Tenofovir Disoproxil Fumarate + Ethinylestradiol/Norgestimate = Unknown or no reaction

Effect on Concentration

Tenofovir Disoproxil Fumarate
No change
Applies within class?
No
Ethinylestradiol/Norgestimate
No change
Applies within class?
No

Pharmacologic Effects

Tenofovir Disoproxil Fumarate
Effect
N/A
Applies within class?
No
Ethinylestradiol/Norgestimate
Effect
N/A
Applies within class?
No

Interaction History

N/A

Last Updated 19-Jul-2018

Summary

Sources

Tenofovir Disoproxil Fumarate vs Ethinyl Estradiol / Norgestimate ^

Study Design

Twenty non-pregnant adult females ages 19 – 34 who were taking a Ethinyl Estradiol / Norgestimate combination oral contraceptive were enrolled in this single-center, thirty-day, open label, fixed sequence, pharmacokinetic drug-drug interaction study. Each woman received norgestimate – ethinyl estradiol alone on study days 1-22, followed by norgestimate – ethinyl estradiol plus tenofovir DF 300 mg once daily for seven days during two consecutive 28-day contraceptive cycles. Pharmacokinetic assessments were performed over 24 hours on days 1 and 29 (corresponding to matching days [day 21] of the two consecutive contraceptive cycles. Serum concentrations of tenofovir DF, norgestimate and ethinyl estradiol were measured

Study Results

Pharmacokinetic parameters of deacetyl norgestimate and ethinyl estradiol were unaltered by coadministration of tenofovir, and tenofovir pharmacokinetic parameters in subjects receiving norgestimate – ethinyl estradiol were consistent with historical control data for tenofovir. Norgestimate (N) Ethinyl Estradiol (EE) Norgestimate / Ethinyl Estradiol alone N / EE plus tenofovir DF % GMR (90% CI) Norgestimate / Ethinyl Estradiol alone N / EE plus tenofovir %GMR (90% CI) AUC 18,700 (4310) 17,800 (4130) 95.1 (91 – 99.4) 1380 (493) 1320 (494) 95.6 (90.7 – 100.6) Cmax 1770 (362) 1680 (446) 94 (87.2 – 101.3) 137 (49.7) 131 (53.4) 93.7 (87.5 – 100.4) Cmin 452 (147) 434 (129) 96.4 (92.4 – 100.5) 27.2 (13.1) 26.1 (11.5) 98.1 (90.8 – 106) Tmax 2.02 (1.02 – 4.02) 2.75 (1-6) NA 2.02 (1 -4.02) 2.75 (1 – 6.01) NA T ½ 18.1 (14.1 – 36.3) 17.5 (12.3 – 30.2) NA 14 (9.41 – 18.5) 13.6 (7.68 – 27.8) NA

Study Conclusions

The authors concluded that there is no clinically significant drug interaction between tenofovir and ethinyl estradiol / norgestimate and that both drugs were well tolerated when they were coadministered. Tenofovir DF is unlikely to affect the pharmacokinetics of hormonal contraceptives.

References

Kearney BP, Mathias A. Lack of effect of tenofovir disoproxil fumarate on pharmacokinetics of hormonal contraceptives. Pharmacotherapy. 2009; 8: 924-929.