Uptake of carbamazepine by cucumber plants--a case study related to irrigation with reclaimed wastewater.

Reclaimed wastewater is an important source of irrigation in semiarid and arid zones. Here we report data on carbamazepine (CBZ) uptake by cucumber plants in hydroponic culture and greenhouse experiments using different soil types irrigated with fresh water or reclaimed wastewater. Data obtained from the hydroponic culture experiments suggest that CBZ is mainly translocated by water mass flow, and thus it is concentrated and accumulated to the largest extent in the mature/older leaves. Carbamazepine concentration in cucumber fruits and leaves was negatively correlated with soil organic matter content. The concentrations of CBZ in the roots and stems were relatively low, and most CBZ in the plant (76-84% of total uptake) was detected in the leaves. A greenhouse experiment using fresh water and reclaimed wastewater spiked, or not, with CBZ at 1 µg L(-1) (typical concentration in effluents) revealed that CBZ can be taken up and bioaccumulated from its background concentration in reclaimed wastewater. Bioaccumulation factor (calculated as the ratio of CBZ concentration in the plant to that in the soil solution) for the fruits (0.8-1) was significantly lower than the value calculated for the leaves (17-20). This study emphasizes the potential uptake of active pharmaceutical compounds by crops in organic-matter-poor soils irrigated with reclaimed wastewater and highlights the potential risks associated with this agricultural practice.

Morphological changes in the testis induced by diethylcarbamazine.

Diethylcarbamazine (DEC) had been proved to be highly effective against lymphatic filariasis, however its effect on vertebrate cells remains uncertain. After 12 days treatment with DEC, most of the Leydig cells were hypertrophied with several lipid droplets, and others had no nucleus and presented characteristic steatosis features. Vacuolization of Sertoli cells was also noted. Ultrastructural analyses of DEC-treated testes revealed spermatogonies with morphological characteristics of apoptosis, as shrinkage of cytoplasm and increased chromosomal density. In addition, Leydig cells showed numerous lipid droplets scattered throughout the cytoplasm, multivesicular bodies and giant whorl-like smooth endoplasmic reticulum. Several spermatids presented vacuolated mitochondriae, which were disorganized in relation to the microtubular axis of the flagellae. These results indicate that DEC probably affects the microtubular function, however the present data does not exclude the possibility that DEC also can act directly on enzymatic hormonal pathways.

The in vitro effect of albendazole, ivermectin, diethylcarbamazine, and their combinations against infective third-stage larvae of nocturnally subperiodic Brugia malayi (Narathiwat strain): scanning electron microscopy.

Scanning electron microscopy (SEM) was employed to observe the effects of ivermectin (IVM), diethylcarbamazine (DEC), and albendazole (ALB) alone, and the drugs in combination (ALB+IVM and ALB+DEC) against infective third stage larvae (L3) of nocturnally subperiodic (NSP) Brugia malayi (Narathiwat strain) in vitro. IVM, at a concentration of 10(-4) M, killed L3 within 1-2 h. The SEM data showed damage to the L3 surface and loss of regular cuticular annulations. The cuticles were grooved in the middle region of the body. In comparison with normal L3 before treatment with IVM, the cuticular surface showed transversed striations with periodic annulations. The result demonstrated that IVM showed a larvicidal activity against L3 of NSP B. malayi cultivated in vitro. Compared with those larvae in the control group, the treated larvae had no morphological changes in the cuticular surface at the head, body, and tail regions after cultivation with all drugs alone, and in their combinations at a concentration of 10(-5) M for 7 d. In this system, and at that concentration, only the larvae cultured with ALB alone remained highly motile. Although no morphological changes had been observed by SEM, those drugs used alone (IVM and DEC) and in combinations (ALB+IVM and ALB+DEC), reduced larval motility throughout the experiments at a concentration of 10(-5) M. The minimum lethal concentration (MIC) of IVM against NSP B. malayi was 10(-4) M.

Comparative assessment of the in vitro sensitivity of Brugia malayi infective larvae to albendazole, diethylcarbamazine and ivermectin alone and in combination.

The antifilaricidal drugs ivermectin (IVM), diethylcarbamazine (DEC), and albendazole (ALB), used alone or in combinations against infective third-stage larvae (L3) of nocturnally subperiodic (NSP) Brugia malayi (Narathiwat strain), were tested in vitro for sensitivity, for 7 days. IVM alone reduced larval motility at concentrations of 10(-7), 10(-6), and 10(-5) M on day 3. DEC alone also had this effect at concentrations of 10(-6). 10(-5), and 10(-4) M on day 2. ALB alone did not have this effect throughout the experiment, at various concentrations. However, it had greater effect when used in combination with either DEC or IVM. The result also indicated that DEC or IVM, when used in combination with ALB at concentrations of 10(-6) M/10(-6) M, and 10(-5) M/10(-5) M was effectively better than each drug used alone at those concentrations. When both drug combinations were compared, ALB/DEC seemed to be more effective than ALB/IVM at a concentration of 10(-6) M/10(-6) M on day 3. Although IVM and DEC can reduce larval motility when used alone or in combination with ALB, they cannot kill these larvae in an in vitro cultivation, even at a high concentration (10(-5) M).

Effect of treatment with phenobarbital and stiripentol on carbamazepine-induced teratogenicity and reactive metabolite formation.

A model using SWV mice was developed to investigate the mechanistic basis of carbamazepine (CBZ)-related fetotoxicity. Drug administration was initiated prior to conception and continued until day 18 of gestation. The incidence of malformation was 33% following CBZ exposure (1,500 mg/kg/day), compared with a 5% incidence in pair-fed control animals (P < 0.05). Coadministration of nonteratogenic doses of phenobarbital (PB; a cytochrome P-450 inducer) (45 mg/kg/day) and CBZ (1,000 mg/kg/day) increased the frequency of malformation from 10% to 26% (P < 0.05), compared with mice dosed with CBZ alone (1,000 mg/kg/day). Coadministration of stiripentol (STP; a cytochrome P-450 inhibitor) (300 mg/kg/day) decreased the incidence of malformations produced by CBZ (1,500 mg/kg/day) from 33% to 16.7% (P < 0.05). The effect of PB administration on the binding of 14C in maternal and fetal tissue was assessed in dams that received CBZ (1,000 mg/kg/day) with or without PB (45 mg/kg/day) or STP (300 mg/kg/day) chronically and a single i.p. dose of 14C-CBZ on day 12 of gestation. In all instances, binding was greatest in maternal liver, then in the placenta, fetal head and body, and maternal thigh muscle. In all tissues, PB caused a two-to threefold increase in binding, compared with binding in mice exposed to CBZ alone. STP administration decreased protein adduct formation only in maternal liver. The binding of 14C was also assessed in hepatic microsomes prepared from female mice exposed to CBZ and PB or STP as in the in vivo study of 14C binding. The extent of irreversible binding was 67% greater in microsomes prepared from mice pretreated with PB and CBZ than with CBZ alone, while STP resulted in only 21% inhibition of 14C adduct formation (P < 0.05). The results are consistent with the formation of a chemically reactive teratogenic metabolite of CBZ in mice by cytochrome(s) P-450.

Studies on the acute lethality of diethylcarbamazine in the rat.

In spite of its effectiveness against microfilariae, very little is known about diethylcarbamazine's (DEC) therapeutic mechanism of action or the toxic sequelae which can result from overdose. In preliminary studies, a precipitous decrease in heart rate was noted in rats receiving 1000 mg DEC/kg ip. This effect was less pronounced at 750 mg/kg and was non-existent at 500 mg/kg. In the present study, attempts to attenuate DEC's cardiopulmonary insult by pretreating animals with cyproheptadine failed. Atropine pretreatment failed to block the negative chronotropic effects of DEC, but did restore respiratory function and reduce the lethality associated with the drug. Biochemical studies showed that ATP:ADP ratios in the hearts from rats given high dosages of DEC were elevated over those in controls (11:1 versus 5:1). Inosine levels decreased in cardiac tissues taken from DEC-treated rats. Subsequent enzyme studies revealed that DEC has a potent inhibitory effect on calcium-dependent ATPases from a variety of tissues. Taken together, our data indicate that the mode of acute DEC-lethality involves cardiopulmonary suppression. Furthermore, the cardiac depressant effect of DEC appears related to inhibition of calcium ATPases in cardiac myocytes. To our knowledge, this is the first report of ATPase sensitivity to DEC, a finding that has interesting toxicologic and pharmacologic ramifications.

Genotoxic potential of diethylcarbamazine, an antifilarial drug.

The mutagenic potential of diethylcarbamazine (DEC) was evaluated by metaphase chromosome analysis and the micronucleus test in bone marrow cells of mice. Both assay systems revealed clastogenicity, although not severe. The time-response study of metaphase chromosomes exhibited an early effect; at 72 h post-treatment the effect came down to the control level. The dose-response analysis showed significantly elevated frequencies of micronuclei (MN) for all the doses tested, but failed to show any influence of the dose on the induction of MN. Data on mitotic index (MI) indicated a lack of cell cycle inhibition. The decrease in aberration frequency with the lapse of time can be probably attributed to the elimination of the drug and its metabolites from the body.

Dirofilaria immitis: diethylcarbamazine-induced anaphylactoid reactions in infected dogs.

The immunopathogenesis of the anaphylactoid Mazzotti reactions has been studied by comparing physiologic and immunologic aspects of diethylcarbamazine-induced shock in Dirofilaria immitis infected dogs with antigen induced anaphylaxis in infected and uninfected controls. Filarial antigen, specific host IgG antibody, and C1 and C3 complement levels were quantitatively measured over time in relation to the levels of histamine and prostaglandin D2 in the blood and changes in mean blood pressure. D. immitis antigen injected into uninfected dogs having no detectable IgG antibody to D. immitis or Toxocara canis produced a rapid drop in blood pressure that paralleled a drop in C1 and C3 levels and an increase in prostaglandin D2. Antigen injected into infected dogs with IgG antibody produced a similar drop in blood pressure and complement and increase in prostaglandin D2 which differed from the uninfected group only in the slower clearance of antigen from the blood. Diethylcarbamazine alone produced no measurable changes in blood pressure or complement in uninfected hosts. Diethylcarbamazine, however, administered into skin test positive infected dogs, produced a temporally slower but quantitatively similar loss in blood pressure, drop in complement, and increase in prostaglandin D2 and histamine to that induced by antigen injection. Complement activation and immune complex formation are initiated by antigen release, and subsequent vasoactive mediator release leads to shock with prostaglandin D2 being quantitatively higher in blood than is histamine.