Aciclovir is a weak CYP1A2 inhibitors. When aciclovir is administered concomitantly with theophylline, toxicosis of theophylline could occur.
The level of aciclovir may be increased by foscarnet, mycophenolate, and tenofovir.
Aciclovir may increase the level of clozapine, mycophenolate, tenofovir, tizanidine, and zidovudine.
Coadministration of zidovudine with aciclovir has been shown the neurotoxicity. Coadministration of probenecid with aciclovir has been shown to increase the mean aciclovir half-life and the area under the concentration-time curve. Urinary excretion and renal clearance were correspondingly reduced.
IV aciclovir should be used with caution in patients receiving interferon. The drugs have an additive or synergistic antiviral effect.