Acyclovir

C. diff Risk

None

Oral Bioavailability

Moderate

Approximate Cost

General Information

Common Usage

Therapy for herpesviral infections (HSV and VZV) including encephalitis.

Prophylaxis of herpesviral infections if recurrent disease or immunocompromised.

Drug Monitoring

Lab

  • Follow SCr as appropriate

  • Check urine for crystals if AKI suspected

  • Ensure adequate hydration for the patient

  • Phlebitis (with IV formulation)

Clinical

  • CNS effects

  • Ensure adequate hydration for the patient

  • Phlebitis (with IV formulation)

Adverse Effects

  •  GI upset

  •  Phlebitis/Extravasation

  •  Increased SCr

  •  AKI from crystal nephropathy
    CNS Effects (confusion, tremor, lethargy, hallucination)

Major Interactions

Mycophenolate can increase the acyclovir concentration

May diminish efficacy of zoster or varicella vaccine

Additional Information

For oral indications, valacyclovir is the pro-drug, which is more bioavailable with more convenient dosing.

Pharmacology

Antimicrobial class: Antiviral. Nucleoside analogue.

Pregnancy category: B

Average serum half life: 3 hours

Urine penetration: Therapeutic

CSF penetration: Therapeutic