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Abstract
Levonorgestrel and progesterone plasma levels were measured in women bearing levonorgestrel
subdermal implants. Two groups using four or six levonorgestrel covered rods and one
group of non-hormonal contraceptors were compared. Blood samples were drawn twice
a week for six consecutive weeks at different intervals after treatment administration.
The mean levonorgestrel levels (X ± S.D.) observed in the four rods group was .49
± .13 ng/ml in the first year and decreased to .34 ± .06 in the fifth year of treatment.
The mean values observed in the six rods group were .70 ± .15 ng/ml in the second
year and .43 ± .11 in the sixth year. The levonorgestrel plasma levels were slightly
above those found with NORPLANTR implants in the four rods group and well above it in the six rods group.
The highest plasma progesterone value found in each sampling period was above 9 nmol/l
in 7 (14%) out of 50 subjects in the four rods group, in 2 (4.3%) out of 47 subjects
in the six rods group and in all the 49 control women. In 4 out of the 7 subjects
from the 4 rods group and in the two subjects from the 6 rods group, the highest progesterone
value was preceded and followed by values lower than 6 nmol/l. It was concluded that
the progesterone levels were seldom compatible with the occurrence of ovulation in
women treated with four or six levonorgestrel covered rods which release an estimated
daily dose of 70 and 105 ug, respectively.
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References
Robertson, D.N., Díaz, S., Alvarez Sánchez, F., Holma, P., Mishell, D.R., Coutinho, E., Brache, V., Croxatto, H.B., Faúndes, A., Lacarra, M., Pavez, M., Roy, S., da Silva, A.R., Sivin, I., Stern, J. Contraception with long-acting subdermal implants. A five-year clinical trial with Silastic covered rod implants containing levonorgestrel. In press.
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Sivin, I. Personal communication.
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Article info
Publication history
Accepted:
May 30,
1985
Received:
February 21,
1985
Identification
Copyright
© 1985 Published by Elsevier Inc.
