Chemotherapy in a pregnant rat model. 1. Mitomycin-C: pregnancy-specific kinetics and placental transfer

Renal and Bladder Cancer During Pregnancy: A Review of 47 Cases and Literature-based Recommendations for Management

OBJECTIVE

To provide contemporary gestational age-specific recommendations for management, a retrospective series of patients with renal or bladder cancer during pregnancy is reported.

METHODS

Obstetric and oncological data of pregnant patients with a diagnosis of renal or bladder cancer were selected from the worldwide registry of the International Network of Cancer, Infertility and Pregnancy. In addition, the literature was reviewed for recent case reports since last reviews in 2014 for renal cancer and 2004 for bladder cancer.

RESULTS

International Network of Cancer, Infertility and Pregnancy registered 22 cases (14 renal cancer and 8 bladder cancer), diagnosed between 1999 and 2017, and the literature reported 15 cases with renal cancer and 10 cases with bladder cancer between 2004 and 2019. Most common symptoms for renal and bladder cancer were pain (28%) and hematuria (66%), respectively. In more than half of the patients, surgical treatment was performed during pregnancy. Preterm deliveries were mostly medically induced (12 of 17, 71%) and all patients with a planned delivery before 34 weeks had advanced cancer. For renal and bladder cancer respectively, 79% and 87% of patients obtained complete remission. Advanced cancer stages had worse prognosis; 3 of 7 patients with known follow-up deceased within 15 months after diagnosis.

CONCLUSION

Gestational age at diagnosis determines further management of renal and bladder cancers during pregnancy. Advanced stages challenge decision-making. The maternal needs for immediate treatment, and the neonatal risks including the impact of a preterm delivery should be discussed in a multidisciplinary setting while respecting the patient's autonomy.

Toxicokinetics of N-ethyl-2-pyrrolidone and its metabolites in blood, urine and amniotic fluid of rats after oral administration

The toxicokinetics of N-ethyl-2-pyrrolidone (NEP), an embryotoxic organic solvent, has been studied in Sprague-Dawley rats after oral exposure. NEP and its metabolites 5-hydroxy-N-ethyl-2-pyrrolidone (5-HNEP) and 2-hydroxy-N-ethylsuccinimide (2-HESI) were measured in plasma of pregnant and non-pregnant rats, and fetuses after NEP administration by gavage for 14 consecutive days at 50 mg/kg/day, and in plasma of non-pregnant rats after a single NEP administration. Additionally, amniotic fluid and 24-h urine samples of the pregnant rats were analyzed for NEP metabolites. Furthermore, 24-h urine samples from a repeated dose 28-day oral toxicity study in female (non-pregnant) and male rats administered developmentally non-toxic (0, 5, and 50 mg/kg/day) or toxic (250 mg/kg/day) doses of NEP were analyzed. Median peak plasma concentrations in non-pregnant rats after a single dose and repeated doses were 551 and 611 (NEP), 182 and 158 (5-HNEP), and 63.8 and 108 µmol/L (2-HESI), respectively; whereas in pregnant rats and fetuses 653 and 619 (NEP), 80.5 and 91.7 (5-HNEP) and 77.3 and 45.7 µmol/L (2-HESI) were detected. Times to reach maximum plasma concentrations for NEP, 5-HNEP, and 2-HESI were 1, 4, and 8 h, respectively, and were comparable to N-methyl-2-pyrrolidone (NMP) and its corresponding metabolites. In pregnant rats, plasma elimination of NEP and metabolite formation/elimination was much slower compared to non-pregnant rats and efficient placental transfer of NEP was observed. Our data, overall, suggest differences in the toxicokinetics of chemicals between pregnant and non-pregnant rats which need to be addressed in risk assessment, specifically when assessing developmental toxicants such as NEP.

Genotoxic sensitivity of the developing hematopoietic system

Genotoxic sensitivity seems to vary during ontogenetic development. Animal studies have shown that the spontaneous mutation rate is higher during pregnancy and infancy than in adulthood. Human and animal studies have found higher levels of DNA damage and mutations induced by mutagens in fetuses/newborns than in adults. This greater susceptibility could be due to reduced DNA repair capacity. In fact, several studies indicated that some DNA repair pathways seem to be deficient during ontogenesis. This has been demonstrated also in murine hematopoietic stem cells. Genotoxicity in the hematopoietic system has been widely studied for several reasons: it is easy to assess, deals with populations cycling also in the adults and may be relevant for leukemogenesis. Reviewing the literature concerning the application of the micronucleus test (a validated assay to assess genotoxicity) in fetus/newborns and adults, we found that the former show almost always higher values than the latter, both in animals treated with genotoxic substances and in those untreated. Therefore, we draw the conclusion that the genotoxic sensitivity of the hematopoietic system is more pronounced during fetal life and decreases during ontogenic development.

Simultaneous determination of abacavir and zidovudine from rat tissues using HPLC with ultraviolet detection

A simple high-performance liquid chromatography (HPLC) method has been developed and validated for the simultaneous determination of abacavir and zidovudine (AZT) in rat plasma, amniotic fluid, fetal, and placental tissues. Extraction of abacavir, AZT, and the internal standard, azidouridine (AZDU) in amniotic fluid was carried out by protein precipitation. Extraction from plasma, fetal and placental homogenates was achieved by using a salting out technique. Chromatographic separation was performed using a C8 column (150 mm x 4.6 mm, 5 microm). The mobile phase consisted of 12% acetonitrile in 25 mM sodium phosphate buffer (adjusted to pH 7 with sodium hydroxide) for the fetus, placenta, plasma and amniotic fluid samples at a flow rate of 0.8 mL/min. The method was validated over the range from 0.05 to 50 microg/mL for both abacavir and AZT in the four biological matrices. The absolute recovery of abacavir ranged from 79 to 94%, while AZT recoveries ranged from 79 to 90% in the different biological matrices. The internal standard recovery ranged from 90 to 92%. Acceptable intra- and inter-day assay precision (<10% R.S.D.) and accuracy (<10% error) were observed over 0.05-50 microg/mL for all four matrices.

Effects of maternally administered drugs on the fetal and neonatal kidney

The number of pregnant women and women of childbearing age who are receiving drugs is increasing. A variety of drugs are prescribed for either complications of pregnancy or maternal diseases that existed prior to the pregnancy. Such drugs cross the placental barrier, enter the fetal circulation and potentially alter fetal development, particularly the development of the kidneys. Increased incidences of intrauterine growth retardation and adverse renal effects have been reported. The fetus and the newborn infant may thus experience renal failure, varying from transient oligohydramnios to severe neonatal renal insufficiency leading to death. Such adverse effects may particularly occur when fetuses are exposed to NSAIDs, ACE inhibitors and specific angiotensin II receptor type 1 antagonists. In addition to functional adverse effects, in utero exposure to drugs may affect renal structure itself and produce renal congenital abnormalities, including cystic dysplasia, tubular dysgenesis, ischaemic damage and a reduced nephron number. Experimental studies raise the question of potential long-term adverse effects, including renal dysfunction and arterial hypertension in adulthood. Although neonatal data for many drugs are reassuring, such findings stress the importance of long-term follow-up of infants exposed in utero to certain drugs that have been administered to the mother.

Determination of didanosine in maternal plasma, amniotic fluid, fetal and placental tissues by high-performance liquid chromatography-tandem mass spectrometry

A rapid and efficient high-performance liquid chromatography (HPLC)-tandem mass spectrometry method for the determination of didanosine concentrations in maternal rat plasma, amniotic fluid, placental and fetal tissue samples has been developed and validated. Tissue samples were homogenized in optima water and centrifuged. The supernatant was subjected to solid-phase extraction (SPE) prior to analysis. Plasma and amniotic fluid samples were extracted without pretreatment. An Agilent 1100 Series HPLC coupled with a Micromass Quattro II triple quadrupole mass spectrometer was used for all analyses. Chromatographic resolution was achieved on a Nova-Pak phenyl analytical column (2.0 x 150 mm, 4 microm particle size) equipped with a Phenomenex Security-guard phenyl guard cartridge (2.0 x 4.0 mm) using 60% methanol in 10 mm ammonium acetate buffer mobile phase for all matrices at a flow rate of 0.15 mL/min. The method yields retention times of 2.9 min for didanosine and 3.0 min for the internal standard, stavudine. Limits of detection were 1 ng/mL for all matrices. Recoveries were 70% or greater for both compounds in the different matrices. Within- and between-run precision (%RSD) and accuracy (%error) was less than 15% for all matrices.

Simultaneous determination of zidovudine and lamivudine from rat tissues by liquid chromatography/tandem mass spectrometry

A simple liquid chromatography/tandem mass spectrometry (LC/MS/MS) method has been developed and validated for the simultaneous determination of zidovudine (AZT) and lamivudine (3TC) in rat plasma, amniotic fluid, placental, and fetal tissues. Samples were processed by acetonitrile precipitation. Chromatography was performed using a C18 column (5 microm, 150 x 3.9 mm i.d). The mobile phase consisted of 30% methanol and 7.5 mM ammonium acetate (pH 6.5). The method was validated in the range of 0.05-25 microg/mL for both 3TC and AZT in the four biological matrices. Finally, the method was applied to a study involving fetal transport following co-administration of these compounds at a dose of 25 mg/kg each in a pregnant rat.

Determination of lamivudine in plasma, amniotic fluid, and rat tissues by liquid chromatography

An HPLC method for the quantification of lamivudine (3TC) in rat plasma, amniotic fluid, placental and fetal tissues has been developed, validated and applied to the study of the placental transport of this drug in the pregnant rat. Placental and fetal tissues were processed using liquid-liquid extraction enhanced by salting out the sample using a saturated solution of ammonium sulfate. Plasma and amniotic fluid samples were processed by protein precipitation using 2 M perchloric acid. Reverse phase chromatography was performed using a phenyl column (5 microm, 150 mm x 2 mm i.d.) under a flow rate of 0.2 ml/min. The mobile phase consisted of 5% methanol in 20 mM dibasic phosphate buffer (pH 6). The method was validated over the range from 0.1 to 50 microg/ml for plasma and amniotic fluid and 0.2-50 microg/ml for the placental and fetal tissues.

Pharmacokinetics of intravenous acyclovir, zidovudine, and acyclovir-zidovudine in pregnant rats

The pharmacokinetics and placental transfer of acyclovir and zidovudine monotherapies and acyclovir-zidovudine combination therapy were compared in the pregnant rat. Timed-pregnancy Sprague-Dawley rats were used for the study. Doses of 60 mg of each drug/kg of body weight in monotherapy and in combination therapy were given by intravenous bolus, and samples of maternal plasma, amniotic fluid, fetal tissue, and placental tissue were collected over a period of 8 h postdose. Concentrations of each drug in the various matrices were measured by high-performance liquid chromatography. All data were analyzed by using WinNonlin. A one-compartment model with first-order elimination was used to fit the AZT plasma data from the combination therapy rats, but the plasma data from the other groups were fit to a two-compartment model. Tissue data were analyzed by noncompartmental analysis to generate area-under-the-concentration-time-curve values. Implementation of the combination therapy altered the pharmacokinetics of each drug compared to its monotherapy pharmacokinetics. The combination of these two drugs may potentiate fetal and amniotic fluid exposures to each drug.

Determination of acyclovir in maternal plasma, amniotic fluid, fetal and placental tissues by high-performance liquid chromatography

Acyclovir [9-[(2-hydroxyethoxy)-methyl]-guanosine, Zovirax, ACV] is a synthetic purine nucleoside analog active against herpes simplex virus types 1 (HSV-1), 2 (HSV-2), and varicella zoster virus. Acyclovir has frequently been used in HSV-2 seropositive mothers to prevent prenatal transmission of herpes virus to their unborn children. A fast and reproducible HPLC method for the determination of the highly polar acyclvoir in maternal rat plasma, amniotic fluid, placental tissue, and fetal tissue has been developed and validated. Plasma and amniotic fluid samples were prepared by protein precipitation using 2 M perchloric acid and syringe filtering. Tissue samples were homogenized in distilled water, centrifuged, and extracted using a C(18) solid-phase extraction method prior to analysis. Baseline resolution was achieved for acyclovir and the internal standard gancyclovir, an anti-viral of similar structure to acyclovir, using an Agilent Eclipse XDB C(8) column (150 x 2.1 mm, 5 microm). The mobile phase used for the plasma and amniotic fluid was 10 mM acetate/citrate buffer-3.7 mM aqueous octanesulfonic acid (87.5:12.5, v/v) at a flow-rate of 0.2 ml/min. The mobile phase used for the tissue samples was 30 mM acetate/citrate buffer with 5 mM octanesulfonic acid-acetonitrile (99:1, v/v). Both aqueous mobile phase portions were pH adjusted to 3.08. All separations were done using an Agilent 1100 Series HPLC system with UV detection of 254 nm. The assay was validated for each matrix over a range of 0.25-100 microg/ml over 3 days using five replicates of three spiked concentrations. The relative standard deviation and percent error for each validation data set was <15% for middle and high quality control (QC) points and <20% for all low QC points. All calibration curves showed good linearity with an R(2)>0.99. The extraction efficiency for recovery of acyclovir from all matrices was >80%.

Determination of 3'-azido-2',3'-dideoxyuridine in maternal plasma, amniotic fluid, fetal and placental tissues by high-performance liquid chromatography

3'-Azido-2',3'-dideoxyuridine (AZDU, Azddu, CS-87) is a nucleoside analog of 3'-azido-3'-deoxythymidine (zidovudine, AZT) that has been shown to inhibit human immunodeficiency virus (HIV-1). AZDU is a potential candidate for treatment of pregnant mothers to prevent prenatal transmission of HIV/AIDS to their unborn children. A rapid and efficient high-performance liquid chromatography (HPLC) method for the determination of AZDU concentrations in rat maternal plasma, amniotic fluid, placental and fetal tissue samples has been developed and validated. Tissue samples were homogenized in distilled water, protein precipitated and extracted using a C-18 solid-phase extraction (SPE) method prior to analysis. Plasma and amniotic fluid samples were protein precipitated with 2 M perchloric acid prior to analysis. Baseline resolution was achieved using a 4.5% acetonitrile in 40 mM sodium acetate (pH 7) buffer mobile phase for amniotic fluid, placenta and fetus samples and with a 5.5% acetonitrile in buffer solution for plasma at flow-rates of 2.0 ml/min. The HPLC system consists of a Hypersil ODS column (150x4.6 mm) with a Nova-Pak C-18 guard column with detection at 263 nm. The method yields retention times of 6.2 and 12.2 min for AZDU and AZT in plasma and 8.3 and 17.6 min for AZDU and AZT in amniotic fluid, fetal and placental tissues. Limits of detection ranged from 0.01 to 0.075 microg/ml. Recoveries ranged from 81 to 96% for AZDU and from 82 to 96% for AZT in the different matrices. Intra-day (n=6) and inter-day (n=9) precision (% RSD) and accuracy (% Error) ranged from 1.48 to 6.25% and from 0.50 to 10.07%, respectively.

Maternal-fetal pharmacokinetics of zidovudine in rats

The disposition of zidovudine (AZT) was investigated in near-term (day 20) pregnant rats after intravenous bolus administration of AZT at 50 mg/kg. A compartmental pharmacokinetic model was developed to describe AZT concentrations in maternal plasma (1), placenta (2), fetus (3), amniotic fluid (4), and the maternal tissue compartment (5). Model equations were fitted simultaneously to all concentration data by NONLIN least-squares regression. The model that best described the AZT concentration data (F test, AIC, sum of weighted squared residuals) incorporated bidirectional transfer between maternal plasma reversible placenta, placenta reversible fetus, placenta reversible amniotic fluid, and maternal plasma reversible tissue compartment. Transfer rate constants (1/h) were as follows: k12, 0.58 +/- 0.41; k21, 47.64 +/- 46.61; k23, 67.50 +/- 42.03; k32, 13.09 +/- 8.80; k24, 0.62 +/- 0.03; k42, 0.32 +/- 0.06; k15, 5.75 +/- 7.00; k51, 4.12 +/- 1.01; and k10, 1.51 +/- 0.80. AZT rapidly distributed into tissue and placenta compartments. However, AZT accumulated more slowly into amniotic fluid. Intercompartmental distributional clearances suggest that the mechanism of maternal-placental, placental-fetal, and fetal-amniotic fluid transfer of AZT was by passive diffusion. This maternal-fetal model for AZT may offer a useful approach for describing the placental transfer kinetics of other antiviral nucleosides as well.

Effects of gender, pregnancy, and anesthesia on the pharmacokinetics of zidovudine in rats

PURPOSE

The effects of gender, pregnancy and anesthesia on the pharmacokinetics of zidovudine (AZT) were studied in rats.

METHODS

Unanesthetized male (MR), female (FR) and pregnant (day 20, PR) rats received 50 mg/kg AZT via a jugular vein cannula. Female (FRA), pregnant (day 20, PRA) and pregnant (day 20, PRR) rats maintained under ketamine: acepromazine:xylazine anesthesia also received 50 mg/kg AZT. Two fetuses were removed at each sampling time from the PRR group. Plasma samples were collected and analyzed by RIA.

RESULTS

With the exception of a lower non-renal clearance in female rats, there were no gender differences in the disposition of AZT. No significant differences were noted in total clearance, non-renal clearance or volume of distribution between pregnant and female rats, however, significant differences in renal clearance values were evident. Anesthesia resulted in decreased total, renal and non-renal clearances in female and pregnant rats. The removal of fetuses during the experiments did not alter the total clearance of AZT in pregnant rats, however, renal clearance and volume of distribution were decreased by cesarian section.

CONCLUSIONS

The rat appears to be a suitable laboratory animal model for investigating AZT disposition during pregnancy. However, results of pharmacokinetic studies when animals are maintained under anesthesia with ketamine:acepromazine:xylazine must be interpreted with caution.

Pharmacology of antineoplastic agents in pregnancy

The use of antineoplastic agents in pregnant women poses obvious risks to both the patient and the developing fetus, particularly during organogenesis. While the use of antineoplastics during pregnancy is often unavoidable, the physician may limit the risks by having a clear knowledge of the pharmacology and teratogenic potential of individual agents. Specific physiologic changes in the pregnant patient, such as enhanced renal excretion of drugs, increased or decreased hepatic function, altered gastrointestinal absorption and enterohepatic circulation, altered plasma protein binding, an increase in plasma volume (50%), and creation of a fluid filled 3rd compartment (amniotic fluid) for water soluble drugs may all significantly influence the pharmacology of antineoplastic agents. These physiological changes may effect the pregnant patients ability to absorb orally administered drugs, metabolize drugs to either active or inactive metabolites, and eliminate cytotoxically active drugs. A resulting reduction in concentration x time (C x T) for drug exposure to the maternal system may reduce the efficacy of the antineoplastic agents, while an increase in C x T may expose the patient and her fetus to undue toxicity. The timing of drug administration to gestational age is also a critical factor for some drugs. While many drugs result in adverse effects on the fetus regardless of gestational age, others appear to pose less of a threat if administered beyond the first trimester. This review addresses the pharmacology, pharmacokinetics and the teratogenic potential of individual antineoplastic agents that are commonly used in pregnant patients. The aim of this review is to help the physician select, on a patient specific basis, antineoplastic agents that avoid at least some of the fetal risk involved while maintaining efficacy in the treatment of the patient.

Chemotherapy in a pregnant rat model. 2.5-fluorouracil: nonlinear kinetics and placental transfer

As more women postpone childbearing into their later reproductive years (M. A. Adams, G. P. Oakley, and J. S. Marks, J. Amer. Med. Assoc. 247, 493, 1982), the incidence of cancer in pregnancy is likely to increase. Information regarding the placental transfer and pharmacokinetics of antineoplastic agents is limited. The purpose of this study was to determine the kinetics of 5-fluorouracil, a fluorinated pyrimidine with known nonlinear kinetics (J. M. Collins, R. L. Dedrick, F. G. King, et al., Clin. Pharmacol. Ther. 28, 235, 1980) in a pregnant rat model and compare maternal and fetal disposition. A significant amount of 5-fluorouracil crosses the placenta and the relative fetal exposure increases in a dose-dependent fashion. In the pregnant rat model, 5-FU exhibited nonlinear pharmacokinetics as reflected by an increasing half-life, and a greater than proportional increase in the area under the concentration-time curve (AUC) with increasing dose. Fetal saturation of elimination occurred at a lower dose than in the maternal compartment. The significance of these findings to observed embryotoxicity is discussed in a pharmacodynamic model relating the pharmacokinetic behavior of a drug to its embryotoxic effects.