ACYCLOVIR used, dose, Side effects & more

 ACYCLOVIR

BRAND NAME:- ZOVIRAX 200mg tab,250mg /vial for i.v inj ; CYCLOVIR 200mg tab , 5% skin cream; HEPREX 200mg tab, 3% eye oint, 5% skin cream; OCUVIR 200,400,800mg tab,3% eye oint,ACIVIR DT 200,400,800mg tab . ACIVIR EYE 3%oint.

ACYCLOVIR the deoxiguanosine analogue antiviral drug requires a virus specific enzyme for conversion to the active metabolite that inhibits DNA synthesis and viral replication.

 ACYCLOVIR is preferentially taken up the virus infected cells. Because of selective generation of the active inhibitors in the virus infected cells and it's greater inhibitory effects on viral DNA synthesis, ACYCLOVIR has low toxicity for host cells : a several hundred -fold chemotherapeutic index has been noted.

ACYCLOVIR is active only against herpes group of viruses; HSV-1 is most sensitive followed by HSV-2 >VZV =EBV, while CMV is practically not affected. HSV and VZV have been found to develop resistance to acyclovir during therapy;the former primarily due to mutants deficient in the thymidine kinase activity and the latter primarily by change in specificity of virus directed enzyme so that it's affinity for acyclovir is decreased.

Pharmacodynamic:-

Acyclovir is a nucleoside analog that inhibits the action of viral DNA polymerase and DNA replication of different herpesvirus . Acyclovir has a wide therapeutic window as overdose is rare in otherwise healthy patients.

 Mechanism of action:- 

Acyclovir is becomes acyclovir monophosphate due to the action of viral thymidine kinase. Acyclovir monophosphate is converted to the diphosphate form by guanylate kinase. Acyclovir diphosphate is converted to acyclovir triphosphate by nucleoside diphosphate kinase, pyruvate kinase, creatine kinase, phosphoglycerate kinase, succinyl-CoA synthetase, phosphoenolpyruvate carboxykinase and adenylosuccinate synthetase.Acyclovir triphosphate has higher affinity for viral DNA polymerase than cellular DNA polymerase and incorporates into the DNA where the missing 2' and 3' carbons causes DNA chain termination. In other cases acyclovir triphosphate competes so strongly for viral DNA polymerase that other bases cannot associate with the enzyme, inactivating it.

USE:-

ACYCLOVIR is effective in patients with normal as well as deficient immune status.

  Use in treatment of herpes virus.

1.(Genital herpes simplex

 2. Mucocutaneous H. Simplex

 3.H.simplex encephalitis (type-1virus)

4.H. simplex (type 1) keratitis

5. Herpes zoster 

6. Chickenpox 

SIDE EFFECTS:- 

Topical:- stinging and burning  sensation after each application.

Oral :-The drugs is well tolerated; headache, nausea,malaise and some CNS effect are reported.

Intravenous:- Rashes, sweating,emesis and fall in BP occur only in few patients.

Dose :-

Dependents Decreases in g.f.r is the most important toxicity; occurs especially in those with kidney disease; normalises on discontinuation of the drug.

Reversible neurological manifestation (tremors, lethargy, disorientation, hallucinations, convulsions and coma) hase been ascribed to higer doses.

NO TERATOGENIC POTENTIAL HAS BEEN NOTED.

DOSE:- DIRECT BY PHYSICIAN