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  43rd ICAAC Meeting
Chicago, Sept 13-17, 2003
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Tenofovir and Norgestimate/Ethinyl Estradiol: lack of a pharmacokinetic drug interaction
  Kearney et al, Gilead Sciences. ICAAC poster A-1618, Sept 14-17, 2003, Chicago.
The objective of this study was to evaluate the effect of TDF co-administration on the PK and safety of hormonal contraceptive medications. And to evaluate the steady state PK of TDF during administration of TDF in women receiving hormonal contraceptive medications.
HIV-negative female subjects receiving elective oral contraception regimens with a frequently used and representative oral contraceptive medicine containing both estrogenic and progestational components (Ortho tri-cyclen, OTC). This was a 29-day open-label, drug-drug interaction study. All subjects were required to use OTC for 3 consecutive contraceptive cycles and have PK evaluations on the same day od 2 sequential cycles, to ensure a stable dose/regimen and PK profile of contraceptive medications.
24 subjects enrolled: mean age 25 (ranhe 19-26); mean weight 64.1 kg (range 47.7-82.7 kg); race 24 caucasian. 20 subjects were evaluable for PK: 2 subjects discontinued for non-compliance, 2 released when enrollment requirement was satisfied.
TDF PK results were similar to those observed in previous studies in healthy subjects and HIV+ individuals. No serious adverse events were reported in this study. 10 of the 20 (50%) subjects experienced a least 1 treatment-emergent AE. Most common adverse events were headache, mild rash, dysmenorrhea, and nausea. No clinically signifucant changes in lab parameters were observed.
The authors concluded that co-administration of oral contraceptives with TDF did not affect the PK of either the estrogenic or progestational components. TDF PK results when given with oral contraceptives were consistent with previously observed values. Co-administration of oral contraceptives with TDF was generally safe and well tolerated.