Magnetic molecularly imprinted conducting polymer for determination of praziquantel enantiomers in milk.

A new selective adsorbent based on magnetic molecularly imprinted conducting polymer was firstly synthetized and applied to the magnetic solid phase extraction (MSPE) for the determination of PZQ enantiomers in milk samples. The enantioselective separation was performed on a Chiralpak® IB column using mobile phase composed of ultrapure water : tetrahydrofuran : diethylamine (65 : 35 : 0.05, v/v/v). After MSPE optimization, in which a magnetic molecularly imprinted polypyrrole (MMIPPy) was used as adsorbent, the best conditions were: 500 µL of acetonitrile as eluent, 75 mg of MMPPy, 1000 µL of milk sample (pH adjusted to 6.5.). The analyses showed recoveries/relative standard deviation (RSD%) 79.7 ± 2.5 and 81.1 ± 2.2 for (R)-(-)-PZQ and (S)-(+)-PZQ, respectively. By computational study carried out on the molecular design of the synthesized MMIPPy, it was found that the formation of four hydrogen bonds and one π-π stacking interaction explain the formation of the PZQ-pyrrole pre-polymerization complex at the molecular level. From the analytical validation, the developed method showed to be linear in the concentration range of 0.01 to 10 µg mL-1, with correlation coefficient larger than 0.98 and RSD% values below 15%. The LOQ obtained was 0.01 µg mL-1 for both enantiomers, with RSD% and relative error below 20%. The method was successfully applied in real sheep milk samples from various local suppliers. Finally, the results showed that MMIPPy in MSPE is an economical, simple and easy-to-perform technique.

Validated capillary electrophoretic method for the enantiomeric quality control of R-praziquantel.

The enantiomers of praziquantel, the drug of choice in schistosomiasis, were separated by electrokinetic chromatography with cyclodextrins. Nine anionic cyclodextrins were screened for their ability to discriminate between the uncharged enantiomers. Seven investigated selectors presented chiral interactions with the enantiomers, these cases being interpreted in terms of stability constants and complex mobilities. The best results were delivered by sulfated-ß-cyclodextrin, where quasi-equal stability constants were accompanied by extreme selectivity values and was explained on the basis of highly different mobilities of the transient diastereomeric complexes. Since the enantiomer migration order was unfavorable, a simple polarity switch was employed (detection end at anode), which apart from migration order reversal, also resulted in extreme resolution values (Rs > 35) and increased migration times. After optimization (50 mM phosphate buffer pH 2.0, supplied with 15 mM sulfated-ß-cyclodextrin, 15 kV, capillary temperature 25°C, short-end injection with 50 mbar × 2 s), analysis time under 10 min were obtained, while still maintaining high resolution (Rs > 10). The method was validated according to the ICH guidelines and application of the method was tested on in-house synthetized R-praziquantel batches and on commercial, combination tablets containing racemic mixture of the drug.

Solid-state electrochemical assay of heme-binding molecules for screening of drugs with antimalarial potential.

The interaction between heme and ligands is the basis for a variety of tests aimed at the discovery of antiplasmodial molecules. Two electrochemical methods for the screening of molecules with potential antimalarial activity through heme-binding mechanism are described. The first method is applicable to lipophilic environment, by using solution phase electrochemistry in DMSO solutions of Fe(III)-heme plus the tested compounds at carbon electrodes. This method provides well-defined voltammetric signals, characteristic of the heme-ligand (L) interaction. The second method involves aqueous media at biological pH and the use of voltammetry of immobilized particles, by means of microparticulate films of the tested compounds immersed into Fe(III)-heme solutions with no need of prior incubation. These methodologies are applied to the testing of heme-binding activity in macromolecular level systems like hemoglobin, or much more complex mixtures like total blood, erythrocytes, or hemolyzed samples.

Determination of active substances in binary mixture antiparasitic veterinary formulations by HPLC.

The purpose of the study was to develop a simple, versatile HPLC method for the identification and quantification of praziquantel and ivermectin (in Equimax) or praziquantel and abamectin (in Abamitel Plus). A satisfactory separation was obtained using the Supelcosil LC-ABZ+ column in gradient system with a mobile phase A: acetonitrile / water in 40:60 ratio and phase B: acetonitrile. The UV detection was set at 245 nm. The correlation coefficient values (> or = 0,998) for all active substances confirmed that the calibration curves (peak area vs. concentration) are linear. The results of the quantification and the statistical evaluation confirmed that the method is accurate and precise. It can also be applied to confirm the identity of benzyl alcohol, methyl p-hydroxybenzoate and propyl p-hydroxybenzoate in Abamitel Plus formulation.

Investigation on the uptake of ciprofloxacin, chloramphenicol and praziquantel by button mushrooms.

Button mushrooms are widely produced edible basidiomycetes. Commercially, they are cultivated on substrates containing fermented horse manure and chicken feces. Since pharmacologically active substances (PAS) might be introduced into the food chain via animal treatment, their residues may be present in manure used for mushroom growth. Previous studies in plants have demonstrated an uptake of PAS from the agricultural environment. The present study was performed to investigate the presence of PAS in button mushrooms. For analysis, a multi-analyte method for the detection of 21 selected PAS using liquid chromatography tandem-mass spectrometry was developed, successfully validated and applied to commercially available button mushrooms. Traces of chloramphenicol were detected in two of 20 samples. Additionally, in a mushroom cultivation experiment an uptake of ciprofloxacin, chloramphenicol and praziquantel was conducted. Throughout the whole experiment, praziquantel was present in quantifiable amounts in mushrooms and in high quantities in soil.

Identification of degradation products of praziquantel during the mechanochemical activation.

Praziquantel (PZQ) is an inexpensive, low toxicity BCS II class anthelmintic drug used for the treatment of neglected tropical diseases. In earlier papers a mechanochemical activation has been used to induce physical transformations on the drug which would ameliorate its solubility and hence its bioavailability and a systematic study of the effects of varying temperature, frequency and time of milling on drug melting enthalpy and drug recovery was given. In this communication, the focus is on the degradation products that are formed during this mechanical treatment of Praziquantel. In the cogrinding process with povidone and crospovidone several degradation products are formed. Different degradation products are formed, which depend on the type of polymer rather than the process conditions. Two of the most prominent degradation products were identified and their structure proposed on the basis of information obtained from GC-MS, UPLC-MS and 1H NMR techniques.

Accuracy of the WHO praziquantel dose pole for large-scale community treatment of urogenital schistosomiasis in northern Mozambique: Is it time for an update?

BACKGROUND: A pioneering strategy developed by the World Health Organization (WHO) for the control of schistosomiasis was the concept of a height-based dose pole to determine praziquantel (PZQ) dosing in large-scale treatment campaigns. However, some recent studies have shown variable accuracy for the dose pole in terms of predicting correct mg/Kg dosing, particularly for treatment of adults. According to the WHO, 91 million adults in 52 countries are targeted to be treated by 2020. METHODS/PRINCIPAL FINDINGS: The present study aimed to test the accuracy of the dose pole in determining PZQ dosage by comparing the number of tablets determined by the dose pole with the number of tablets determined according to total body weight. The analysis included height-for-weight data from 9,827 school-aged children (SAC) and adults from 42 villages in the province of Cabo Delgado in Mozambique. The results revealed that of the 7,596 SAC, 91.8% has received an appropriate dose (30-60mg/Kg), 6% received an insufficient dose (<30mg/Kg) and 2% an excessive dose (> 60mg/Kg). On the other hand, 13.7% out of 2,231 adults were treated inaccurately with 13.5% receiving an insufficient dose and 0.2% an excessive dose. When the percentage of insufficient dosing was disaggregated by gender, the frequency of adult females who were underdosed reached 18.3% versus 10.8% of adult males. Of note, Adult females aged 21-55 years were found to have an underdose frequency of 21.3%, compared to 11.8% of adult males in the same age range. The performance of a proposed modified dose pole was compared using the same dataset of adult Mozambicans. The results showed that the modified dose pole reduced the underdose frequency among adults from 13.5% to 10.4%, and subsequently increased the percentage of optimal dosing from 33.7% to 45.3%. CONCLUSIONS: Our findings highlight the need to update the WHO-dose pole to avoid administration of insufficient PZQ doses to adults and therefore minimize the potential emergence of PZQ-resistant strains. TRIAL REGISTRATION: International Standard Randomized Controlled Trial registry under ISRTC number 14117624.

High Efficacy of Praziquantel in Schistosoma haematobium-Infected Children in Taraba State, Northeast Nigeria: A follow-up study.

OBJECTIVES: This study aimed to assess the efficacy of praziquantel in reducing urinary schistosomiasis prevalence, parasite burden and morbidity rates among a previously reported sample of Schistosoma haematobium-infected children. In addition, predisposing factors for reinfection one year post-treatment were also determined. METHODS: This prospective follow-up study was conducted between March 2014 and February 2015 among 675 previously reported children with urinary schistosomiasis in the Murbai and Surbai communities of Ardo Kola, Taraba State, Nigeria. A single dose of 40 mg/kg of praziquantel was administered to each infected child, with a second dose administered one month later if necessary. The number of S. haematobium eggs in urine samples was calculated at baseline and post-treatment. RESULTS: At four weeks post-treatment, the overall cure rate was 98.1%. Among children with low and heavy parasite burdens at baseline, egg reduction rates (ERRs) were 100% and 96.5%, respectively. The vast majority of children with microhaematuria (98.7%) and proteinuria (98.6%) at baseline were cured at follow-up. Following a second dose, the ERR, overall and morbidity cure rates increased to 100%. At one year post-treatment, 272 infected children (40.3%) were re-assessed; of these, 51 children (18.8%) were reinfected. Close proximity to bodies of water (odds ratio [OR] = 1.23, 95% confidence interval [CI]: 0.998-1.530; P = 0.05) and fishing (OR = 2.23, 95% CI: 0.828-6.040; P = 0.01) were significant factors that predisposed children to reinfection. CONCLUSION: A moderate rate of reinfection was noted. Governmental and nongovernmental organisations in Nigeria should collaborate on mass treatment and health education campaigns to reduce the incidence of urinary schistosomiasis reinfections.

Evaluation of a novel micro-sampling device, Mitra™, in comparison to dried blood spots, for analysis of praziquantel in Schistosoma haematobium-infected children in rural Côte d'Ivoire.

Pharmacokinetic (PK) studies with paediatric populations are increasing in importance for drug development. However, conventional PK sampling methods are characterised by invasiveness and low patient adherence, unsuitable for use with sensitive population, such as children. Mitra™ is a novel volumetric absorptive micro-sampling device, which offers an alternative to the dried blood spotting (DBS) technique, a current popular sampling technique within PK studies. We tested Mitra™ for the first time in the framework of a randomised controlled trial in rural Côte d'Ivoire. Thirty-five school-aged children, infected with Schistosoma haematobium, were sampled with both DBS and Mitra™, at 10 time points after treatment with praziquantel (PZQ). An extraction method for PZQ from Mitra™ was developed, optimised and validated. Analytes, namely R- and S-praziquantel (R-/SPZQ) and the main human metabolite, R-trans-4-OH-praziquantel, were measured using liquid chromatography-tandem mass spectrometry and the results were compared with Bland-Altman analysis to determine agreement between matrices. PK parameters, such as maximal plasma concentration and area under the concentration-time curve, were estimated using non-compartmental analysis. While we observed strong positive correlation (R2 > 0.98) and agreement between both matrices within the calibration line and quality control samples, Mitra™ revealed higher concentrations of all the analytes in the majority of patients' samples compared to DBS sampling, namely 63% samples for RPZQ, 49% for SPZQ and 78% for the metabolite were overestimated. While T1/2 and Tmax were in agreement between both matrices, area under the curve and maximal blood concentration were up to 2× higher for Mitra™ samples, with P < 0.005 for all parameters except Cmax of SPZQ, which was not significantly different between the two matrices. The reasons for the higher PZQ concentrations, more pronounced in incurred Mitra™ samples compared to spiked samples, are yet to be fully explored. Mitra™ appears superior to DBS in terms of simplicity and practicality however labelling issues and the high price of Mitra™ are difficult to overlook.

A high-performance liquid chromatography and nuclear magnetic resonance spectroscopy-based analysis of commercially available praziquantel tablets.

The amount of active ingredient in 20 commercially sourced batches of praziquantel (PZQ) tablets was determined using a high-performance liquid chromatography-ultraviolet (HPLC-UV) assay in conjunction with an anthentic, lot of PZQ powder. The general composition of each batch of tablets was also examined by means of (1)H nuclear magnetic resonance (NMR) spectroscopy and the NMR data were subjected to pattern recognition analysis by means of principal component analysis. The HPLC-UV results showed that each batch of PZQ tablets contained approximately the required amount of PZQ (600 mg per tablet). The NMR analysis showed a high degree of compositional variation between manufacturers, which caused by variation in excipients, along with some batch-to-batch variation in the tablets from a single manufacturer. Additionally, the PZQ tablets from one manufacturer were found to have an extra component (methyl-4-hydroxybenzoate) that was not detected in the other preparations.

A quantification method for determination of racemate praziquantel and R-enantiomer in rat plasma for comparison of their pharmacokinetics.

Praziquantel is the drug of first choice for the control and treatment of all forms of schistosomiasis. Praziquantel is administered as a racemate, including R-enantiomer and S-enantiomer. Among them, R-enantiomer has main contribution to schistosomicidal activity. In this study, a sensitive and rapid liquid chromatography with tandem mass spectrometry was established and validated to determine the concentration of racemate praziquantel and R-enantiomer in rat plasma after oral administration. Chromatographic separation was performed on an Agilent Zorbax SB-C18 column. An entire run time for chromatographic separation was no more than 5min. The present method for analytes manifested that high sensitivity (the lower limit of quantification was 3.0ng/mL), satisfactory accuracy (relative error ≤±15%) and precision (relative standard deviation ≤15%) were achieved. There was no obvious matrix effect found. The average recoveries of racemate praziquantel and R-enantiomer were both above 85%. Then, the developed method had a successful application to comparative pharmacokinetic study of racemate praziquantel and R-enantiomer. Meanwhile, the differences in their pharmacokinetic parameters were compared and analyzed. The present quantification method and comparative pharmacokinetic study would provide a useful reference for the drug development of enantiopure schistosomicidal R-enantiomer as a replacement of racemate praziquantel for treatment of schistosomiasis.

Bioavailability and pharmacokinetics of a praziquantel bolus in kingfish Seriola lalandi.

Oral praziquantel (PZQ) preparations have recently been investigated for the treatment of monogeneans that infect the skin and gills of kingfish Seriola lalandi cultured in sea-cages. To evaluate an oral PZQ dosing strategy, the pharmacokinetics of a dissolved and in feed oral PZQ preparation (40 mg kg(-1) body weight) were compared with an intravenous bolus in kingfish plasma and skin using HPLC. Compared with intravenous administration, PZQ bioavailability (area under curve, AUC0-24h) was slightly improved when the drug was administered with food in both kingfish plasma (56.8% in feed vs. 50.8% in solution) and skin (55.5% in feed vs. 50.3% in solution). After oral dosing, maximum drug concentrations in skin were approximately one-third of those achieved in plasma and higher when the drug was administered in solution (5.26 microg ml(-1)) than in feed (3.96 microg ml(-1)); additionally, the time to achieve maximum PZQ concentration was similar in plasma and skin, although markedly reduced when the drug was administered in solution (1 h) than in feed (6 h). However, clearance of the drug was delayed in skin; administered as an oral formulation, PZQ concentrations in the systemic circulation fell below the limit of quantification after 24 h, but remained quantifiable (0.3 microg g(-1)) in skin at this time. These initial studies indicate that a daily treatment interval will lead to the exposure of parasites to highly variable anthelmintic concentrations, which may be sub-optimal for the treatment of monogeneans in this finfish species.

Preclinical pharmacokinetic evaluation of praziquantel loaded in poly (methyl methacrylate) nanoparticle using a HPLC-MS/MS.

Praziquantel (PZQ) is the drug recommended by the World Health Organization for treatment of schistosomiasis. However, the treatment of children with PZQ tablets is complicated due to difficulties to adapt the dose and the extremely bitter taste of PZQ. For this reason, poly (methyl methacrylate) nanoparticles loaded with Praziquantel (PZQ-NP) were developed for preparation of a new formulation to be used in the suspension form. For this reason, the main aim of the present study was to evaluate the pharmacokinetic (PK) profile of PZQ-NP, through HPLC-MS/MS assays. Analyses were performed with an Omnisphere C18 column (5.0 µm×4.6 mm×150.0 mm), using a mixture of an aqueous solution containing 0.1 wt% of formic acid and methanol (15:85-v/v) as the mobile phase at a flow rate of 0.800mL/min. Detection was performed with a hybrid linear ion-trap triple quadrupole mass spectrometer with multiple reactions monitoring in positive ion mode via electrospray ionization. The monitored transitions were m/z 313.18>203.10 for PZQ and m/z 285.31>193.00 for the Internal Standard. The method was validated with the quantification limit of 1.00 ng/mL, requiring samples of 25 µL for analyses. Analytic responses were calibrated with known concentration data, leading to correlation coefficients (r) higher than 0.99. Validation performed with rat plasma showed that PZQ was stable for at least 10 months when stored below -70 °C (long-term stability), for at least 17 h when stored at room temperature (RT, 22 °C) (short-term stability), for at least 47 h when stored at room temperature in auto-sampler vials (post-preparative stability) and for at least 8 successive freeze/thaw cycles at -70 °C. For PK assays, Wistar rats, weighing between 200 and 300 g were used. Blood samples were collected from 0 to 24 h after oral administration of single doses of 60 mg/kg of PZQ-NP or raw PZQ (for the control group). PZQ was extracted from plasma by liquid-liquid extraction with terc-butyl methyl ether. The values obtained for maximum concentration (C(max)) and area under curve (AUC) for the PZQ-NP group were about 3 times smaller than the respective values obtained for the control group. However, the time for achieving maximum concentration (T(max)), the elimination constant (Ke) and the half-life time of elimination (T(½ß)) were not statistically different. These results suggest that PZQ absorption is probably the rate-limiting step for obtainment of better PK parameters for PZQ-NP. Thus, further studies are needed to understand both the PZQ-NP absorption mechanisms and the drug diffusion process through the polymer matrix in vivo, in order to improve the PZQ-NP release profile.

Enantioselective simultaneous analysis of selected pharmaceuticals in environmental samples by ultrahigh performance supercritical fluid based chromatography tandem mass spectrometry.

In order to assess the true impact of each single enantiomer of pharmacologically active compounds (PACs) in the environment, highly efficient, fast and sensitive analytical methods are needed. For the first time this paper focuses on the use of ultrahigh performance supercritical fluid based chromatography coupled to a triple quadrupole mass spectrometer to develop multi-residue enantioselective methods for chiral PACs in environmental matrices. This technique exploits the advantages of supercritical fluid chromatography, ultrahigh performance liquid chromatography and mass spectrometry. Two coated modified 2.5 µm-polysaccharide-based chiral stationary phases were investigated: an amylose tris-3,5-dimethylphenylcarbamate column and a cellulose tris-3-chloro-4-methylphenylcarbamate column. The effect of different chromatographic variables on chiral recognition is highlighted. This novel approach resulted in the baseline resolution of 13 enantiomers PACs (aminorex, carprofen, chloramphenicol, 3-N-dechloroethylifosfamide, flurbiprofen, 2-hydroxyibuprofen, ifosfamide, imazalil, naproxen, ofloxacin, omeprazole, praziquantel and tetramisole) and partial resolution of 2 enantiomers PACs (ibuprofen and indoprofen) under fast-gradient conditions (<10 min analysis time). The overall performance of the methods was satisfactory. The applicability of the methods was tested on influent and effluent wastewater samples. To the best of our knowledge, this is the first feasibility study on the simultaneous separation of chemically diverse chiral PACs in environmental matrices using ultrahigh performance supercritical fluid based chromatography coupled with tandem mass spectrometry.

Structural characterization and enantioseparation of the chiral compound praziquantel.

In this study, we aimed to characterize the chiral compound type of a leading antischistosomal drug, praziquantel. The optically pure praziquantel enantiomers were recovered from the racemic mixture by enantiomeric separation, which was performed on preparative scale chromatography by using a novel beta-cyclodextrin type chiral column. The thermodynamic properties of praziquantel were determined from differential scanning calorimetry and the physical properties were studied by examining Fourier transform infrared spectroscopy and X-ray powder diffraction. Based on the differential scanning calorimetry data, a melting point binary phase diagram was constructed. A ternary solubility phase diagram of praziquantel in methanol was also determined at the temperature of 0 degrees C. All the experimental results support the conclusion that praziquantel is a racemic compound. The characterization of physical properties of praziquantel and the phase diagram are crucial for understanding the rationality for the successful resolution of praziquantel and also provide the basis for designing the strategy of separation and recovery of pure enantiomer.

Direct determination of praziquantel in pharmaceutical formulations and human plasma by cathodic adsorptive stripping differential-pulse voltammetry.

The polarographic and cyclic voltammetric behaviour of praziquantel was studied in B.R. buffers of different pH values. Contradictory to that mentioned in a previously published work, praziquantel is an electro-active compound. Its polarogram exhibited a single 2-electron irreversible reduction wave in B.R. buffer of pH 5, the wave height decreased on the increase of pH till it disappeared in solution of pH >7. This wave was attributed to the reduction of the Cz.dbnd6;O double bond. The quantitative trace determination of bulk praziquantel was studied at a hanging mercury drop electrode by cathodic adsorptive stripping differential-pulse voltammetry. A fully validated sensitive procedure based on controlled adsorptive accumulation of the drug onto a HMDE was developed for its direct determination without derivatization. Accumulation of praziquantel was found to be optimized in 0.1 M Na(2)SO(4) solution as supporting electrolyte under the following conditions: accumulation potential, -1.2 V (vs. Ag/AgCl/KCl(s)); accumulation time, 30 s; scan rate, 10 mV/s and pulse height 100 mV. The proposed procedure was applied successfully for determination of praziquantel in its pharmaceutical formulations and human plasma. The mean recoveries of the drug were 98.85-99.42% and 99.12-100.47% with RSD of 0.49-0.95% and 0.45-0.52% in pharmaceutical formulations and human plasma, respectively. Limits of detection and quantitation of 1.14x10(-9) and 3.80x10(-9) M praziquantel, respectively, were achieved.

Vilsmeier formylation of praziquantel: synthesis and application for polarographic assay.

A simple and sensitive method for the polarographic determination of praziquantel (1) after derivatization using Vilsmeier formylation is described. The polarographically active compound obtained by this procedure has been separated, identified and prepared using N,N-dimethylformamide and phosphorus oxychloride.

Quantitative studies on the occurrence of praziquantel in milk and plasma of lactating women.

10 healthy lactating women were treated orally with the anthelmintic praziquantel (Biltricide), and the resulting timedependent concentrations of the unchanged substance in plasma and milk were determined simultaneously. 5 of the women ("1st trial") received the single dose of 50 mg/kg; the other 5 women ("2nd trial") were treated three times at 4 hour intervals with 20 mg/kg. During the 1st trial a maximal plasma-concentration of 1.30 mg/l (arithmetic mean) was found. Subsequently the mean plasma-concentration decreased continuously and after 24 h it was only 0.4% of the maximum. During the 2nd trial the highest mean value (1.92 mg/l) was found 10 h after the first administration; after 32 h (24 h after the last administration) the mean value was 0.6% of the maximum mean value. The mean areas under the concentration/time-curves were 5.25 h. mg/l and 13.8 h . mg/l, respectively. The plasma half-life was estimated to be 3 hours. In both trials the concentration/time-curves of the milk corresponded qualitatively to those of the plasma. However, in each person and at each time, the concentration in the milk were essentially lower than those in the plasma. On the average, the plasma-concentrations were four times higher than the milk-concentrations. The mean values of the milk-concentrations increased and decreased correspondingly with those of the plasma-concentrations. At the end of the investigation (24 and 32 h, respectively, from the beginning) they were lower than the limit of determination (4 microgram/l). The mean excretion with the milk of the 10 women was 0.0008% of the given dose. From the comparative concentration/time-course, it could be demonstrated that the milk does not represent a deep department but readily equilibrates with the plasma. Equilibration obviously takes place by passive diffusion and not by active secretion.

Quantitative determination of praziquantel in body fluids by gas liquid chromatography.

Praziquantel was determined in body fluids by gas liquid chromatography as follows: A known amount of an internal standard and 0.1 N sodium hydroxide solution was added to the sample to be analyzed. After extraction with methyl acetate/diisopropyl ether = 30/70, the organic extract was evaporated, the residue taken up in methylacetate and an aliquot injected for glc analysis. Separation was accomplished on a OV3 silicon oil phase, and for detection and quantitation, a thermoionic FID sensitized for nitrogen-containing compounds was used. The determination limit in serum is about 0.01 micrograms/ml. The relative standard deviation for serum concentrations of 0.1 micrograms/ml was found to be 4.5%.

A fluorometric method for the determination of praziquantel in blood-plasma and urine.

Some physicochemical data of praziquantel which may have analytical relevance are reported. For the quantitative determination praziquantel is extracted from plasma or urine by means of organic solvents and then hydrolyzed in an aqueous alkaline solution. The hydrolyzed product is reacted with dansyl-chloride (5-dimethylaminonaphthalene-sulfonylchloride). The dansylated compound is separated and quantified fluorometrically. The limit of determination is 3 micrograms/l in blood plasma and 30 micrograms/d in urine. For both fluids, the imprecision is approximately 7.5%. The method is suitable for the determination of praziquantel in patients or healthy volunteers treated with therapeutic doses.