Acyclovir (Zovirax) versus ...
Acyclovir is more effective than erythromycin in reducing the severity and duration of pityriasis rosea.
The study 1 compared the effectiveness of oral erythromycin and oral acyclovir in the treatment of Pityriasis rosea. 42 patients with clinical diagnosis of Pityriasis rosea were enrolled and randomized into two groups. One group was given high-dose oral Acyclovir and another group oral Erythromycin in standard dose. After 8th week, all patients showed complete response in both the groups. The response to oral Acyclovir compared with that to oral Erythromycin was better and was statistically significant in 1st, 2nd, 4th and 6th weeks.
Brivudin (bromovinyl deoxyuridine) is a nucleoside analogue with a high and selective antiviral activity against varicella-zoster virus (VZV) and herpes simplex virus type 1 (HSV-1). Brivudin has a markedly higher anti-VZV potency than oral acyclovir. Brivudin has no nephrotoxic properties, which is an advantage when compared to acyclovir.
In a double-blind survey study2 the incidence of zoster-associated pain occurring or persisting after rash healing was significantly lower in brivudin recipients (32.7%) than in acyclovir recipients (43.5%). Mean duration of postherpetic neuralgia was similar with brivudin (173 days) and acyclovir (164 days).
Acyclovir is a more potent inhibitor of viral DNA polymerase than famciclovir 7. Famciclovir is less potent because it does not cause chain termination of viral DNA. However, famciclovir achieves higher intracellular concentrations for longer periods of time than acyclovir, and as a result has a prolonged antiviral effect.
Famciclovir is more bioavailable than acyclovir (77% versus 30%) and has a longer intracellular half-life which allows for a twice daily dosing. So famciclovir is more convenient because it requires less frequent dosing.
However, high cost of famciclovir may override its convenience when choosing between two medications that have comparable efficacy.
Acyclovir and famciclovir have comparable efficacy and similar safety profile.
In the clinical study there was no significant differences between
the four treatment regiments (famciclovir 750 mg once daily, 500 mg
twice daily and 250 mg daily, and acyclovir 800 mg five times daily)
with respect to times to full crusting; loss of vesicles, ulcers and
crusts; cessation of new lesion formation; a 50% reduction in the
area of affected skin; and the loss of acute pain. 6
Penciclovir has a mechanism of action similar to that of acyclovir. Penciclovir triphosphate acts as a competitive inhibitor of viral DNA polymerase, but unlike acyclovir, it does not cause chain termination.
Herpes labialis (cold sores)
In comparative model the efficacy of penciclovir cream was greater than acyclovir cream. 5
The results of the study showed that there are no significant differences in clinical efficacy between penciclovir 1% cream and acyclovir 3% cream with respect to clinical cure rate, times to healing, resolution of all symptoms, absence of blisters, cessation of new blisters, crusting, and loss of crust. However a significantly shorter time to crusting was found with penciclovir when compared with acyclovir. Adverse experience was comparable with two medications. 4
Published: March 31, 2008