| Praziquantel (PZQ) is a member of acylated isoquinoline-pyrazine with broad-spectrum antischistosome, antitrematode and anticestode activities. Praziquantel is the choice durg for the treatment of schistosomiasis of domestic animals, and its traditional dosage forms are tablets and powder. Domestic animals, especially cattle, have poor absorption, low bioavailability and obvious first-pass effect when praziquantel is administered orally. So it is very necessary to develop a praziquantel injection. In order to ensure that the preparation is stable, safe, effective and with controllable quality, quality research, stability test, pharmacokinetics test, clinical therapeutic trials and target ainimal safety test of30%praziquantel injection were carried out.1Quality reasearch of praziquantel injectionQuality reasearch of30%praziquantel injection was carried out to provide the basis for quality standard. The results of appearance, granularity and dispersity inspection test showed that praziquantel injection was white or almost white oil suspension, which will be layered after long time, and became suspension after being shaken. Praziquantel injection was identificated by the UV absorption spectrum and HPLC method. The results of sterility test of praziquantel injection was qualified by membrane-filter procedure. HPLC method was used to determine the content of praziquantel. HPLC analysis was carried out using a Diamonsil C18column (150mm×4.6mm,5μm) with ultraviolet detector at a wavelength of210nm. The column temperature was25℃. The mobile phase, a mixture of acetonitrile and water (60:40), was delivered at a flow rate of1.0mL/min. The injection volume was20μL. Excellent line relationship was obtained in the range of6.037to90.55μg/mL (r=0.9993). The average recovery rate was99.24%(RSD=0.77%). The results suggested that the established method was simple, sensitive and accurate with good repeatability, which could be used for quality control of praziquantel injection. The research confirmed that the formulation of30%praziquantel injection was reasonable, the preparation process was feasible and the quality was controllable.2Stability test of praziquantel injectionStability test of30%praziquantel injection was carried out to provide the basis for storage conditions and validity period. Stability of praziquantel injection was studied by stress test, accelerated stability test and long-term stability test. Praziquantel injection was stable to temperature (60℃) and unstable to light (45001x±500lx), during10days in stress test. No obvious changes of the appearance and content of praziquantel injection were observed during6months in accelerated test or during24months in long-term stability test. It could be forecasted that period of validity of praziquantel injection was two years stored under room temperature (25℃) and away from light.3Pharmacokinetics of praziquantel injection in buffalosThe pharmacokinetics of praziquantel were investigated and compared in6healthy buffalos in a crossover design following single intramuscular administration (10mg/kg) of30%praziquantel injection and oral administration (20mg/kg) of praziquantel tablet. Praziquantel concentration in plasma was determined by a high performance liquid chromatography method. The concentration-time data were analyzed with3P97computer program. The concentration-time data of praziquantel tablet were fitted to a one-compartment open model, and the main pharmacokinetic parameters were as follows:T1/2ka0.29±0.16h, T1/2ke0.70±0.42h, Tmax0.60±0.29h, Cmax0.47±0.37μg/mL, AUC0.80±0.70(μg/mL)·h. The concentration-time data of praziquantel injection were fitted to a one-compartment open model, and the main pharmacokinetic parameters were as follows:T1/2ka0.32±0.35h, T1/2ke1.00±0.73h, Tmax0.65±0.49h, Cmax0.82±1.17μg/mL, AUC1.61±0.89(μg/mL)·h. Praziquantel was well-adsorbed into blood after intramuscular administration, but poorly absorbed after oral administration in buffalos. Compared with praziquantel tablet, the relative bioavailability of praziquantel injection was402.5%. The results showed that the30%praziquantel injection demonstrated rapid absorption, high bioavailability and extensive distribution.4Clinical therapeutic trials of schistosomiasis with praziquantel injection in buffalosTo observe the clinical curative effect of30%praziquantel injection to schistosomiasis in buffalos, the sick buffalos naturally infected with Schistosoma japonicum were selected by miracidium hatching method. In experimental clinical trials, sick buffalos were randomly divided into five groups, praziquantel injection high-dose group (20mg/kg, i.m.), praziquantel injection middle-dose group (10mg/kg, i.m.), praziquantel injection low-dose group (5mg/kg, i.m.), praziquantel tablet group (30mg/kg, p.o.) and blank group. After the treatment of30days, negative conversion rate of miracidium were100%,100%,77.8%and85.7%, respectively, in praziquantel injection groups with the high, moderate and low dose and oral medication group. In expanded clinical trials, the sick buffalos were randomly divided into two groups, praziquantel injection group (10mg/kg, i.m.) and praziquantel tablet group (30mg/kg, p.o.).The results showed that negative conversion rate of miracidium were all100%in the former52patients and the latter6patients. The research confirmed that praziquantel injection was significantly effective in the treatment of cattle schistosomiasis and convenient for administration. And thus30%praziquantel injection can replace the traditional oral praziquantel tablet for the treatment of cattle schistosomiasis. The recommended dose of30%praziquantel injection is10mg/kg.5Target ainimal safety test of praziquantel injection in BuffalosThe target ainimal safety of30%praziquantel injection in buffalos was evaluated to provide the basis for clinical application. Twenty-four healthy buffalos were randomly divided into three experiment groups and one control group.30%praziquantel injection was administered by neck intramuscular injection at a dosage of10,30,50mg/kg once daily for three days, respectively. Blood samples were collected from jugular vein before administration and after the last administration of12hours and72hours. Blood routine and serum biochemistry indices of buffalos were tested and analyzed. And clinical features of experimental animals were observed daily. The results showed that there was no obvious clinic symptom in buffalos during the experiment. And the blood routine and biochemical indices in each experiment group were within the normal range. The blood routine indices and serum biochemistry indices in1-fold and3-fold dose group had no statistical differences compared with those in control group and before administration (P>0.05). Compared with control group, glutamyl transpeptidase (GGT) and Urea nitrogen (UN) in5-fold dose group were significantly altered after the last administration for12hours (P<0.05), but no statistical differences was found after the last administration for72hours (P>0.05). The results suggested that the30%praziquantel injection was safe and had no adverse reactions to clinical sign, hematological indexes and blood biochemical indexes of buffalos following the intramuscular administration of the recommended dose of10mg/kg. |
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