17-hydroxy progesterone caproate for preterm labor prevention: final blood levels




We read with great interest the study correlating 17-hydroxy progesterone caproate (17-OHPC) levels with preterm delivery. We have the following comments:


The levels of 17-OHPC correlated with progesterone and hydroxy-progesterone levels. Is it possible that the method used was measuring partly these hormones in addition to 17-OHPC levels that could be an overlap in detection?


The higher C-reactive protein level in the 17-HPC group could be an intrinsic difference between the 2 groups and not the consequence of 17-OHPC injection; thus, it would have been more convincing had these markers been studied at baseline before 17-OHPC injections were started.


In a previous study by the same group, the peak plasma concentration of 17-HPC was attained at 24 hours after the injection. The results of the study could be stronger had the levels been taken at a specified time in relation to the last injection, especially because the steady state was not reached until at epoch 2 (32-35 weeks’ gestation). Furthermore, the mean 17-OHPC level in singleton pregnancies appears to be approximately 15-18 ng/mL, whereas the level in twin pregnancies was approximately 10-13 ng/mL. Similarly, the C troughs/peaks were 14.1 ± 5.6 ng/mL (range, 10–18.1 ng/mL)/22.6 ± 9.5 ng/mL (range, 15.8–27.4 ng/mL) and 9.7 ± 2.8 ng/mL (range, 8.0–12.0 ng/mL)/17 ± 6.7 ng/mL (range, 12.0–22.0 ng/mL) in singleton and twin pregnancies; respectively. This raises the possibility that the lack of efficacy of the drug in twin pregnancies might be the result of inadequate blood level of the drug because of the greater volume of distribution in twin pregnancies.


One of the confounders for gestational age at delivery (the combined twin birthweight) was not controlled for. This might be of importance in twin pregnancies in which mechanical factors might play a major role in the determination of the gestational age at delivery.


It would have been interesting to determine intrapartum 17-OHPC levels in term and preterm deliveries. This would be more reflective of the actual level that was associated with a term or preterm delivery rather than a level that was obtained at 28 weeks, for example.


Finally, we fully agree that a similar study in singleton pregnancies would be of great value to identify differences that might give insight into the pathogenesis of preterm delivery or an explanation of the effectiveness of 17-OHPC in singleton, but not twin, pregnancies.

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May 13, 2017 | Posted by in GYNECOLOGY | Comments Off on 17-hydroxy progesterone caproate for preterm labor prevention: final blood levels

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