Quality Evaluation And Pharmacokinetics Study In Pigs Of Meloxicam Oil Suspension

As a new type of non-steroids anti-inflammatory drugs（NSAIDs）,meloxicam（MEL）has remarkable analgesic,antipyretic,and anti-inflammatory effects.It is a preferably cyclooxygenase-2（COX-2）inhibitor with a lower incidence of gastrointestinal side effects compared with other NSAIDs,deciding the advantage of it in safety,efficiency,and selection.The common MEL injection has been widely used to slow down acute and chronic musculoskeletal pain and inflammation in horses,cattle,pigs,etc.However,it has a huge stimulation and a short half-life,and in one course of treatment often needs repeated administration,which restricts its use.Based on this,we tried to prepare MEL oil suspension to make up the storage of common MEL injection.Firstly,the main indicators of MEL oil suspension was evaluated,such as needle penetration,sedimentation volume ratio,and content determination.Secondly,an analysis method of ultra performance liquid chromatography tandem mass spectrometry（UPLC-MS/MS）was established for the determination of MEL in the plasma of pigs.By this method,the pharmacokinetics of MEL oil suspension with different dosages were compared to evaluate the feasibility of oil suspension as a new drug carrier of MEL.1 Quality evaluation of MEL oil suspensionThe quality of self-developed MEL oil suspension was evaluated in terms of needle penetration,sedimentation volume ratio,and content determination.The results showed that MEL oil suspension could be successfully extracted by using the type of 6,7,8,and 9 needles,and the needle permeability met the requirements.The settling volume ratio of MEL oil suspension after standing 24 h was 0.948,while the settling curve was smooth and stable,showing that the stability of MEL oil suspensions was good.It also had good redispersibility.The determination method of MEL oil suspension was established and the content of it was detected.The chromatographic conditions were determined:methanol and 0.1 mol·L-1 ammonium acetate solution were used as mobile phase according to the volume ratio of 1:1.The detection wavelength was at 362 nm and the flow rate was 1 mL·min-1.The extraction method of MEL oil suspension was optimized.Based on this,the oil suspension was detected.The results showed that the established method had good specificity,accuracy,and repeatability,and the drug content was 100.58%of the labeled amount,which met the requirements.2 Establishment of an UPLC-MS/MS method for determination of MEL in pigs’plasmaIn this experiment,the sample pretreatment method was protein precipitation method.MEL in pigs’ plasma was extracted by acetonitrile.After concentration by nitrogen and redissolution by initial mobile phase（30%acetonitrile mixed with water）,the samples were eluted by an Acquity UPLC BEH C18 column.The multiple reaction monitoring mode（MRM）was selected under the electrospray ionization mode（ESI+）for detection and analysis on a three heavy four stage tandem mass spectrometer.The matrix effect of this method in pigs’ plasma was slight（85%≤ME≤115%）.The linearity of MEL was good（R2>0.99）.The detection limit（LOD）was 0.5 ng·mL-1 and the quantitative limit（LOQ）was 2 ng·mL-1.The recovery and the precision were met the requirements.It could be concluded that the method had good specificity,sensitivity,accuracy,and repeatability,and could be used for the quantitative detection of MEL in pigs’ plasma.3 Pharmacokinetics of MEL oil suspension in pigsSix healthy pigs（14±1kg）were randomly divided into two groups.The first group was injected by intramuscular administrated with 0.4 mg·kg-1b.w.of MEL injection and the second group was injected by intramuscular administrated with 0.4 mg·kg-1 b.w.of MEL oil suspension.About 4 mL of jugular blood was collected before administration（0 h）and after administration.After a washout period of 14 days,the cross-design test was carried out,and the two groups were injected with the opposite group’s drug.The other operations were the same as the first time.The plasma samples were pretreated according to the established method,and the plasma concentration was measured by the established UPLC-MS/MS method.The pharmacokinetic parameters were analyzed by Winnonlin software,and the relative bioavailability of MEL oil suspension was compared.The pharmacokinetic parameters of MEL injection were as follows:the mean half-life（t1/2λ）was（1.55±0.37）h,the peak time（Tmax）was（0.59±0.18）h,the peak concentration（Cmax）was（1.12±0.22）μg·mL-1,the area under the mean drug time curve（AUC0-∝）was（3.43±1.00）h·μg·mL-1,and the mean retention time（MRT）was（2.66±0.55）h.The pharmacokinetic parameters of MEL oil suspension were as follows:t1/2λ was（3.74±2.66）h,Tmax was（2.33±0.82）h,Cmax was（0.82±0.12）μg·mL-1,AUC0-∝ was（5.35±2.57）h.μg·mL-1,MRT was（6.16±4.04）h,and the relative bioavailability（Frel）was 155.98%.To sum up,compared with MEL injection,the t1/2λ and MRT of MEL oil suspension in pigs were significantly longer than that of MEL injection,indicating that the self-developed MEL oil suspension had a certain sustained-release effect.The other six healthy pigs（14±1 kg）were randomly divided into two groups.The first group was injected by intramuscular administrated with 0.8 mg·kg-1 b.w.of MEL oil suspension,and the second group was injected by intramuscular administrated with 2 mg·kg-1 b.w.of MEL oil suspension.About 4 mL of jugular blood was collected before administration（0 h）and after administration.After a washout period of 14 days,the cross-design test was carried out,and the two groups were injected with the opposite group’s drug.The other operations were the same as the first time.The sample pre-processing method and the data processing method were the same as before.The pharmacokinetic parameters of the 0.8 mg·kg-1 b.w.group were as follows:t1/2λ was（2.63±0.67）h,Tmax was（3.25±1.04）h,Cmax was（1.92±0.34）μg ·mL-1,AUC0-∝ was（14.70±3.61）h μg·mL-1,MRT was（5.90±1.12）h.The pharmacokinetic parameters of the 2 mg·kg-1 b.w.group were as follows:t1/2λ was（6.88±1.39）h,Tmax was（4.00±1.26）h,Cmax was（3.03±1.25）μg·mL-1,AUC0-∝ was（40.55±6.76）h μg·mL-1,MRT was（10.73±1.30）h.In conclusion,t1/2λ and MRT of MEL oil suspension were significantly longer at the dosage of 2 mg·kg-1 b.w.than that at the dosage of 0.8 mg·kg-1 b.w.,and the pharmacokinetic parameters were significantly different at different dosages.