Plasma levels of levonorgestrel in women during longterm use of Norplant

H. B. Croxatto, S. Díaz, P. Miranda, K. Elamsson, E. D.B. Johansson

Resultado de la investigación: Article

32 Citas (Scopus)

Resumen

Levonorgestrel plasma levels were determined by a specific radioimmunoassay in a group of 110 women at various intervals between 1 and 60 months fallowing implantation of six silastic capsules containing levonorgestrel (Norplant). The implants were placed subdermally in the volar aspect of the forearm. Blood samples were taken twice a week for six consecutive weeks in each subject. Blood drawn from the antecubital vein ipsilateral to the implant site contained two to three times more levonorgestrel than contralateral samples. Average systemic plasma levels represented by contralateral samples ranged from 0.35 ± 0.03 to 0.29 ± 0.02 ng/ml (Mean ± S.E.) in the first and fifth year, respectively. The difference between these values is statistically significant at the 5% level. The results of the regression analysis of individual levels suggest that the decline observed throughout the first five years is mainly due to an early decrease taking place in the first two years. When the sampling period was repeated in the same subjects two or three times 10 to 24 months apart, no significant difference was found. A significant negative correlation was found between plasma levonorgestrel levels and body weight and body surface. The data indicate that the contraceptive efficacy of Norplant during the first five years of use is associated with sustained release of levonorgestrel and is in keeping with the estimated life span of Norplant of seven years.

Idioma originalEnglish
Páginas (desde-hasta)197-209
Número de páginas13
PublicaciónContraception
Volumen23
N.º2
EstadoPublished - 1 feb 1981

Huella dactilar

Levonorgestrel
Contraceptive Agents
Forearm
Capsules
Radioimmunoassay
Veins
Body Weight
Regression Analysis

ASJC Scopus subject areas

  • Reproductive Medicine
  • Obstetrics and Gynaecology

Citar esto

Croxatto, H. B., Díaz, S., Miranda, P., Elamsson, K., & Johansson, E. D. B. (1981). Plasma levels of levonorgestrel in women during longterm use of Norplant. Contraception, 23(2), 197-209.
Croxatto, H. B. ; Díaz, S. ; Miranda, P. ; Elamsson, K. ; Johansson, E. D.B. / Plasma levels of levonorgestrel in women during longterm use of Norplant. En: Contraception. 1981 ; Vol. 23, N.º 2. pp. 197-209.
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abstract = "Levonorgestrel plasma levels were determined by a specific radioimmunoassay in a group of 110 women at various intervals between 1 and 60 months fallowing implantation of six silastic capsules containing levonorgestrel (Norplant). The implants were placed subdermally in the volar aspect of the forearm. Blood samples were taken twice a week for six consecutive weeks in each subject. Blood drawn from the antecubital vein ipsilateral to the implant site contained two to three times more levonorgestrel than contralateral samples. Average systemic plasma levels represented by contralateral samples ranged from 0.35 ± 0.03 to 0.29 ± 0.02 ng/ml (Mean ± S.E.) in the first and fifth year, respectively. The difference between these values is statistically significant at the 5{\%} level. The results of the regression analysis of individual levels suggest that the decline observed throughout the first five years is mainly due to an early decrease taking place in the first two years. When the sampling period was repeated in the same subjects two or three times 10 to 24 months apart, no significant difference was found. A significant negative correlation was found between plasma levonorgestrel levels and body weight and body surface. The data indicate that the contraceptive efficacy of Norplant during the first five years of use is associated with sustained release of levonorgestrel and is in keeping with the estimated life span of Norplant of seven years.",
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Croxatto, HB, Díaz, S, Miranda, P, Elamsson, K & Johansson, EDB 1981, 'Plasma levels of levonorgestrel in women during longterm use of Norplant', Contraception, vol. 23, n.º 2, pp. 197-209.

Plasma levels of levonorgestrel in women during longterm use of Norplant. / Croxatto, H. B.; Díaz, S.; Miranda, P.; Elamsson, K.; Johansson, E. D.B.

En: Contraception, Vol. 23, N.º 2, 01.02.1981, p. 197-209.

Resultado de la investigación: Article

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AU - Díaz, S.

AU - Miranda, P.

AU - Elamsson, K.

AU - Johansson, E. D.B.

PY - 1981/2/1

Y1 - 1981/2/1

N2 - Levonorgestrel plasma levels were determined by a specific radioimmunoassay in a group of 110 women at various intervals between 1 and 60 months fallowing implantation of six silastic capsules containing levonorgestrel (Norplant). The implants were placed subdermally in the volar aspect of the forearm. Blood samples were taken twice a week for six consecutive weeks in each subject. Blood drawn from the antecubital vein ipsilateral to the implant site contained two to three times more levonorgestrel than contralateral samples. Average systemic plasma levels represented by contralateral samples ranged from 0.35 ± 0.03 to 0.29 ± 0.02 ng/ml (Mean ± S.E.) in the first and fifth year, respectively. The difference between these values is statistically significant at the 5% level. The results of the regression analysis of individual levels suggest that the decline observed throughout the first five years is mainly due to an early decrease taking place in the first two years. When the sampling period was repeated in the same subjects two or three times 10 to 24 months apart, no significant difference was found. A significant negative correlation was found between plasma levonorgestrel levels and body weight and body surface. The data indicate that the contraceptive efficacy of Norplant during the first five years of use is associated with sustained release of levonorgestrel and is in keeping with the estimated life span of Norplant of seven years.

AB - Levonorgestrel plasma levels were determined by a specific radioimmunoassay in a group of 110 women at various intervals between 1 and 60 months fallowing implantation of six silastic capsules containing levonorgestrel (Norplant). The implants were placed subdermally in the volar aspect of the forearm. Blood samples were taken twice a week for six consecutive weeks in each subject. Blood drawn from the antecubital vein ipsilateral to the implant site contained two to three times more levonorgestrel than contralateral samples. Average systemic plasma levels represented by contralateral samples ranged from 0.35 ± 0.03 to 0.29 ± 0.02 ng/ml (Mean ± S.E.) in the first and fifth year, respectively. The difference between these values is statistically significant at the 5% level. The results of the regression analysis of individual levels suggest that the decline observed throughout the first five years is mainly due to an early decrease taking place in the first two years. When the sampling period was repeated in the same subjects two or three times 10 to 24 months apart, no significant difference was found. A significant negative correlation was found between plasma levonorgestrel levels and body weight and body surface. The data indicate that the contraceptive efficacy of Norplant during the first five years of use is associated with sustained release of levonorgestrel and is in keeping with the estimated life span of Norplant of seven years.

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Croxatto HB, Díaz S, Miranda P, Elamsson K, Johansson EDB. Plasma levels of levonorgestrel in women during longterm use of Norplant. Contraception. 1981 feb 1;23(2):197-209.