PMID- 1905949
OWN - NLM
STAT- MEDLINE
DCOM- 19910813
LR  - 20190828
IS  - 0960-0760 (Print)
IS  - 0960-0760 (Linking)
VI  - 38
IP  - 6
DP  - 1991 Jun
TI  - Intrasubject variability in the pharmacokinetics of ethynyloestradiol.
PG  - 733-6
AB  - Intrasubject and intersubject variability in the metabolism of ethynyloestradiol 
      (EE) was assessed in a cross-over randomized study of 6 women who each received 3 
      months treatment with 50 micrograms EE and 50 micrograms EE with 250 micrograms 
      levonorgestrel (LNG). Blood samples were collected at the end of each treatment 
      month, assayed for EE and the half-life of elimination (Tel) and bioavailability 
      (area under the serum concentration-time curve, AUC) calculated. Intrasubject 
      variability for Tel and AUC varied markedly; the variability was random and not 
      correlated with the formulation administered. The intrasubject variability for 
      Tel and AUC was 31 and 17%, respectively, and intersubject variability 66 and 
      95%. The intersubject range of values was more than 3-fold for both Tel and AUC 
      and the intrasubject range about 2-fold. The pharmacokinetics of EE were not 
      influenced by LNG; mean values for Tel and AUC were 17.3 +/- 5.5 h and 11.1 +/- 
      3.8 ng/ml/h, respectively, when EE was administered alone compared with 16.4 +/- 
      4.8 h and 12.5 +/- 3.9 ng/ml/h when given with LNG. However, EE influenced the 
      metabolism of LNG; Tel for LNG was 19.3 +/- 4.2 h when administered alone and 
      significantly higher (30.0 +/- 11.2 h) when given with EE. There was no 
      correlation between the rate of metabolism of EE and that of LNG. The 
      intrasubject variability shown in this and other studies suggests that genetic 
      factors are less important in intersubject variability than previously thought. 
      Some implications of intrasubject variability are discussed.
FAU - Fotherby, K
AU  - Fotherby K
AD  - Royal Postgraduate Medical School, London, England.
LA  - eng
PT  - Clinical Trial
PT  - Comparative Study
PT  - Journal Article
PT  - Randomized Controlled Trial
PL  - England
TA  - J Steroid Biochem Mol Biol
JT  - The Journal of steroid biochemistry and molecular biology
JID - 9015483
RN  - 3J8Q1747Z2 (Norgestrel)
RN  - 423D2T571U (Ethinyl Estradiol)
RN  - 5W7SIA7YZW (Levonorgestrel)
SB  - IM
MH  - Adult
MH  - Biological Availability
MH  - Drug Interactions
MH  - Ethinyl Estradiol/blood/*pharmacokinetics
MH  - Female
MH  - Half-Life
MH  - Humans
MH  - Levonorgestrel
MH  - Middle Aged
MH  - Norgestrel/blood/pharmacokinetics
EDAT- 1991/06/01 00:00
MHDA- 1991/06/01 00:01
CRDT- 1991/06/01 00:00
PHST- 1991/06/01 00:00 [pubmed]
PHST- 1991/06/01 00:01 [medline]
PHST- 1991/06/01 00:00 [entrez]
AID - 0960-0760(91)90086-K [pii]
AID - 10.1016/0960-0760(91)90086-k [doi]
PST - ppublish
SO  - J Steroid Biochem Mol Biol. 1991 Jun;38(6):733-6. doi: 
      10.1016/0960-0760(91)90086-k.