Effects of Single and Repeated Doses on Disposition and Kinetics of Doxycycline Hyclate in Goats

Simple Summary

Doxycycline is used to treat bacterial infections such as pneumonia, skin and soft tissue infections, urinary tract infections, salmonellosis, and colibacillosis in goats. In goats, the single intravenous and intramuscular pharmacokinetics of doxycycline are known. However, there is no information regarding oral pharmacokinetics. This study aims to determine the single and repeated pharmacokinetics, bioavailability, and accumulation of doxycycline hyclate. Although doxycycline hyclate exhibited low intramuscular and oral bioavailability, its oral administration with favorable properties such as weak accumulation, wide distribution volume and long elimination half-life can be useful in the treatment of infections caused by susceptible pathogens in goats.

Abstract

The aims of this study in goats were to determine the pharmacokinetics of doxycycline hyclate following single intravenous (IV), intramuscular (IM) and oral administrations of 20 mg/kg and to evaluate the pharmacokinetics and accumulation of doxycycline hyclate after repeated oral administrations at a 20 mg/kg dose every 24 h for 5 days. Six healthy male goats were used for the study. The study was performed in four periods according to a longitudinal study with a 15-day washout period. Plasma concentrations of doxycycline were determined using HPLC-UV and analyzed by a non-compartmental method. IM injection of doxycycline caused swelling and pain due to irritation in the injection site. After IM and oral administrations, terminal elimination half-life (t_1/2λz) and mean residence time (MRT) were prolonged and areas under the curve (AUCs) were low. The mean bioavailability of IM and oral administration was 51.51% and 31.39%, respectively. Following repeated oral administration, the accumulation ratio of doxycycline was 1.76. Pharmacokinetic properties including weak accumulation, wide distribution volume and long elimination half-life can make doxycycline hyclate valuable for repeated use via an oral route in the treatment of some infectious diseases in goats. However, the determination of pharmacodynamic effects on susceptible pathogens isolated from goats is also necessary to confirm the drug dosage regimen.

Effect of ketoprofen co-administration on pharmacokinetics of cefquinome following repeated administration in goats

The pharmacokinetics of cefquinome (2 mg/kg every 24 hr for 5 days) was determined following intramuscular administration alone and co-administration with ketoprofen (3 mg/kg every 24 hr for 5 days) in goats. Six goats were used for the study. In the study, the crossover pharmacokinetics design with 20-day washout period was performed in two periods. Plasma concentrations of cefquinome were assayed using high-performance liquid chromatography by ultraviolet detection. The mean terminal elimination half-life (t_1/2ʎz ), area under the concentration-time curve (AUC_0-24 ), peak concentration (C_max ), apparent volume of distribution (V_darea /F), and total body clearance (CL/F) of cefquinome after the administration alone were 4.85 hr, 11.06 hr*µg/ml, 2.37 µg/mL, 1.23 L/kg, and 0.17 L/h/kg after the first dose, and 5.88 hr, 17.01 hr*µg/mL, 3.04 µg/mL, 0.95 L/kg, and 0.11 L/h/kg after the last dose. Ketoprofen significantly prolonged t_1/2ʎz of cefquinome, increased AUC_0-24 and C_max , and decreased V_darea /F and CL/F. Cefquinome exhibited low accumulation after the administration alone and in combination with ketoprofen. These results indicated that ketoprofen prolonged the elimination of cefquinome in goats. The 24-hr dosing intervals at 2 mg/kg dose of cefquinome, which co-administered with ketoprofen, may maintain T> minimum inhibitory concentration (MIC) values above 40% in the treatment of infections caused by susceptible pathogens with the MIC value of ≤0.75 μg/ml in goats with an inflammatory condition.

[Vaccination against SARS-CoV-2 and its relationship with illness and death from COVID-19 in ArgentinaVacinação contra SARS-CoV-2 e sua relação com doença e morte por COVID-19 na Argentina]

Objective

To determine the effectiveness of vaccination against SARS-CoV-2 in preventing illness and death from COVID-19 in Córdoba, Argentina, during the period from January through June 2021.

Methods

A retrospective cohort study was conducted among 1,139,458 residents of the province of Córdoba. Multiple logistic regression models were developed to describe the relationship between vaccination and the presence of SARS-CoV-2 or death from COVID-19, while taking account of comorbidities and chronic disease risk factors and adjusting for sex and age.

Results

Among the general population, having received one or two doses of vaccine reduced the risk of illness by 98.8% and 99.3%, respectively, and the risk of dying by 83% and 96.5%, respectively. Among those who developed COVID-19, the probability of dying was reduced by 57% and 80%, respectively. Regarding probability of death, risk increased with age, with being male, and with obesity, arterial hypertension, and diabetes mellitus.

Conclusion

Vaccination is effective and protects against the risk of getting COVID-19, developing severe disease, or dying. Having obesity, arterial hypertension, or diabetes mellitus, in descending order, increases the risk of death.

Immuno-toxicological evaluation of her1 cancer vaccine in non-human primates: a 6-month subcutaneous study

Purpose: A vaccine composition based on the extracellular domain of the human epidermal growth factor receptor 1 (HER1-ECD) and the combination of VSSP (very small size proteoliposomes) and Montanide ISA 51 adjuvants when used by intramuscular route, demonstrated promising results in preclinical studies. However, in order to avoid potential adverse events due to the use of Montanide, it is proposed to modify the vaccine formulation by using VSSP (very small size proteoliposomes) adjuvant alone, and to evaluate the quality of subcutaneously induced immune response. This study aimed to assess the immunotoxicological effects of HER1 vaccine in Cercopithecus aethiops.Materials and methods: Fifteen monkeys were randomized into four groups: Negative Control (Tris/NaCl, s.c.), Positive Control (200 µg HER1-ECD/VSSP/Montanide ISA-51 VG, i.m), Low Dose (200 µg HER1-ECD/VSSP/Tris NaCl, s.c.) and High Dose (800 µg HER1-ECD/VSSP/Tris NaCl, s.c). All monkeys received 7 doses and were daily inspected for clinical signs. Body weight, rectal temperature, cardiac and respiratory rates were measured during the study, and electrocardiographical and ophthalmological studies were performed. Humoral and cellular immune response and clinical pathology parameters were analyzed.Results: Animal's survival in the study was 100% (n = 15). Administration site reactions were observed in the Positive Control animals (n = 4). HER1 vaccine administered subcutaneously (High Dose Group) achieved good IgG antibody titers although lower than the Positive Control group, but with higher ability to inhibit HER1 phosphorylation. Conclusions: This suggests that the alternative of eliminating the use of Montanide in the HER1 vaccine preparation and the using subcutaneous route is feasible.

The effects of repeated doses of xylazine-ketamine and medetomidineketamine anesthesia on DNA damage in the liver and kidney

PURPOSE

This study evaluated the DNA damage caused by repeated doses of xylazine-ketamine and medetomidine-ketamine anesthesia in the liver and kidneys.

METHODS

In this study, 60 rats were used. The rats were divided into group 1 (xylazine-ketamine), and group 2 (medetomidine-ketamine), and these anesthetic combinations were administered to the rats at repeated doses with 30-min intervals. The effects of these anesthetic agents on the tumor necrosis factor-alpha gene for DNA damage were investigated.

RESULTS

According to the gene expression results, it was observed that a single dose of xylazine-ketamine was 2.9-fold expressed, while first and second repeat doses did not show significant changes in expression levels. However, in the case of the third repetition, it was observed to be 3.8-fold overexpressed. In the case of medetomidine-ketamine administration, it was observed that a single-dose application resulted in a 1.04-fold expression, while the first and the third repeat doses showed a significant down expression. The samples from the second repeat dose administration group were found to have insignificant levels of expression.

CONCLUSIONS

This study can contribute to understanding the safe anesthetic combination in research and operations in which xylazine-ketamine and medetomidine-ketamine combinations are used.

Investigations of an organic-inorganic nanotheranostic hybrid for pancreatic cancer therapy using cancer-in-a-dish andin vivomodels

The incidence of highly aggressive pancreatic cancer is increasing across the globe and is projected to increase to 18.6% by 2050. The mortality rate for this form of cancer is very high and the 5 y relative survival rate is only about 9%-10%. The 3D pancreatic cancer microenvironment exerts a major influence on the poor survival rate. A key factor is the prevention of the penetration of the chemotherapeutic drugs in the three-dimensional (3D) microenvironment leading to the development of chemoresistance which is a major contributor to the survival rates. Hence,in vitrostudies using 3D cultures represent a better approach to understand the effect of therapeutic formulations on the cancer cells when compared to conventional 2D cultures. In the present study, we have explored three different conditions for the development of a 3D pancreatic tumour spheroid model from MiaPaCa-2 and PanC1 cells cultured for 10 days using Matrigel matrix. This optimized spheroid model was employed to evaluate a multi-functional nanotheranostic system fabricated using chitosan nanoparticles co-encapsulated with the chemotherapeutic agent gemcitabine and gold-capped iron oxide nanoparticles for multimodal imaging. The effect of the single and multiple-dose regimens of the theranostic system on the viability of 3D spheroids formed from the two pancreatic cancer cell lines was studied. It was observed that the 3D tumour spheroids cultured for 10 days exhibited resistance towards free gemcitabine drug, unlike the 2D culture. The administration of the multifunctional nanotheranostic system on alternate days effectively reduced the cancer cell viability after five doses to about 20% when compared with other groups. The repeated doses of the nanotheranostic system were found to be more effective than the single dose. Cell line-based differences in internalization of the carrier was also reflected in their response to the nanocarrier with PanC1 showing better sensitivity to the treatment.In vivostudies revealed that the combination of gemcitabine and magnetic field induced hypothermia produced superior regression in cancer when compared with the chemotherapeutic agent alone by a combination of activating the pro-apoptotic pathway and heat-induced necrosis. Our results reveal that this multi-functional system holds promise to overcome the current challenges to treat pancreatic cancers.

Immunogenicity and reactogenicity of repeated intradermal mRNA COVID-19 vaccines administered as a second booster dose in a Thai geriatric population

Background

Geriatric populations are at an increased risk of severe presentations, hospitalization, and loss of life from COVID-19. Few studies have explored vaccination regimens in adults >65 years old. Repeated booster vaccination is required for high-risk populations as COVID-19 vaccine efficacy is short-lived. We compared the immunogenicity and reactogenicity of second intradermal (ID) COVID-19 booster vaccination with second intramuscular (IM) vaccination in older adults.

Methods

This single-center, open-labeled, prospective, cohort study conducted at Siriraj Hospital enrolled older adults ≥65 years old who previously received a first booster (third dose) mRNA vaccine (mRNA-1273 or BNT162b2) via ID or IM administration. Participants were allocated to receive a second booster of the same vaccine type and route as their first booster 16-17 weeks thereafter. Anti-SARS-CoV-2 receptor binding domain IgG and neutralizing antibody titers against Wuhan and Omicron subvariants (BA.1, BA.2, and BA.4/5) were measured 2 weeks after vaccination.

Results

Of 91 enrolled participants, 72.5% were women, with a median age of 75 years. Forty-nine participants (53.8%) received a second ID booster, and 42 (46.2%) received a second IM booster. Two weeks after the second booster, all groups generated anamnestic IgG antibody responses that were 5.41- to 10.00-fold higher than at baseline. Overall, higher antibody GMTs against Wuhan and Omicron subvariants were observed in IM compared with ID regimens. ID mRNA-1273 induced similar GMTs to IM BNT162b2 2 weeks after the second booster against Wuhan (486.77 [321.48, 737.05] vs. 472.63 [291.24, 767.01], respectively; p = 0.072). Higher GMTs against Omicron BA.1 (GMR [95% CI], 1.71 [1.39, 2.11]; p = 0.023), BA.2 (1.34 [1.11, 1.62]; p = 0.845), and BA.4/5 (1.10 [0.92, 1.33]; p = 0.531) were seen in all groups at 2 weeks after the second booster compared with 2-4 weeks after the first booster. Both local and systemic AEs were less frequent after the second than after the first booster, regardless of administrative route and vaccine type. Local AEs were significantly more frequent in ID mRNA-1273 arms than their respective BNT162b2 arms 2 weeks after the second booster (ID-mRNA-1273 vs. ID-BNT162b2: p ≤ 0.001).

Conclusion

Repeated fractional ID vaccination may be an alternative booster vaccination strategy for geriatric populations.

Juvenile toxicity of atropine sulfate eye drops in young rats

OBJECTIVES

This study was to investigate the effects of atropine sulphate eye drops (ASED)on the development of partial systems in young rats and their toxic reactions following repeated eye-drop administration over a period of 40 days.

METHODS

SD rats of 20 days old were randomly assigned to control group, 0.01, 0.02, and 0.04% ASED groups, with 60 females and 25 males per group. ASED was given by eye drops from PND21 onwards and normal saline was given in the control group at 10 μL/eye once a day for 40 days, in both right and left eyes. Rats of ASED groups were instilled with eye drops at the 10 μL/day per eye, from postnatal day 21 (PND21) to PND60 for 40 consecutive days. The clinical observation, body weight, food intake, physical development, physiological development, reproductive development, ophthalmic examination, intraocular pressure, and axial length of the rats were examined during the study period.

RESULTS

ASED at concentrations of 0.01, 0.02, 0.04%, dose levels of 0.002, 0.004, 0.008 mg/day per rat, had no toxicological effects on the clinical observation, body weight, food intake, physical development, physiological development, reproductive development, ophthalmic examination, intraocular pressure, and axial length in rats.

CONCLUSION

The no-observed-adverse-effect-level (NOAEL) of ASED in young SD rats equivalent to human over 2 years old was 0.008 mg/day at a concentration of 0.4 mg/mL.