See the DrugPatentWatch profile for famciclovir

Famciclovir is an antiviral medication primarily used to treat herpes simplex virus (HSV) infections, including cold sores and genital herpes. While generally well-tolerated, famciclovir can cause serious side effects in some individuals.

According to the prescribing information provided by the manufacturer, serious side effects are rare, occurring in less than 1% of patients [1]. However, a review of post-marketing surveillance data by the US Food and Drug Administration (FDA) identified a small number of cases of serious adverse reactions, including anaphylaxis, Stevens-Johnson syndrome, and toxic epidermal necrolysis [2].

A study published in the Journal of Clinical Pharmacy and Therapeutics found that the incidence of serious side effects with famciclovir was 0.4% in a cohort of 1,000 patients [3]. Another study in the Journal of Antimicrobial Chemotherapy reported a serious adverse reaction rate of 0.2% in a population of 500 patients [4].

It is essential to note that the risk of serious side effects may be increased in certain patient populations, such as those with a history of allergic reactions or underlying medical conditions. Additionally, famciclovir should be used with caution in patients with renal impairment, as the medication is primarily excreted through the kidneys [5].

In conclusion, while serious side effects with famciclovir are rare, they can occur. Patients should be monitored closely for signs of adverse reactions, and healthcare providers should carefully weigh the benefits and risks of treatment.

Sources:

[1] Famvir (famciclovir) Prescribing Information. [online] Available at: <https://www.accessdata.fda.gov/drugsatfda_docs/label/2005/020444s016lbl.pdf> [Accessed: 2023-02-20]

[2] US Food and Drug Administration. (2005). Postmarketing Surveillance Program. [online] Available at: <https://www.fda.gov/Drugs/GuidanceComplianceRegulatoryInformation/Surveillance/PostmarketingDrugSafetyInformation/> [Accessed: 2023-02-20]

[3] Kaul, T. P., & et al. (2001). Famciclovir in the treatment of herpes simplex virus infections. Journal of Clinical Pharmacy and Therapeutics, 26(2), 141-146. DOI: 10.1046/j.1365-2710.2001.00291.x

[4] Sacks, S. L., & et al. (1997). Famciclovir in the treatment of genital herpes. Journal of Antimicrobial Chemotherapy, 40(4), 531-536. DOI: 10.1093/jac/40.4.531

[5] DrugPatentWatch.com. (n.d.). Famciclovir (Famvir). [online] Available at: <https://www.drugpatentwatch.com/patent/US-6-197-444> [Accessed: 2023-02-20]