Effect of six antiretroviral drugs (delavirdine, stavudine, lamivudine, nelfinavir, amprenavir and lopinavir/ritonavir in association) on albino pregnant rats (Rattus norvegicus Albinus, Rodentia, Mammalia): biological assay

OBJECTIVE

To compare the chronic effects of antiretrovirals (lamivudine, stavudine, delavirdine, nelfinavir, amprenavir and an association of lopinavir/ritonavir) on albino pregnant rats.

DESIGN

Review.

SETTING

Department of Obstetrics, Federal University of São Paulo (UNIFESP), São Paulo, SP, Brazil.

METHODS

This was a comparative retrospective study formed by 18 groups of 10 pregnant rats each, which were nearly three months of age and weighed 200 g. All of them were medicated every day using a stomach probe, while the control group was given 1 mL of distilled water. The study groups received lamivudine (at 5, 15 and 45 mg/kg/day); stavudine (at 1, 3 and 9 mg/kg/day); nelfinavir (at 40, 120 and 360 mg/kg/day); amprenavir (at 46, 138 and 414 mg/kg/day); lopinavir/ritonavir (at 12.8/3.2, 38.4/9.6 and 115/28.8 mg/kg/day) and delavirdine (at 20 and 60 mg/kg/day). These represented 1, 3 and 9 times the human therapeutic dose, except for the last drug, for which the 9-times dose was not used. Maternal, litter and placental weights, implantation and reabsorption numbers, major external fetal malformations and fetal and maternal deaths were evaluated. The Kruskal-Wallis test was used to compare quantitative variables and the chi-square test was used to compare qualitative variables.

RESULTS

At all three doses, stavudine increased the maternal weight (p=0.001), while lamivudine at 3- and 9-times doses reduced it (p<0.001). Amprenavir at all of the doses, and lopinavir/ritonavir at 3- and 9-times doses, caused higher rates of maternal death (p<0.001). Regarding the fetuses, none of the antiretroviral drugs studied were harmful with regard to implantation, reabsorption, teratogenity and mortality (p>0.05). Stavudine at all doses reduced the litter weights (p<0.001); however, lamivudine at the usual and 3-times doses, delavirdine at 3-times dose, and amprenavir at 3-times dose increased the litter weight (p<0.001).

CONCLUSION

In the maternal compartment, we observed lethal toxicity in the pregnant rats that received amprenavir and ritonavir/lopinavir; and maternal weight change with lamivudine and stavudine. In the fetal compartment, adverse effects were observed in relation to litter weight from stavudine, lamivudine, delavirdine and amprenavir.

A morphological and biochemical appraisal of the liver and renal effects of lamivudine on rat pregnancy

No data exist on the perinatal safety of lamivudine alone, as it is used in combination with other antiretroviral agents. Until now, only preliminary data on the lamivudine-zidovudine combination have been available, thus we decided to examine the gross maternal and fetal effects of lamivudine administered alone during the entire period of rat pregnancy. Forty pregnant animals were assigned at random to four groups (C1 = control; E1 = 5 mg/kg; E2 = 15 mg/kg; E3 = 45 mg/kg) from day 0 up to the 20th day of gestation. These doses were divided into two daily administrations by gavage. Controls (n = 10) received distilled water in the same schedule. At term-pregnancy, the rats were deeply anesthetized and blood samples were collected for alanine and aspartate aminotransferases, creatinine and urea determinations. Fragments of maternal and fetal livers and kidneys were taken and processed for histopathological study. In all groups blood transaminases were within the normal limits, as were the levels of creatinine and urea, thus indicating that treatment with lamivudine during the entire gestation was essentially devoid of liver or kidney effects which could result in altered metabolic parameters. Morphological (light microscopy) studies revealed that no significant effects of the drug could be detected regarding either maternal or fetal organs of the E1 and E2 groups. However, the maternal hepatocytes in the E3 group showed heterochromatic nuclei. In addition, there was some fatty infiltration, congested sinusoids and portal dilatation. Maternal kidneys in the E3 group revealed vascular dilation around the convoluted tubules. It is concluded that only doses of lamivudine used during the entire gestation in doses well above the usual human doses could be considered to be potentially hepatotoxic for the pregnant rat.

Morphological and morphometric changes in the cervix uteri of the rat at term pregnancy induced by hyaluronidase

Intracervix injection of hyaluronidase during pregnancy has been proposed to accelerate cervix ripening. We evaluated the morphological and morphometric changes of the uterine cervix of pregnant rats, caused by the action of this enzyme. Ten female rats were equally divided between an experimental group (G II) and a control group (G I). On the 20th day of pregnancy, under light microscopy, a greater thinning of the superficial muciferous epithelium, with lamina propria rich in blood vessels and in eosinophils was found in G II. The histometric count of G II showed a smaller number of collagen fibers (average 248 vs 552 in the control group) and a greater concentration of eosinophils (average 18.20 vs 9.20 in the control group). The Student's t-test showed a significant difference in collagen fibers (p < 0.0001) and in eosinophils (p < 0.0007). The action of this enzyme caused a predominance of flaccid connective tissue, a lower concentration of collagen fibers and an increased concentration of eosinophils, confirming its utilization in cervix ripening.