1 Department of Obstetrics and Gynaecology, Prince of Wales Hospital, 2 Department of Pharmacology and 3 Department of Obstetric and Gynaecology, The Chinese University of Hong Kong, Shatin, Hong Kong
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Abstract |
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Key words: human/naproxen/placental transfer/pregnancy/teratogenicity
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Introduction |
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The use of drugs in reproductive age women is of particular concern because of potential teratogenic effects. NSAIDs are commonly used among women of reproductive age for conditions such as dysmenorrhoea, menorrhagia, musculoskeletal pain and tension headache (Dawood, 1993). A population-based study in Denmark revealed that 7.5% of all pregnant women had taken NSAIDs within 12 weeks before conception (Olesen et al., 1999
).
Theoretically, NSAIDs may cause adverse fetal effects because of their ability to disturb the homeostasis of prostaglandins, which might result in fetal malformation (Klein et al., 1984). Indeed, aspirin and indomethacin were known to have adverse effects on human fetus and neonates if given near term (Ostensen, 1998
), and teratogenic effects of the older generations of NSAID have been demonstrated in animal experiments (McGarrity et al., 1981
). However, similar information relating to newer generations of NSAIDs is scanty. Nielsen et al. recently reported an association between the use of NSAIDs before or during early pregnancy and a higher miscarriage rate (Nielsen et al., 2001
). Whether this increase in early pregnancy loss is mediated through disturbances in early fetal development is unknown.
The teratogenicity of different drugs depends not only on their direct effect on the embryos, but also on how effectively these drugs are transported across the placenta. Naproxen has been associated with premature closure of the ductus arteriosus and severe pulmonary hypertension in infants born to mothers taking naproxen (Wilkinson et al., 1979). However, its teratogenic potential and its passage across the placenta at an early stage of pregnancy have never been studied. The objective of this project was to investigate the placental transfer of naproxen, a commonly used NSAID, in the first trimester of human pregnancy.
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Materials and methods |
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Two oral doses of 500 mg naproxen (Apo-Naproxen; Apotex Inc., Toronto, Canada) were given before surgery, the first at 22:00 on the night before operation and the second 4 h before the scheduled operation time. All operations were performed between 08:30 and 13:00. Surgical termination of pregnancy was performed under general anaesthesia, using a standard protocol. Propofol and fentanyl were used for induction of anaesthesia and analgesia respectively, and anaesthesia was maintained by inhalation of 70% nitrous oxide and 1% isofluorane mixed with oxygen. A maternal venous blood sample was taken just before induction of general anaesthesia. After induction of general anaesthesia, transvaginal ultrasound examination was performed to confirm fetal viability and to measure the fetal crownrump length. Coelocentesis and amniocentesis were performed by fine needle aspiration under ultrasound guidance transvaginally according to protocols previously reported (Lau et al., 1998). Surgical termination of pregnancy was then performed by suction curettage after the cervix was dilated with Hegar dilators to a size corresponding to the gestational age. Fetal parts were identified after the surgical procedure, washed with normal saline to remove traces of maternal blood, and collected for further analysis.
Maternal serum was separated from maternal blood by centrifugation at 1250 g for 10 min. All samples were stored at 70°C, pending further analyses. The fetus was weighed, homogenized in physiological saline and then centrifuged to clear samples before analysis. Naproxen concentrations in each of four specimens were measured by high performance liquid chromatography with UV detection. The minimal detection limits of the assay were 10 ng/ml for amniotic fluid, coelomic fluids and fetal tissue samples, and 20 ng/ml for maternal serum samples. The inter-batch assay of naproxen was reproducible and precise, with a coefficient of variation of 4.94%. Naproxen metabolites in the samples were not analysed.
Drug concentrations in serum, amniotic and coelomic samples were expressed in drug per unit volume (per ml), while those in fetal tissue were expressed as drug per unit weight (per g). Since the density of fetal tissue should be >1 g/ml, the numerical value of the drug concentration should be higher when expressed in µg/ml than when expressed in µg/g. Therefore, interpretation of ratios involving fetal tissue drug concentrations should be cautious.
Wilcoxon signed ranks test was used to determine the differences in drug concentration between these samples, and Pearson correlation analysis was used for the rest of the tests.
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Results |
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Naproxen was detected in all maternal serum, coelomic fluid, amniotic fluid and fetal tissue samples. Maternal serum naproxen concentrations (mean ± SD) ranged from 25.3 to 88.15 µg/ml (69.5 ± 12.2). Fetal tissue drug concentration ranged from 1.8 to 10.6 µg/g (6.4 ± 2.4). Coelomic fluid concentration ranged from 0.42 to 5.92 µg/ml (1.85 ± 1.03) and amniotic fluid drug concentration from 0.03 to 0.53 µg/ml (0.14 ± 0.11). There were highly significant differences between drug concentrations in maternal serum and fetal tissue; fetal tissue and coelomic fluid; and coelomic fluid and amniotic fluid; (P < 0.001). Figure 1 shows the relationship between naproxen concentrations in different samples and gestational age. There were significant correlations between gestational age and fetal drug concentration (r = 0.59, P = 0.001), and amniotic fluid drug concentration (r = 0.47, P = 0.013), but not between gestational age and coelomic fluid (r = 0.1).
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Discussion |
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To our knowledge, only limited studies have been reported in the English medical literature concerning in-vivo studies on the transplacental transfer of drugs in human during the first trimester pregnancy, mostly on drugs used in general anaesthesia (Jorgensen et al., 1988; Jauniaux et al., 1996
, 1998
; Shannon et al., 1998
) and antibiotics (Dekel et al., 1980
; Nau et al., 1981
; Heisterberg, 1984
; Karhunen, 1984
; Jorgensen et al., 1987
). All these studies used similar methodology, which was to study drug concentration in different fetal compartments after the maternal administration of a drug before termination of pregnancy. By direct sampling of the drug concentration in different compartments of the embryo, the drug concentration and the transfer ratio could be determined. This model is closest to the real situation (Jauniaux and Gulbis, 2000a
), and was therefore adopted for the current study.
Our results have confirmed that naproxen crosses the first trimester human placenta. Naproxen was found in all samples collected from all three embryonic compartments, namely the amniotic cavity, the extra-embryonic cavity and the fetus. However, there were significant differences between drug concentrations among these compartments, the highest concentration being found in the fetus, and the lowest in the amniotic cavity. This gradient of drug concentration is probably due to different mechanisms involved in placental drug transfer in early pregnancy as proposed by Jauniaux and Gulbis. They proposed that coelomic fluid is an ultrafiltrate of maternal serum, with the chorionic plate acting as the membrane (Jauniaux and Gulbis, 2000b). On the other hand, amniotic fluid is a combination of transudate from fetal skin and transfer from coelomic fluid. Drugs enter the fetal tissue either directly through villous tissue or retrieval by secondary yolk sac from extracoelomic fluid (Gulbis et al., 1998
).
Most drugs cross the placenta by passive diffusion, which is affected by molecular weight, liposolubility, ionization and protein binding (Garland, 1998). Naproxen is a highly lipid soluble molecule with a low molecular weight of 230 Daltons. These chemical characteristics enable naproxen to cross biological membranes easily. A significant amount of naproxen was detected in the fetal tissue and less in the extracoelomic cavity, suggesting that naproxen crosses villous tissue more readily than the chorionic leave. At therapeutic concentrations, >99% of naproxen is tightly bound to albumin (Allison et al., 1985
). Thus, this explained why the coelomic and fetal tissue naproxen concentration attained was only 815% of the corresponding serum concentration. Since the amniotic membrane has a lower rate of drug transfer than the chorionic leave (Jauniaux and Gulbis, 2000b
), the naproxen concentration in amniotic fluid was lowest among all the fetal compartments.
We have found that naproxen concentration increased in both the amniotic fluid and fetal tissue with advancing gestational age. This increase in transfer might be due to the development and maturation of villous tissue, which improves the maternalfetal transfer into these two compartments. The lack of gestation dependency of naproxen concentration in coelomic fluid in our study further supports the concept that the transfer of naproxen is independent of chorionic villi, but instead occurs via ultra-filtratation through the chorionic laeve.
Our results show that the placental transfer of naproxen is significantly different from that of diclofenac (Siu et al, 2000), which is another NSAID. In the diclofenac study, the fetal concentration was close to the maternal concentration, with a mean fetal/maternal ratio of 1.05. In contrast, the mean fetal/maternal ratio of naproxen was 0.092, which was only 10% of the maternal drug concentration. Moreover, the fetal naproxen concentration increases with gestational age, while fetal diclofenac decreases with gestational age. These differences may represent different placental transfer mechanisms of these two drugs. Our observations suggest that diclofenac has a higher potential to induce fetal effects because of a much higher rate of fetal transfer.
Previous studies on the placental transfer of propofol (Jauniaux et al., 1998) and fentanyl (Cooper et al., 1999
) yielded somewhat different results. Neither propofol nor fentanyl was detectable in any coelomic fluid or amniotic fluid samples collected within 30 min after a single i.v. injection. Jauniaux and Gulbis hypothesized that coelomic fluid has a slow turnover in nature, therefore it may take longer for a drug to reach the coelomic cavity and thus the amniotic cavity (Jauniaux and Gulbis, 2000b
).
In this study, subjects were prescribed two doses of naproxen before pregnancy termination. This regime was different from the propofol and fentanyl studies in which only a single dose of drug was given. A multiple-dose regime was chosen in order to mimic the real clinical situation, since naproxen is usually prescribed in multiple doses. Our dosage regime ensured (i) the establishment of a maternal drug level within therapeutic range and (ii) the establishment of equilibrium between maternal and fetal compartments. Our results have confirmed that the mean maternal serum naproxen concentration of 69.5 µg/ml achieved in our study was similar to the mean therapeutic serum concentration of 50 µg/ml (Allison et al., 1985). However, most patients will be taking more doses in real clinical practice, and the present experiment did not enable the study of potential accumulation of drug with repeated doses. In other words, although only small amounts of naproxen were present in the fetus after ingestion of two standard doses, the drug may accumulate to a much higher level if the mother is taking naproxen daily.
In conclusion, naproxen crosses the placenta readily and the transfer ratio increases with gestation. Though the fetal/maternal ratio of naproxen is small, we have no information on whether this small amount of naproxen would cause any adverse effects on the developing human fetus. With the current evidence from rat embryo culture that naproxen could induce cleft palate (Montenegro and Palomino, 1990), naproxen should be regarded as a potential teratogenic drug until proven otherwise. On the other hand, the much lower rate of placental transfer of naproxen compared with diclofenac suggests that the former is less likely to induce teratogenicity. Nonetheless, we believe that women of reproductive age who are taking NSAIDs regularly should be warned of the possible fetal side-effects.
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Acknowledgements |
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Notes |
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References |
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Castellucci, M., Kosanke, K., Verdenelli, F. et al. (2000) Villous sprouting: fundamental mechanisms of human placental development. Hum. Reprod. Update., 6, 485494.
Cooper, J., Jauniaux, E., Gulbis, B. et al. (1999) Placental transfer of fentanyl in early human pregnancy and its detection in fetal brain. Br. J. Anaesth., 82, 929931.
Dawood, M.Y. (1993) Nonsteroidal anti-inflammatory drugs and reproduction. Am. J. Obstet. Gynecol., 169, 12551265.[ISI][Medline]
Dekel, A., Elian, I., Gibor, Y. et al. (1980) Transplacental passage of cefazolin in the first trimester of pregnancy. Eur. J. Obstet. Gynecol. Reprod. Biol., 10, 303307.[ISI][Medline]
Garland, M. (1998) Pharmacology of drug transfer across the placenta. Obstet. Gynecol. Clin. N. Am., 25, 2142.[ISI][Medline]
Gulbis, B., Jauniaux, E., Cotton, F. et al. (1998) Protein and enzyme patterns in the fluid cavities of the first trimester gestational sac: relevance to the absorptive role of secondary yolk sac. Mol. Hum. Reprod., 4, 857862.[Abstract]
Hawkins, C. (1998) Audit and use of NSAIDs. Lancet, 352, 658.
Heisterberg, L. (1984) Placental transfer of metronidazole in the first trimester of pregnancy. J. Perinat. Med., 12, 4345.[ISI][Medline]
Jauniaux, E. and Gulbis, B. (2000a) In vivo investigation of placental transfer early in human pregnancy. Eur. J. Obstet. Gynecol. Reprod. Biol., 92, 4549.[ISI][Medline]
Jauniaux, E. and Gulbis, B. (2000b) Fluid compartments of the embryonic environment. Hum. Reprod. Update., 6, 268278.
Jauniaux, E., Jurkovic, D., Lees, C. et al. (1996) In-vivo study of diazepam transfer across the first trimester human placenta. Hum. Reprod., 11, 889892.[Abstract]
Jauniaux, E., Gulbis, B., Shannon, C. et al. (1998) Placental propofol transfer and fetal sedation during maternal general anaesthesia in early pregnancy. Lancet, 352, 290291.[ISI][Medline]
Jorgensen, N.P., Walstad, R.A. and Molne, K. (1987) The concentrations of ceftazidime and thiopental in maternal plasma, placental tissue and amniotic fluid in early pregnancy. Acta Obstet. Gynecol. Scand., 66, 2933.[ISI][Medline]
Jorgensen, N.P., Thurmann-Nielsen, E. and Walstad, R.A. (1988) Pharmacokinetics and distribution of diazepam and oxazepam in early pregnancy. Acta Obstet. Gynecol. Scand., 67, 493497.[ISI][Medline]
Karhunen, M. (1984) Placental transfer of metronidazole and tinidazole in early human pregnancy after a single infusion. Br. J. Clin. Pharmacol., 18, 254257.[ISI][Medline]
Klein, K.L., Clark, K.E. and Scott, W.J. (1984) Prostaglandin synthesis in rat embryo tissue: the effect of non-steroidal anti-inflammatory drugs in vivo and ex vivo. Prostaglandins, 27, 659672.[Medline]
Lau, T.K., Fung T.Y., Wong Y.F. et al. (1998) A study of fetal sex determination in coelomic fluid. Gynecol. Obstet. Invest., 45, 1618.[ISI][Medline]
McGarrity, C., Samani, N., Beck, F. et al. (1981) The effect of sodium salicylate on the rat embryo in culture: an in vitro model for the morphological assessment of teratogenicity. J. Anat., 133, 257269.[ISI][Medline]
Montenegro, M.A. and Palomino, H. (1990) Induction of cleft palate in mice by inhibitors of prostaglandin synthesis. J. Craniofac. Genet. Dev. Biol., 10, 8394.[ISI][Medline]
Moore, N., Verschuren, X., Montout, C. et al. (2000) Excess costs related to non-steroidal anti-inflammatory drug utilization in general practice. Therapie, 55,133136.
Nau, H., Welsch, F., Ulbrich, B. et al. (1981) Thiamphenicol during the first trimester of human pregnancy: placental transfer in vivo, placental uptake in vitro, and inhibition of mitochondrial function. Toxicol. Appl. Pharmacol., 60, 131141.[ISI][Medline]
Nielsen, G.L., Sorensen, H.T., Larsen, H. et al. (2001) Risk of adverse birth outcome and miscarriage in pregnant users of non-steroidal anti-inflammatory drugs: population based observational study and case-control study. Brit. Med. J., 322, 266270.
Olesen, C., Steffensen, F.H., Nielsen, G.L. et al. (1999) Drug use in first pregnancy and lactation: a population-based survey among Danish women. Eur. J. Clin. Pharmacol., 55, 139144.[ISI][Medline]
Ostensen, M. (1998) Nonsteroidal anti-inflammatory drugs during pregnancy. Scand. J. Rheumatol., 27, 128132.
Shannon, C., Jauniaux, E., Gulbis, B. et al. (1998) Placental transfer of fentanyl in early human pregnancy. Hum. Reprod., 13, 23172320.[Abstract]
Siu, S.S.N., Yeung, J.H.K. and Lau, T.K. (2000) A study on placental transfer of diclofenac in first trimester of human pregnancy. Hum. Reprod., 15, 24232425.
Van den Veyver, I.B. and Moise, K.J. (1993) Prostaglandin synthetase inhibitors in pregnancy. Obstet. Gynecol. Surv., 48, 493502.[Medline]
Wilkinson, A.R., Aynsley-Green, A., Mitchell, M.D. (1979) Persistent of pulmonary hypertension and abnormal prostaglandin E levels in preterm infants after maternal treatment with naproxen. Arch. Dis. Child., 54, 942945.[Abstract]
Submitted on September 13, 2001; accepted on November 11, 2001.