Viral Skin Infections (PHARM)

Question 1

Types of Herpes viruses that can infect humans

Answer 1

-HSV 1: herpes simplex virus type 1-(cold sore as re-occurance)
-HSV 2: herpes simplex virus type 2
-VZV: varicella zoster virus (chicken pox) -re-occurance (shingles)
-CMV: cytomegalovirus
-HHV-6: human herpes virus 6 (exanthem subitum or roseola infantum)
-HHV-8-human herpes virus 8 (Kaposi’s sarcoma)

Question 2

Pathophysiology of viral infection

Answer 2

-Neurotropic: grows within neurone
-HSV large virus contains double strand DNA
-Latency: viral gene reside inside a cell and express only a few genes, retreat to dorsal root ganglion (antivirals don’t work in latent phase)

Question 3

Diagnostic Criteria of viral lesions

Answer 3

-Eruptions of clustered vesicles on an erythematous base
-Virus distributed on autonomic and sensory nerve enduing-dorsal root ganglion

Question 4

Goals of drug therapy for Viral

Answer 4

-Reduce duration of symptoms
-Suppress the pain

Question 5

Herpes Simplex: HSV-1 and HSV-2

Answer 5

-Mouth-cold sores
-Eczema herpeticum (develops in patients with atopic dermatitis)
-Genital herpes
-HSV encephalitis
-Herpes whitlow caused by herpes simples where you touch a sore or blister of another infected person

Question 6

Topical antivirals MOA

Answer 6

-Inhibits fusion between the human cell plasma membrane and the herpes simplex virus envelope, thereby preventing viral entry into cells and prevent viral replication

-Initiate within 12 hr of consent of prodromal symptoms
-Apply 5 times daily for 10 days

-Acyclovir 5% (Zovirax)cream

Question 7

Systemic Antivirals

Answer 7

-Acyclovir (low bioavailability 5 times a day)
-Famciclovir (bioavailability 5-75%)
-Valacyclovir (BEST to prescribe, BID dosing)

-Inhibits DNA replications, only in HSV infected cells
-Initiate within 72 hours of rash onset to reduce the duration of viral shedding

Question 8

Contraindications antivirals

Answer 8

-Cr clearance lesss than 50 ml/min, needs dose adjustment)