Activity of gatifloxacin alone or in combination with pyrimethamine or gamma interferon against Toxoplasma gondii

Surfactant vesicles for enhanced antitoxoplasmic effect of norfloxacin: in vitro and in vivo evaluations

The goal was to scrutinize niosomes as potential carriers for enhanced efficacy of norfloxacin against Toxoplasma gondii RH strain. This was assessed in vitro and in vivo. Standard niosomes of Span 60 and cholesterol were prepared. Gelucire 48/16 or Tween 80 was incorporated as hydrophilic fluidizer. The prepared vesicles were characterized for shape, size, viscosity and norfloxacin release. The in vitro anti-Toxoplasma was assessed by monitoring tachyzoites viability after incubation with niosomes. In vivo efficacy of niosomes encapsulated norfloxacin was evaluated on infected mice. Transmission electron micrographs showed nano-sized spherical vesicles. Norfloxacin release varied with niosomal composition to show faster liberation in presence of fluidizing agent. The half maximum effective concentration of norfloxacin against tachyzoites (EC50) was significantly reduced after niosomal encapsulation compared with simple drug solution with no significant difference between vesicular formulations. Tachyzoite count in the peritoneal fluid of infected mice was reduced by 45.2, 90.8, 88.3 and 84% after treatment with simple drug dispersion, standard niosomes, Gelucire containing and Tween containing vesicles, respectively compared to infected untreated mice. These results correlate with the in vitro data and reflects the efficacy of niosomes. The study introduced surfactant vesicles as a tool for enhanced efficacy of norfloxacin against toxoplasma.

Evaluation of anti-parasitic activities of new quinolones containing nitrofuran moiety against Toxoplasma gondii

Toxoplasmosis is a disease with a worldwide prevalence that is caused by Toxoplasma gondii. Pyrimethamine and sulfadiazine are two pharmacological agents commonly used to treat of this infection. However, they are accompanied by some side effects. Therefore, the identifying of new drugs with low toxocytosis seems to be a matter of vital importance. Quinolones are DNA replication inhibitors, exerting inhibitory effects against many pathogens, including bacteria, mycoplasma, and protozoa. Given the importance of quinolones and their efficacy, the present in vitro study was conducted to investigate the antiparasitic activities of new quinolones (NFQ-2, NFQ-5, and NFQ-6) containing nitrofuran moiety against T. gondii. To this end, Vero cells were incubated with various concentrations of new quinolones and pyrimethamine (positive control) to determine their viability. Subsequently, they were infected with T. gondii (RH strain) and then subjected to drug treatment. The obtained IC₅₀ values were 3.60, 4.84, 5.59, 3.44 and 2.75 μg/mL for NFQ-2, NFQ-5, NFQ-6, ciprofloxacin and pyrimethamine, respectively. The CC₅₀ values for the NFQ-2, NFQ-5, and NFQ-6 were 25.20, 29.89, and 28.43 μg/mL, indicating the selectivity indexes more than 5 for these compounds. The anti-Toxoplasma efficiency was determined by evaluating infection index, number and size of plaques, and T. gondii intracellular proliferation. As the results indicated, the administration of new quinolone derivatives resulted in the reduction of intracellular proliferation, infection index, and the number and size of plaques in comparison to uninfected treated cells (P < 0.05). The results were indicative of a considerable synergetic effect when each of the derivatives was used in combination with pyrimethamine, compared to when used alone. Based on our results, the nitrofuran-derived quinolones can be considered as new leads for the design of new anti-Toxoplasma agents.

Toxoplasmosis: Current and Emerging Parasite Druggable Targets

Toxoplasmosis is a prevalent disease affecting a wide range of hosts including approximately one-third of the human population. It is caused by the sporozoan parasite Toxoplasma gondii (T. gondii), which instigates a range of symptoms, manifesting as acute and chronic forms and varying from ocular to deleterious congenital or neuro-toxoplasmosis. Toxoplasmosis may cause serious health problems in fetuses, newborns, and immunocompromised patients. Recently, associations between toxoplasmosis and various neuropathies and different types of cancer were documented. In the veterinary sector, toxoplasmosis results in recurring abortions, leading to significant economic losses. Treatment of toxoplasmosis remains intricate and encompasses general antiparasitic and antibacterial drugs. The efficacy of these drugs is hindered by intolerance, side effects, and emergence of parasite resistance. Furthermore, all currently used drugs in the clinic target acute toxoplasmosis, with no or little effect on the chronic form. In this review, we will provide a comprehensive overview on the currently used and emergent drugs and their respective parasitic targets to combat toxoplasmosis. We will also abridge the repurposing of certain drugs, their targets, and highlight future druggable targets to enhance the therapeutic efficacy against toxoplasmosis, hence lessening its burden and potentially alleviating the complications of its associated diseases.

Anti-Toxoplasma gondii activity of 5-oxo-hexahydroquinoline derivatives: synthesis, in vitro and in vivo evaluations, and molecular docking analysis

BACKGROUND AND PURPOSE

The aim of this study was to evaluate the in vitro and in vivo anti-Toxoplasma gondii (T. gondii) effect of 5-oxo-hexahydroquinoline compounds. Moreover, molecular docking study of the compounds into the active site of enoyl-acyl carrier protein reductase (ENR) as a necessary enzyme for the vitality of apicoplast was carried out.

EXPERIMENTAL APPROACH

A number of 5-oxo-hexahydoquinoline derivatives (Z1-Z4) were synthesized. The T. gondii tachyzoites of RH strain were treated by different concentrations (1-64 μg/mL) of the compounds. The viability of the encountered parasites with compounds was assessed using flow cytometry and propidium iodide (PI) staining. Due to the high mortality effect of Z3 and Z4 in vitro, their chemotherapy effect was assessed by inoculation of tachyzoites to four BALB/c mice groups (n = 5), followed by the gavage of various concentrations of the compounds to the mice. Molecular docking was done to study the binding affinity of the synthesized 5-oxo-hexahydroquinolines into ENR enzyme active site byusing AutoDock Vina® software. Docking was performed by a Lamarckian Genetic Algorithm with 100 runs.

FINDINGS / RESULTS

Flow cytometry assay results indicated compounds Z3 and Z4 had relevant mortality effect on parasite tachyzoites. Besides, in vivo experiments were also performed and a partial increase of mice longevity between control and experiment groups was recorded. Molecular docking of Z3 and Z4 in the binding site of ENR enzyme indicated that the compounds were well accommodated within the binding site. Therefore, it could be suggested that these compounds may exert their anti-T. gondii activity through the inhibition of the ENR enzyme.

CONCLUSION AND IMPLICATIONS

Compounds Z3 and Z4 are good leads in order to develop better anti-T. gondii agents as they demonstrated both in vitro and in vivo inhibitory effects on tachyzoites viability and infection. Further studies on altering the route of administration along with additional pharmacokinetics evaluations are needed to improve the anti-T. gondii impacts of 5-oxo-hexahydroquinoline compounds.

Inhibitory effects of novel ciprofloxacin derivatives on the growth of four Babesia species and Theileria equi

The problems of parasite resistance, as well as the toxic residues to most of the commercially available antipiroplasmic drugs severely weaken their effective, curative, and environmental safe employment. Therefore, it is clear that the development of treatment options for piroplasmosis is vital for improving disease treatment and control. Ciprofloxacin is a broad-spectrum antibiotic that targets mainly the DNA replication machinery by inhibiting DNA gyrase and topoisomerase enzymes. As a result, ciprofloxacin is used for treating several bacterial and parasitic infections. In this study, the efficacy of 15 novel ciprofloxacin derivatives (NCD) that had been developed against drug-resistant Mycobacterium tuberculosis was evaluated against piroplasm parasite multiplication in vitro. The half-maximal inhibitory concentration (IC₅₀) values of the most effective five compounds of NCD (No. 3, 5, 10, 14, 15) on Babesia bovis, Babesia bigemina, Babesia caballi, and Theileria equi were 32.9, 13.7, 14.9, and 30.9; 14.9, 25.8, 13.6, and 27.5; 34.9, 33.9, 21.1, and 22.3; 26.7, 28.3, 34.5, and 29.1; and 4.7, 26.6, 33.9, and 29.1 μM, respectively. Possible detrimental effects of tested NCD on host cells were assessed using mouse embryonic fibroblast (NIH/3T3) and Madin-Darby bovine kidney (MDBK) cell lines. Tested NCD did not suppress NIH/3T3 and MDBK cell viability, even at the highest concentration used (500 μM). Combination treatments of the identified most effective compounds of NCD/diminazene aceturate (DA), /atovaquone (AQ), and /clofazimine (CF) showed mainly synergistic and additive effects. The IC₅₀ values of NCD showed that they are promising future candidates against piroplasmosis. Further in vivo trials are required to evaluate the therapeutic potential of NCD.

Emerging Therapeutic Targets Against Toxoplasma gondii: Update on DNA Repair Response Inhibitors and Genotoxic Drugs

Toxoplasma gondii is the causative agent of toxoplasmosis in animals and humans. This infection is transmitted to humans through oocysts released in the feces of the felines into the environment or by ingestion of undercooked meat. This implies that toxoplasmosis is a zoonotic disease and T. gondii is a foodborne pathogen. In addition, chronic toxoplasmosis in goats and sheep is the cause of recurrent abortions with economic losses in the sector. It is also a health problem in pets such as cats and dogs. Although there are therapies against this infection in its acute stage, they are not able to permanently eliminate the parasite and sometimes they are not well tolerated. To develop better, safer drugs, we need to elucidate key aspects of the biology of T. gondii. In this review, we will discuss the importance of the homologous recombination repair (HRR) pathway in the parasite's lytic cycle and how components of these processes can be potential molecular targets for new drug development programs. In that sense, the effect of different DNA damage agents or HHR inhibitors on the growth and replication of T. gondii will be described. Multitarget drugs that were either associated with other targets or were part of general screenings are included in the list, providing a thorough revision of the drugs that can be tested in other scenarios.

Interaction of apigenin-7-O-glucoside with pyrimethamine against Toxoplasma gondii growth

Apigenin-7-O-glucoside, a flavonoid glucoside known to inhibit cancer cell growth, fungi growth, both intra and extracellular reactive oxygen species generation, causing cell arrest and damage to the plasma membrane, was tested alone or in combination with a dihydrofolate inhibitor (pyrimethamine) against Toxoplasma gondii (T. gondii) growth. The anti-T. gondii activity was carried out using a high throughput antiparasitic drug screening cell-based assay known as 2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H tetrazolium, monosodium salt (WST-8) and fluorescence plate reader. The 50% effective concentration inhibition and 95% confidence interval values for individual and combination treatments against T. gondii were 0.80 (0.38-1.29) µg/mL, 1.05 (0.275-2.029) µg/mL, and 0.40 (0-1.06) µg/mL for apigenin-7-O-glucoside, pyrimethamine, and apigenin-7-O-glucoside plus pyrimethamine, respectively. Interestingly, the apigenin-7-O-glucoside plus pyrimethamine combination showed an additive inhibition effect against T. gondii growth in vitro using the fractional inhibitory concentration index method. It was discovered that the apigenin-7-O-glucoside combination with pyrimethamine had a high selectivity index 62.5, which implies 62-fold inhibition activity against the parasite versus human foreskin fibroblast cell cytotoxicity. This new combination hit is novel and will have the potential for future effective, safe, and less costly anti-Toxoplasma drug development, if its in vivo activity shows similar findings.

Interactions of a prenylated flavonoid from Dalea elegans with fluconazole against azole- resistant Candida albicans

BACKGROUND

The prenylated flavonoid 2', 4'-dihydroxy-5'-(1'″, 1'″-dimethylallyl)-8-prenylpinocembrin (8PP, formerly 6PP) shows antifungal activity, inhibits rhodamine 6G efflux and reverses fluconazole (FCZ) resistance in azole-resistant Candida albicans overexpressing cdr1, cdr2 and mdr1 transporters.

PURPOSE AND DESIGN

In this paper, we tried to characterize 8PP in vitro interactions on the cell growth and lethality of C. albicans. We also initiated preliminary in vivo toxicological studies on mice.

METHODS

The effects of 8PP and FCZ on cell growth and viability of C. albicans were evaluated by CLSI guidelines. The checkerboard assay was used to search for interactions on cell growth. The time-kill assay was used to study fungicidal effects. Acute toxicity was evaluated at a single dose schedules.

RESULTS

From the checkerboard design, and using a starting inoculum of 10³CFU/ml, the fractional inhibitory concentration (FIC) of FCZ and 8PP could be determined as 0.11 and 0.50, respectively, with a FIC index value (FICI) of 0.61. This FICI and the isobologram showing a concave shape suggests an additive interaction between them. At a higher starting inoculum (10⁵CFU/ml), C. albicans growth and viability were decreased by FCZ, 8PP and their combination in a concentration-dependent way. For FCZ, minimum fungicidal concentration (MFC) and FC₅₀ (the concentration that kills 50% of the fungal cells) were 4-fold reduced (280-70µM) in combination with 125µM 8PP. A decrease of 3 log units in viable counts with respect to control was reached (3.65 ± 1.05 ‰, p< 0.0001). Thus, both fungistatic compounds when combined achieved an almost complete fungicidal effect at lower concentrations respecting of each of them alone. In preliminary toxicological assessment, lethal dose 50% (LD₅₀) for 8PP by the i.p. route was 357 and 245mg/kg, for female and male adult albino mice, respectively. FCZ LD₅₀ was 785 and 650mg/kg for female and male animals, respectively CONCLUSIONS: In vitro results suggest additive interactions between 8PP and FCZ with respect to C. albicans cell growth. Besides killing per se, 8PP helps FCZ to achieve an almost complete fungicidal effect, which would be crucial to eradicate fungal infections.

Enrofloxacin and Toltrazuril Are Able to Reduce Toxoplasma gondii Growth in Human BeWo Trophoblastic Cells and Villous Explants from Human Third Trimester Pregnancy

Classical treatment for congenital toxoplasmosis is based on combination of sulfadiazine and pyrimethamine plus folinic acid. Due to teratogenic effects and bone marrow suppression caused by pyrimethamine, the establishment of new therapeutic strategies is indispensable to minimize the side effects and improve the control of infection. Previous studies demonstrated that enrofloxacin and toltrazuril reduced the incidence of Neospora caninum and Toxoplasma gondii infection. The aim of the present study was to evaluate the efficacy of enrofloxacin and toltrazuril in the control of T. gondii infection in human trophoblast cells (BeWo line) and in human villous explants from the third trimester. BeWo cells and villous were treated with several concentrations of enrofloxacin, toltrazuril, sulfadiazine, pyrimethamine, or combination of sulfadiazine+pyrimethamine, and the cellular or tissue viability was verified. Next, BeWo cells were infected by T. gondii (2F1 clone or the ME49 strain), whereas villous samples were only infected by the 2F1 clone. Then, infected cells and villous were treated with all antibiotics and the T. gondii intracellular proliferation as well as the cytokine production were analyzed. Finally, we evaluated the direct effect of enrofloxacin and toltrazuril in tachyzoites to verify possible changes in parasite structure. Enrofloxacin and toltrazuril did not decrease the viability of cells and villous in lower concentrations. Both drugs were able to significantly reduce the parasite intracellular proliferation in BeWo cells and villous explants when compared to untreated conditions. Regardless of the T. gondii strain, BeWo cells infected and treated with enrofloxacin or toltrazuril induced high levels of IL-6 and MIF. In villous explants, enrofloxacin induced high MIF production. Finally, the drugs increased the number of unviable parasites and triggered damage to tachyzoite structure. Taken together, it can be concluded that enrofloxacin and toltrazuril are able to control T. gondii infection in BeWo cells and villous explants, probably by a direct action on the host cells and parasites, which leads to modifications of cytokine release and tachyzoite structure.

Host and Toxoplasma gondii genetic and non-genetic factors influencing the development of ocular toxoplasmosis: A systematic review

Toxoplasmosis is a cosmopolitan infection caused by the apicomplexan parasite Toxoplasma gondii. This infectious disease is widely distributed across the world where cats play an important role in its spread. The symptomatology caused by this parasite is diverse but the ocular affectation emerges as the most important clinical phenotype. Therefore, we conducted a systematic review of the current knowledge of ocular toxoplasmosis from the genetic diversity of the pathogen towards the treatment available for this infection. This review represents an update to the scientific community regarding the genetic diversity of the parasite, the genetic factors of the host, the molecular pathogenesis and its association with disease, the available diagnostic tools and the available treatment of patients undergoing ocular toxoplamosis. This review will be an update for the scientific community in order to encourage researchers to deploy cutting-edge investigation across this field.

Clinically Available Medicines Demonstrating Anti-Toxoplasma Activity

Toxoplasma gondii is an apicomplexan parasite of humans and other mammals, including livestock and companion animals. While chemotherapeutic regimens, including pyrimethamine and sulfadiazine regimens, ameliorate acute or recrudescent disease such as toxoplasmic encephalitis or ocular toxoplasmosis, these drugs are often toxic to the host. Moreover, no approved options are available to treat infected women who are pregnant. Lastly, no drug regimen has shown the ability to eradicate the chronic stage of infection, which is characterized by chemoresistant intracellular cysts that persist for the life of the host. In an effort to promote additional chemotherapeutic options, we now evaluate clinically available drugs that have shown efficacy in disease models but which lack clinical case reports. Ideally, less-toxic treatments for the acute disease can be identified and developed, with an additional goal of cyst clearance from human and animal hosts.

In Vivo Efficacy of Drugs against Toxoplasma gondii Combined with Immunomodulators

The aim of this study is to evaluate the effects of pyrimethamine (PYR) and sulfadiazine (SDZ) combined with levamisole and echinacea on the survival of mice infected with Toxoplasma gondii. For this, we used 99 specific pathogen-free BALB/c mice. All the mice were infected intraperitoneally with 10(5) T. gondii tachyzoites and were divided into 11 groups, each including 9 mice. Except for the control group, oral treatment was initiated in all groups 24 h post infection and was continued for 10 days. The treatment regimen included dual combinations of PYR (dose, 6.25 and 12.5 mg/kg/day) and SDZ (dose, 100 and 200 mg/kg/day), triple combinations of PYR + SDZ, and levamisole (dose, 2.5 mg/kg/day) or echinacea (dose, 130 and 260 mg/kg/day) and echinacea alone (dose, 130 and 260 mg/kg/day). We observed that an effective dose of the combination of PYR + SDZ and levamisole resulted in a statistically significant increase in the survival rate from 33.3% to 88.9%. Similarly, half the dose of this combination resulted an increase in the survival rate from 0% to 44.4% (p < 0.05). Survival rate also increased in the groups treated with the combinations including echinacea; however, the difference did not reach statistical significance. The triple combination of PYR-SDZ-levamisole could be an alternative treatment option in case of infections caused by T. gondii.

Ciprofloxacin Derivatives Affect Parasite Cell Division and Increase the Survival of Mice Infected with Toxoplasma gondii

Toxoplasmosis, caused by the protozoan Toxoplasma gondii, is a worldwide disease whose clinical manifestations include encephalitis and congenital malformations in newborns. Previously, we described the synthesis of new ethyl-ester derivatives of the antibiotic ciprofloxacin with ~40-fold increased activity against T. gondii in vitro, compared with the original compound. Cipro derivatives are expected to target the parasite's DNA gyrase complex in the apicoplast. The activity of these compounds in vivo, as well as their mode of action, remained thus far uncharacterized. Here, we examined the activity of the Cipro derivatives in vivo, in a model of acute murine toxoplasmosis. In addition, we investigated the cellular effects T. gondii tachyzoites in vitro, by immunofluorescence and transmission electron microscopy (TEM). When compared with Cipro treatment, 7-day treatments with Cipro derivatives increased mouse survival significantly, with 13-25% of mice surviving for up to 60 days post-infection (vs. complete lethality 10 days post-infection, with Cipro treatment). Light microscopy examination early (6 and 24h) post-infection revealed that 6-h treatments with Cipro derivatives inhibited the initial event of parasite cell division inside host cells, in an irreversible manner. By TEM and immunofluorescence, the main cellular effects observed after treatment with Cipro derivatives and Cipro were cell scission inhibition--with the appearance of 'tethered' parasites--malformation of the inner membrane complex, and apicoplast enlargement and missegregation. Interestingly, tethered daughter cells resulting from Cipro derivatives, and also Cipro, treatment did not show MORN1 cap or centrocone localization. The biological activity of Cipro derivatives against C. parvum, an apicomplexan species that lacks the apicoplast, is, approximately, 50 fold lower than that in T. gondii tachyzoites, supporting that these compounds targets the apicoplast. Our results show that Cipro derivatives improved the survival of mice acutely infected with T. gondii and inhibited parasite replication early in the first cycle of infection in vitro, highlighting their therapeutic potential for the treatment of toxoplasmosis.

Great efficacy of sulfachloropyrazine-sodium against acute murine toxoplasmosis

OBJECTIVE

To identify more effective and less toxic drugs to treat animal toxoplasmosis.

METHODS

Efficacy of seven kinds of sulfonamides against Toxoplasma gondii (T. gondii) in an acute murine model was evaluated. The mice used throughout the study were randomly assigned to many groups (10 mice each), which either remained uninfected or were infected intraperitoneally with tachyzoites of T. gondii (strains RH and CN). All groups were then treated with different sulfonamides and the optimal treatment protocol was determined candidates. Sulfadiazine-sodium (SD) was used for comparison.

RESULTS

The optimal therapy involved gavaging mice twice per day with 250 mg/kg bw of sulfachloropyrazine-sodium (SPZ) for five days. Using this protocol, the average survival time and the time-point of 50% fatalities were prolonged significantly compared with SD treatment. Treatment with SPZ protected 40% of mice from death, and the heart and kidney tissue of these animals was parasite-free, as determined by nested-PCR. SPZ showed excellent therapeutic effects in the treatment of T. gondii in an acute murine model and is therefore a promising drug candidate for the treatment and prevention of T. gondii in animals.

CONCLUSIONS

It can be concluded that the effective drug sulfachloropyrazine may be the new therapeutic options against animal toxoplasmosis.

Gatifloxacin induces S and G2-phase cell cycle arrest in pancreatic cancer cells via p21/p27/p53

Pancreatic cancer, despite being the most dreadful among gastrointestinal cancers, is poorly diagnosed, and further, the situation has been aggravated owing to acquired drug resistance against the single known drug therapy. While previous studies have highlighted the growth inhibitory effects of older generation fluoroquinolones, the current study aims to evaluate the growth inhibitory effects of newer generation fluoroquinolone, Gatifloxacin, on pancreatic cancer cell lines MIA PaCa-2 and Panc-1 as well as to elucidate the underlying molecular mechanisms. Herein, we report that Gatifloxacin suppresses the proliferation of MIA PaCa-2 and Panc-1 cells by causing S and G₂-phase cell cycle arrest without induction of apoptosis. Blockade in S-phase of the cell cycle was associated with increased TGF-β1 expression and translocation of Smad3-4 complex to the nucleus with subsequent activation of p21 in MIA PaCa-2 cells, whereas TGF-β signalling attenuated Panc-1 cells showed S-phase arrest by direct activation of p27. However, Gatifloxacin mediated G₂–phase cell cycle arrest was found to be p53 dependent in both the cell lines. Our study is of interest because fluoroquinolones have the ability to penetrate pancreatic tissue which can be very effective in combating pancreatic cancers that are usually associated with loss or downregulation of CDK inhibitors p21/p27 as well as mutational inactivation of p53. Additionally, Gatifloxacin was also found to synergize the effect of Gemcitabine, the only known drug against pancreatic cancer, as well as the broad spectrum anticancer drug cisplatin. Taken together our results suggest that Gatifloxacin possesses anticancer activities against pancreatic cancer and is a promising candidate to be repositioned from broad spectrum antibiotics to anticancer agent.

Heat stress-induced modulation of host defense against Toxoplasma gondii infection in mice

This study examined the effects of burn injury on murine immune response against Toxoplasma gondii infection. Male C57BL/6 mice were divided into 3 groups: T. gondii infection (group T), burn injury (group B), and burn injury followed by T. gondii infection (group BT). The survival of group BT was significantly lower than those of group B and group T. Parasite abundance in the tissues was determined by quantitative competitive-polymerase chain reaction. Group BT exhibited significantly higher numbers of T. gondii than group T. Antibody production against T.g.HSP30 in group BT was significantly lower than that in group T, whereas no significant difference was observed in SAG1-specific antibody production. Delayed-type hypersensitivity (DTH) specific for 2,4-dinitrofluorobenzene (DNFB) of both group B and group BT was significantly lower than that of group T. One week after infection, serum interferon-gamma (IFN-gamma) and interleukin (IL)-10 levels in group BT were significantly lower, whereas serum IL-6 levels were significantly higher than in group T Serum TNF-alpha levels in both group T and group BT were elevated at 1 wk after infection, although there was no significant difference between them. Serum IFN-gamma, IL-10, and TNF-alpha levels in group B were not elevated during the experimental term. In conclusion, the impaired antigen-specific antibody production and DTH response, together with the modulated patterns of cytokine responses, seemed to be strongly involved in the development of burn-induced immunosuppression and the consequent increased susceptibility to T. gondii infection in mice.

Population pharmacokinetics of pyrimethamine and sulfadoxine in children treated for congenital toxoplasmosis

The population pharmacokinetics of pyrimethamine (PYR) and sulfadoxine (SDX) for a group of 32 children with congenital toxoplasmosis was investigated by nonparametric modeling analysis. A one-compartment model was used as the structural model, and individual pharmacokinetic parameters were estimated by Bayesian modeling. PYR (1.25 mg/kg of body weight) and SDX (25 mg/kg) were administered orally every 10 days for 1 year, with adjustment of the dose to body weight every 3 months. Drug concentrations were measured by high-performance liquid chromatography. A total of 101 measurements in serum were available for both drugs. Mean absorption rate constants, volumes of distribution, elimination rate constants, and half-lives were 0.915 h(-1), 4.379 liters/kg, 0.00839 h(-1), and 5.5 days for PYR and 1.659 h(-1), 0.392 liters/kg, 0.00526 h(-1), and 6.6 days for SDX, respectively. Wide interindividual variability was observed. The estimated minimum and maximum concentrations of PYR in serum differed 8- and 25-fold among patients, respectively, and those of SDX differed 4- and 5-fold, respectively. Increases in the concentration of PYR were observed for eight children, and increases in the SDX concentration were observed for seven children. Serum PYR-SDX concentrations are unpredictable even when the dose is standardized for body weight. The concentrations of the PYR-SDX combination that are most efficacious for children have not yet been established. A model such as ours, associated with long-term follow-up, is needed to study the correlation between exposure to these two drugs and clinical outcome in children.