alter half life unless anuria is present.Contraindications, Precautions, Reproductive Safety
Acyclovir is potentially contraindicated(assess risk-benefit) during dehydrated states, pre-existing renal function impairment, hypersensitivity to it or other related antivirals, neurologic deficits, or previous neurologic reactions to othercytotoxic drugs.Acyclovir crosses the placenta, but rodent studies have not demonstrated any teratogenic effectsthus far. Acyclovir crosses into maternal milk, but associated adverse effects have not been noted.
Adverse Effects, Warnings
With parenteral therapy, potential adverse effects include thrombophlebitis, acute renal failure, and ecephalopathologic changes (rare). GI disturbances may occur with either oral or parenteral therapy.Preliminary effects noted in cats, include leukopenia and anemias, that are apparently reversible with discontinuation of therapy.
Overdosage, Acute Toxicity - Oral overdose is unlikely to cause significant toxicity. It is recommended to contact a poison control center for further information should an overdose situation present itself.