Background:

Emtricitabine is a nucleoside reverse transcriptase inhibitor (NRTI) with an EC50 of 0.01 μM in PBMC cell. It is an antiviral drug for the treatment of HIV infection.
Emtricitabine has in vitro activity against both laboratory strains of HIV-1 and HIV-2 and clinical isolates of HIV-1. The 50% effective concentration (EC50) ranges from 0.002 to 1.5 μ mol/L, depending on the viral isolate and cell line used. Emtricitabine demonstrates in vitro synergy with zidovudine and stavudine and additive in vitro activity when combines with zalcitabine or didanosine[1].
Reproductive and developmental toxicology studies are conducted with emtricitabine. Oral doses up to 1000 mg/kg/day provided daily area under the curve (AUC0→24) exposure to pregnant animals approximately 60- (mice) to 120-fold (rabbits) higher than that in humans at the recommended dose of 200 mg given once per day. In a mouse fertility study, emtricitabine had no effect on fertility, sperm count, or early embryonic development. There is no increased incidence of malformations in mouse and rabbit embryofetal toxicology studies. The development and fertility of F1 progeny are unaffected by emtricitabine in a mouse pre- and post-natal study. These data demonstrate a favorable pre-clinical reproductive safety profile for emtricitabine[2].
Reference：
[1]. Saag MS, et al. Emtricitabine, a new antiretroviral agent with activity against HIV and hepatitis B virus. Clin Infect Dis.?2006 Jan 1;42(1):126-31.?
[2]. Xu P, et al. Combined Medication of Antiretroviral Drugs Tenofovir Disoproxil Fumarate, Emtricitabine, and Raltegravir Reduces Neural Progenitor Cell Proliferation In Vivo and In Vitro. J Neuroimmune Pharmacol. 2017 Dec;12(4):682-692.
[3]. Szczech GM, Wang LH, Walsh JP, Reproductive toxicology profile of emtricitabine in mice and rabbits. Reprod Toxicol. 2003 Jan-Feb;17(1):95-108.
[4]. Faltz M, et al. Effect of the Anti-retroviral Drugs Efavirenz, Tenofovir and Emtricitabine on Endothelial Cell Function: Role of PARP. Cardiovasc Toxicol. 2017 Jan 3. [Epub ahead of print]