The using of a piglets as a model for evaluating the dipyrone hematological effects

Pharmacokinetic profiles of the two major active metabolites of metamizole, 4-methylaminoantipyrine (MAA) and 4-aminoantipyrine (AA), after intravenous injection in cats

This study aimed to determine the pharmacokinetic profile of two active metabolites of metamizole (dipyrone), N-methyl-4-aminoanthypyrine (MAA) and 4-aminoanthypyrine (AA), after intravenous administration in cats. Eight healthy mixed-breed cats were intravenously administered metamizole (25 mg/kg). Blood samples were collected at predetermined time points for up to 48 h after administration. Information on behavioral changes in the animals and adverse effects was collected. Plasma aliquots were processed and analyzed using the ultra-performance liquid chromatography tandem mass spectrometry technique. A validated UPLC-MS/MS method was used to characterize the pharmacokinetics of MAA and AA. Salivation was identified as an adverse clinical sign. The mean maximal plasma concentrations of MAA and AA were 29.31 ± 24.57 μg/mL and 1.69 ± 0.36 μg/mL, with half-lives of around 4.98 and 14 h, respectively. The area under the plasma concentration curve values were 28.54 ± 11.33 and 49.54 ± 11.38 h*μg/mL for MAA and AA, respectively. The plasma concentration of MAA was detectable for up to 24 h and was smaller than AA. AA was detectable for >48 h. Results suggest that metamizole is converted into active metabolites in cats. Further PK/PD and safety studies should be performed before defining the dose or administration intervals for clinical use.

Ustekinumab pharmacokinetics after subcutaneous administration in swine model

BACKGROUND

Due to multiple similarities in the structure and physiology of human and pig skin, the pig model is extremely useful for biological drug testing after subcutaneous administration. Knowledge of the differences between subcutaneous injection sites could have a significant impact on the absorption phase and pharmacokinetic profiles of biological drugs.

OBJECTIVES

This study aimed to analyze the impact of administration site on pharmacokinetics and selected biochemical and hematological parameters after a single subcutaneous administration of ustekinumab in pigs. Drug concentrations in blood plasma were analyzed by enzyme-linked immunosorbent assay. Pharmacokinetic analyses were performed based on raw data using Phoenix WinNonlin 8.1 software and ThothPro v 4.1.

METHODS

The study included 12 healthy, female, large white piglets. Each group received a single dose of ustekinumab given as a 1 mg/kg subcutaneous injection into the internal part of the inguinal fold or the external part of the inguinal fold.

RESULTS

The differences in absorption rate between the internal and external parts of the inguinal fold were not significant. However, the time of maximal concentration, clearance, area under the curve calculated between zero and mean residence time and mean residence time between groups were substantially different (p > 0.05). The relative bioavailability after administration of ustekinumab into the external part of the inguinal fold was 40.36% lower than after administration of ustekinumab into the internal part of the inguinal fold.

CONCLUSIONS

Healthy breeding pigs are a relevant model to study the pharmacokinetic profile of subcutaneously administered ustekinumab.

Pharmacokinetic properties of metamizole active metabolites in Northeastern Brazilian donkeys (Equus asinus)

Metamizole (MT), also known as dipyrone, is an analgesic and antipyretic drug labeled for use in humans and domestic animals in some countries. As with other drugs, the administration of MT in donkeys is based on studies carried out with horses. In the present report, we aimed to determine the pharmacokinetics of the two main metamizole active metabolites (N-methyl-4-aminoantipyrine [MAA] and 4-aminoantipyrine [AA]) following 10 (M₁₀ ) and 25 mg/kg (M₂₅ ) IV metamizole doses in Northeast Brazilian donkeys (n = 10). Blood was collected at predetermined times within over 48 h; MAA and AA plasma concentrations were determined by a validated LC-MS/MS method. The metabolites were quantifiable in the M₁₀ until 12 h and M₂₅ until 24 h after drug administration. As expected, AUC_0→t , AUC_0→∞, and C_max demonstrated significant differences increases in metamizole metabolites profiles when groups were compared. No adverse effects were observed. This study indicates the need for an extremely sensitive analytical method to adequately characterize the pharmacokinetics of active metabolites of MT, MAA, and AA. In conclusion, the method developed in this research was able to measure the active metabolites of metamizole and with that it was possible to establish their pharmacokinetic profile. Furthermore, after projection of the minimum MAA concentrations, it is possible to infer that the dose of 10 mg/kg will be used on donkeys at 6 h intervals, while the M25 group at 12 h intervals. However, clinical studies are needed to assess this hypothesis.