Use of etonogestrel implant beyond approved duration: prolonged contraceptive effectiveness

Long-acting reversible contraception with etonogestrel implants in female macaques (Macaca mulatta and Macaca fascicularis)

Introduction

Contraception is often required for management and population control purposes in group-housed and free-roaming non-human primates. Long-acting reversible contraceptives, including subdermal progestin-releasing implants, are preferred as they eliminate challenges associated with frequent administration. Etonogestrel (ENG)-releasing subdermal implants are reversible and long-acting for a minimum of 3 years, and are commercially available for human use as Implanon® or Nexplanon®.

Methods

A retrospective analysis was performed detailing the contraceptive effectiveness and reversibility of subdermal placement of one-fourth or one-third of an ENG implant (68 mg/implant) in 129 female rhesus macaques (Macaca mulatta) and 67 cynomolgus macaques (Macaca fascicularis) at the Biomedical Primate Research Centre (Rijswijk, Netherlands). Furthermore, single cross-sectional ENG serum concentrations were measured for 16 rhesus and 10 cynomolgus macaques, and hemoglobin and blood chemistry pre-ENG and at timepoints >0.5, >1.5, and > 2.5 years post-ENG insertion were evaluated for 24 rhesus macaques. Finally, data were obtained using trans-abdominal ultrasound regarding the influence of ENG on uterine volume and endometrial thickness in 14 rhesus and 11 cynomolgus macaques.

Results

As a contraceptive ENG was in 99.80% (CI 93.50-99.99) and 99.95% (CI 99.95-100) effective in rhesus and cynomolgus macaques, respectively. Prolonged ENG durations of implant use in 14 rhesus macaques (range 3.1-5.0 years) and eight cynomolgus macaques (range 3.2-4.0 years) resulted in no unintended pregnancies. A total of 17 female macaques were allowed to breed after ENG removal, and among them, 14 female macaques (82%) had an uneventful delivery. Serum ENG concentrations with a median ENG duration of 1.2 years (range 0.1-6.0 years) and 1.9 years (range 0.6-4.7 years) resulted in median concentrations of 112 pg./mL (range 0-305 pg./mL) and 310 pg./mL (range 183-382 pg./mL) for rhesus and cynomolgus macaques, respectively. ENG had no clinical effect on hemoglobin and blood chemistry parameters nor on the thickness of the endometrial lining or uterus volume.

Conclusion

This study indicates that both one-fourth and one-third of the ENG implants are effective, long-acting, reversible, and safe contraceptive to use in macaques.

Contraceptive subcutaneous device migration: what does an orthopaedic surgeon need to know? A case report and literature review

Subdermal contraceptive implant is approved in more than 60 countries and used by millions of women around the world. Although relatively safe in nature, their implantation and removal may be associated with potential complications, some of which may require surgical intervention. Two types of peripheral neurological complications are reported: complications related to compressive neuropathy caused by device decubitus and complications related to device improper removal. An healthy 35-year-old woman come to our attention for paresthesia from medial side of right elbow to fourth and fifth fingers. Tinel sign was positive on medial side of distal third of right arm, above the elbow, as well. Clinical history of patients revealed a subcutaneous placement of a etonogestrel implant 3 years before. Patients reported disappearing of tactile feeling of subcutaneous contraceptive implant since two months. At clinical examination, implant was not felt in its original subcutaneous place. X-rays control revealed its proximal and deep migration. Surgical exploration for subcutaneous contraceptive implant removal revealed it lying on the ulnar nerve. Patient referred immediate paresthesia disappearing after surgery. At 1 month follow up no motor or sensory alteration were evident. Removal of implants inserted too deeply must be carefully performed to prevent damages to nervous and vascular structures and it should be performed by operators who are very familiar with the anatomy of the arm. In case of chronic neuropathy caused by implant nerve compression only an appropriate patients information about rare but possible neuropathic symptoms related to device migration and a careful medical history collecting can avoid a mistaken diagnosis of canalicular syndrome.

HORMONAL THERAPY IN WOMEN OF REPRODUCTIVE AGE WITH ENDOMETRIOSIS: AN UPDATE

Medical therapy of endometriosis is under continuous reevaluation. Hereby we updated the drugs currently available or under investigation for the hormonal treatment of endometriosis.