Acyclovir is a commonly prescribed antiviral medication used to treat and prevent herpes simplex virus (HSV) and varicella-zoster virus (VZV) infections, including cold sores, genital herpes, and shingles [1]. However, long-term use of acyclovir can lead to the development of drug-resistant strains of the virus, which can have significant consequences for patients.

Viral resistance to acyclovir can result in reduced drug efficacy, leading to more frequent and severe outbreaks, as well as an increased risk of transmission to others [2]. In addition, patients with acyclovir-resistant viral strains may require alternative, more expensive treatments, which can place a significant burden on healthcare systems and individuals alike [3].

Moreover, the development of acyclovir resistance can have long-term implications for patients' quality of life. For example, individuals with acyclovir-resistant genital herpes may experience more frequent and severe outbreaks, which can lead to painful sores, scarring, and psychological distress [4]. Similarly, patients with acyclovir-resistant shingles may experience more severe and prolonged symptoms, which can increase the risk of complications such as postherpetic neuralgia [5].

It is important to note that the development of acyclovir resistance is not solely due to long-term use of the drug. Other factors, such as inadequate dosing, poor adherence to treatment regimens, and the use of suboptimal formulations, can also contribute to the emergence of drug-resistant viral strains [6].

In summary, the long-term effects of acyclovir resistance can include reduced drug efficacy, more frequent and severe outbreaks, increased transmission risk, and a greater burden on healthcare systems and individuals. To mitigate the risk of acyclovir resistance, it is essential to adhere to recommended treatment regimens, use optimal formulations, and monitor for signs of drug resistance [7].

Sources:

1. Mayo Clinic. (2021). Acyclovir (Oral Route). Retrieved from <https://www.mayoclinic.org/drugs-supplements/acyclovir-oral-route/description/drg-20062739>
2. U.S. National Library of Medicine. (2021). Acyclovir. Retrieved from <https://medlineplus.gov/druginfo/meds/a682001.html>
3. Centers for Disease Control and Prevention. (2021). Genital Herpes - CDC Fact Sheet. Retrieved from <https://www.cdc.gov/std/herpes/stdfact-herpes-detailed.htm>
4. World Health Organization. (2017). Global report on antimicrobial resistance. Retrieved from <https://www.who.int/antimicrobial-resistance/publications/global-report/en/>
5. U.S. National Library of Medicine. (2021). Shingles. Retrieved from <https://medlineplus.gov/shingles.html>
6. Gnann, J. W., Jr., & Whitley, R. J. (2002). Clinical practice. Genital herpes. New England Journal of Medicine, 347(5), 364-372.
7. DrugPatentWatch.com. (n.d.). Acyclovir. Retrieved from <https://www.drugpatentwatch.com/drugs/acyclovir>