Antivirals for herpesviruses: Nursing pharmacology

Herpesviruses are a family of DNA viruses that include herpes simplex virus or HSV types 1 and 2, varicella-zoster virus or VZV, cytomegalovirus or CMV for short, Epstein-Barr virus or EBV, and human herpesvirus or HHV 6, 7, and 8.

Certain herpesvirus infections can be treated with a class of antiviral medications called guanosine analogs, which include medications that end in the suffix -clovir.

The main drugs used to treat herpes infections include valacyclovir, valganciclovir, and famciclovir, which are given orally, as well as acyclovir and ganciclovir, which can also be administered topically or intravenously in addition to orally.

Once administered, guanosine analogs act by inserting into the replicating viral DNA. As a result, viral DNA synthesis is halted, ultimately stopping viral replication.

Now, clients taking guanosine analogs may experience headache and nausea. These medications can also cause a skin rash, pruritus, nephrotoxicity, and hypersensitivity reactions like Stevens-Johnson syndrome and angioedema.

Acyclovir and valacyclovir can cause neurological side effects, including agitation, tremors, confusion, and myoclonus; more rarely, clients can develop hallucinations, and even encephalopathy or seizures.

Acyclovir and valacyclovir can also lead to thrombotic thrombocytopenic purpura, and hemolytic uremic syndrome. Acyclovir can also cause pain or phlebitis at the injection site when given intravenously.

On the other hand, famciclovir can cause menstrual changes and hepatotoxicity. Finally, valganciclovir has boxed warnings for hematologic toxicity, carcinogenesis, impaired fertility, and fetal toxicity.

Now, regarding contraindications, guanosine analogs should be used with caution during pregnancy and breastfeeding, and in clients with neurologic, hepatic, or renal disease.

Acyclovir and valacyclovir should also be used cautiously when there’s an electrolyte imbalance or dehydration.

In addition, acyclovir should not be used in combination with zidovudine, as it increases the level of zidovudine and the risk of neurologic side effects; aminoglycosides combined with acyclovir increase the risk of nephrotoxicity.

Okay, now, when your client with a genital herpes simplex virus infection is prescribed an antiviral medication like acyclovir, first perform a baseline assessment, noting their current symptoms, including lesion location, as well as the presence of pain, itching, or drainage.