Jim Smith had severe herpes labialis while he was in college. At that time, the doctor at the student health service prescribed penciclovir cream to decrease the severity and duration of his many cold sores. After 2 weeks of treatment, Mr. Smith's cold sores had mostly healed. However, he developed itching, redness, and blistering around the mouth in the areas where he had applied penciclovir. The drug was discontinued, Mr. Smith was given antihistamines, and the rash healed within a week. Now, at age 28, Mr. Smith has recently changed jobs and moved to a new city following the breakup of a long-term relationship. He has been under great stress at work and has been getting little sleep. He visited his physician because painful eruptions developed on his chest the previous day. His doctor diagnosed acute herpes zoster (shingles) and prescribed oral famciclovir 500 mg every 8 hours
Khare MD and Sharland M. Cytomegalovirus treatment options in immunocompromised patients. Expert Opin Pharmacother 2001;2:1247-1257.
Leung DT and Sacks SL. Current recommendations for the treatment of genital herpes. Drugs 2000;60:1329-1352.
Rajan P and Rivers JK. Varicella zoster virus: Recent advances in management. Can Fam Physician 2001;47:2299-2304.
Sen GC. Viruses and interferons. Annu Rev Microbiol 2001;55:255-281.
for 7 days. Later that day, after beginning his course of treatment, Mr. Smith went to the emergency department complaining of wheezing and an itchy rash over much of his body. His symptoms were consistent with those of a mild anaphylactoid reaction. What happened?
Answer: Famciclovir is a prodrug that is rapidly converted to penciclovir, with a bioavailability of 77%. Maximal plasma concentrations of penciclovir are reached within 45 to 60 minutes of famciclovir administration. Mr. Smith developed an allergy to topical penciclovir when he was treated with this drug during college. This prior contact sensitization to penciclovir allowed him to develop an anaphylactoid reaction following the conversion of oral famciclovir to penciclovir by hepatic first-pass metabolism.
Case Study Picking Up More Than Knowledge in College
Was this article helpful?
Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...