An initial pharmacokinetic study with a Metered Dose Transdermal Systemfor delivery of the progestogen Nestorone as a possible future contraceptive.
BACKGROUND
Transdermal delivery of steroids is gaining popularity for contraception and hormone replacement therapy. This study aimed to test metered spray delivery of a precise dosage of Nestorone (NES) progestogen as a possible transdermal progestogen-only contraceptive.


METHODS
Six healthy postmenopausal volunteers, not recently using any hormonal therapies, comprise the sample for this study. Each subject was studied on two occasions with multiple blood sampling for assay of NES over a 24-h period: on the first occasion, after a single dosage of 3 x 90 microL NES sprays using a specially devised, precisely metered delivery device; on the second occasion, following the fifth in a series of five daily transdermal dosages of 3 x 90 microL of NES spray. Conventional pharmacokinetic parameters were calculated. NES was assayed in serum using a specific radioimmunoassay.


RESULTS
Mean serum levels of NES peaked at around 20 h following dosing, and levels plateaued at 285-290 pmol/L after 4-5 days of daily spray application. All subjects achieved satisfactory serum levels, although substantial intersubject variation was noted. The apparent elimination half-life of NES after the last dose on Day 5 was 26.8 h. No unexpected adverse events were encountered.


CONCLUSIONS
This early pharmacokinetic trial of a new transdermal steroid delivery system has demonstrated the feasibility of achieving serum levels of NES sufficient to block ovulation and potentially provide effective contraception.
Department of Obstetrics and Gynaecology, University of Sydney, NSW 2006, Australia. helena@med.usyd.edu.au
Ian S
IS
Fraser
Edith
E
Weisberg
Narender
N
Kumar
Sushma
S
Kumar
Andrew J
AJ
Humberstone
Louise
L
McCrossin
Deborah
D
Shaw
Y Y
YY
Tsong
Regine
R
Sitruk-Ware
D000279:Administration, Cutaneous; D003271:Contraceptive Agents, Female / Q000008:administration & dosage / Q000493:pharmacokinetics*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009653:Norprogesterones / Q000008:administration & dosage / Q000493:pharmacokinetics*; D017698:Postmenopause
D003271:Contraceptive Agents, Female; D009653:Norprogesterones; C029167:ST 1435