Insufficient numbers of Sino-implant users available for study participation.

A cross-sectional study to compare pharmacokinetics of Sino-implant (II) during four years of used and Jadelle during five years of use by Kenyan women.

A cross-sectional study to compare the pharmacokinetics of Sino-implant (II) during four years of use and Jadelle during five years of use by Kenyan women. The active ingredient in both implants is levonorgestrel (LNG) which is a synthetic progestin that has been used in combined oral contraceptives and in progestin-only pills for more than 30 years.

Population: A total of 280 women between the ages of 18 to 44 years who are currently using Sino-implant (II) or Jadelle contraceptive implants will be enrolled in one of six cohorts of women:

Cohort 1: (n=20 Sino-implant (II), n=20 Jadelle) women enrolled 1-3 months before their 6-month insertion anniversary.

Cohort 2: (n=20 Sino-implant (II), n=20 Jadelle) women enrolled 1-3 months before their 12-month insertion anniversary.

Cohort 3: (n=20 Sino-implant (II), n=20 Jadelle) women enrolled 1-3 months before their 24-month insertion anniversary.

Cohort 4: (n=20 Sino-implant (II), n=20 Jadelle) women enrolled 1-3 months before their 36-month insertion anniversary.

Cohort 5: (n=40 Sino-implant (II), n=40 Jadelle) women enrolled 1-3 months before their 48-month insertion anniversary.

Cohort 6: (n=40 Jadelle) women enrolled 2-6 months before their 60-month insertion anniversary.

Women in all cohorts will be followed for up to 6 months.

Study Duration: Up to 6 months of participant recruitment and up to 6 months elapsed after the baseline visit for the second study visits. 15 months total in the field including training, study initiation, recruitment, follow-up, and close-out.

Two blood samples spaced 2 to 6 months apart will be drawn from each woman for hormone measurements.

Primary Objective: To compare total and free levonorgestrel (LNG) plasma concentrations at four years of Sino-implant (II) use to total and free LNG plasma concentrations at five years of Jadelle use in Kenyan women

Secondary Objectives:

1. To compare total and free LNG plasma concentrations at four years of Sino-implant (II) use to total and free LNG plasma concentrations at four years of Jadelle use
2. To characterize the total and free LNG plasma concentration-time profiles over four years following Sino-implant (II) and over five years following Jadelle insertion
3. To characterize the sex hormone binding globulin (SHBG) serum concentration-time profile over four years following Sino-implant (II) and over five years following Jadelle insertion

Inclusion Criteria:

• Have a Sino-implant (II) or Jadelle implant set in place, confirmed by physical exam;
• Have a confirmed contraceptive implant insertion date consistent with the criteria for the cohort she is to be enrolled in;
• Be aged between 18 and 44 years, inclusive;
• Not wish to become pregnant in the next six months;
• Not desire implant removal within the next six months.
• Be able to understand the information given to them and to make personal decisions on whether to participate or not in the study;
• Consent to participation, and sign an informed consent form;
• Agree and be able to return to the clinic for the second study visit.

Exclusion Criteria: The following criteria exclude participation in the study:

• Use of rifampicin, and/or anticonvulsants (barbiturates, phenytoin, phenobarbital, carbamazepine, oxcarbazepine, primidone, topiramate), and/or herbal products containing St. John's wort (Hypericum perforatum), by self-report;7
• Use of medications containing LNG or other hormones that impact LNG or SHBG disposition, e.g. treatment with LNG or oral contraceptives for bleeding disturbances, by self-report;
• Use of anti-retroviral drugs, by self-report;
• Any condition (social or medical) which in the opinion of the Investigator would make study participation unsafe, would interfere with adherence to study requirements or complicate data interpretation.

Women between the ages of 18 and 44 who have received contraceptive implants from the Marie Stopes Kenya Eastleigh clinic and MSK mobile clinics in the Nairobi area.