Acyclovir is an antiviral medicine used predominantly in treating conditions like Herpes Simplex and Herpes Zoster. The chemical falls under the name of acycloguanosine and is marketed through trade names like Zovir, Acivir, Herpex, Cyclovir etc. The drug Acyclovir was the precursor to all antiviral treatments, which are available today.
Unlike its predecessors, the Acyclovir has a structure, which resembles a nucleoside only partially. Instead of the ring of sugar, there is a structure resembling open chains. Through selective conversion, the Acyclovir is converted to acyclo GMP. The resultant monophosphate structure is then transformed into a triphosphate structure, also called acyclo-GTP. This substance is extremely good in inhibiting DNA polymerase, which causes viral infections. Compared to cellular polymerase, this medicine has over 100 times inhibitor effect towards viral polymerase. This acyclo-GMP gets streamlined into the viral form of DNA and this causes chain termination.
Since Acyclovir is an antiviral drug, it is most effective against all specimens found as part of the herpesvirus group. Some of the most common viruses that Acyclovir is effective against include Herpes Simplex types I as well as II, Varicella Zoster, Epstein Barr, Cytomegalovirus also called CMV and many others. However, this list is of the viruses, which Acyclovir is most effective against.
Acyclovir is not easily dissolved when placed in water. It is not possible to administer it orally, especially when a high concentration of Acyclovir is mandatory. In situations where oral administration becomes essential Acyclovir needs to be given to the patient through intravenous methods. If it is given orally then peak plasma accumulation can happen within a time span of 1 or 2 hours. Having a high rate of distribution, just 30% of Acyclovir is actually plasma bound. The half life elimination of Acyclovir is around 3 hours in duration. Through a process of glomerular filtration and tubular secretion the Acyclovir is renally eliminated from the body. If oral administration is essential then instead of Acyclovir a substance called Valaciclovir can be administered. This has oral bioavailability amounting to 55%. This substance will subsequently get converted into Acyclovir through esterases through process of first-pass metabolic activity.
Acyclovir is usually administered in tablet forms of 200, 400, 800 mg as well as 1 gm measures. It is also available in the market as a topical cream of 5% concentration, ophthalmic ointment of 3% concentration of Acyclovir, as well as in intravenous injections where the concentration of Acyclovir is around 25 mg per mL. The ointments are typically used to treat Herpes Simplex in the labia. When higher concentrations of Acyclovir are required, then intravenous injections are essential. If the Herpes Simplex occurs as a Keratitis or in the eye then the ophthalmic ointment can be used.
Some of the side effects associated with extended treatment through Acyclovir include diarrhea, nausea and vomiting, headaches. In higher concentrations, patients have reported hallucinations as well. Confusion, sore throat and agitation are some other common side effects associated with Acyclovir.