Persistência do efeito otoprotetor: qual a duração da otoproteção à amicacina?

Há comprovação de que o fenômeno de resistência ocorre quando a dose não lesiva da amicacina protege as células ciliadas contra a ototoxicidade da própria amicacina. OBJETIVO: O objetivo deste trabalho é verificar se o fenômeno de resistência é temporalmente persistente. MÉTODO: Estudo experimental com 14 cobaias albinas (Cavia porcellus) divididas em três grupos. Avaliação da função auditiva por emissões otoacústicas por produto de distorção (EOAPD): na pré-exposição à amicacina, no 15º dia de aplicação da dose não lesiva, no final da aplicação da dose lesiva e antes da decapitação. RESULTADOS: O Grupo A (controle) apresentou função auditiva e padrão histológico normais. No Grupo B (amicacina 20mg/kg/dia intramuscular por 30 dias e dose lesiva (400 mg/kg/dia) por 12 dias) e no Grupo C (mesmo esquema do grupo B, porém mantidos por 60 dias e sacrificados), as OEA-PD confirmaram função auditiva normal no período pré-exposição e manutenção do padrão após dose não lesiva, porém, houve perda importante da função auditiva após término do período de aplicação da dose lesiva. CONCLUSÃO: Não houve manutenção do fenômeno da autodefesa estendida por um período de 30 a 60 dias após a aplicação de doses lesivas de amicacina.

Hydroxocobalamin quantification in human plasma by high-performance liquid chromatography coupled with electrospray tandem mass spectrometry in a pharmacokinetic study

A rapid, sensitive and specific method for quantifying hydroxocobalamin in human plasma using paracetamol as the internal standard (IS) is described. The analyte and the IS were extracted from plasma by liquid-liquid extraction using an organic solvent (ethanol 100%; -20°C). The extracts were analyzed by high performance liquid chromatography coupled with electrospray tandem mass spectrometry (HPLC-MS-MS). Chromatography was performed on Prevail C8 3 μm, analytical column (2.1×100 mm i.d.). The method had a chromatographic run time of 3.4 min and a linear calibration curve over the range 5-400 ng.mL-1 (r>0.9983). The limit of quantification was 5 ng.mL-1. The method was also validated without the use of the internal standard. The precision in the intra-batch validation with IS was 9.6%, 8.9%, 1.0% and 2.8% whereas without IS was 9.2%, 8.2%, 1.8% and 1.5% for 5, 15, 80 and 320 ng/mL, respectively. The accuracy in intra-batch validation with IS was 108.9%, 99.9%, 98.9% and 99.0% whereas without IS was 101.1%, 99.3%, 97.5% and 92.5% for 5, 15, 80 and 320 ng/mL, respectively. The precision in the inter-batch validation with IS was 9.4%, 6.9%, 4.6% and 5.5% whereas without IS was 10.9%, 6.4%, 5.0% and 6.2% for 5, 15, 80 and 320 ng/mL, respectively. The accuracy in inter-batch validation with IS was 101.9%, 104.1%, 103.2% and 99.7% whereas without IS was 94.4%, 101.2%, 101.6% and 96.0% for 5, 15, 80 and 320 ng/mL, respectively. This HPLC-MS-MS procedure was used to assess the pharmacokinetics of Hydroxo cobalamin following intramuscular injection 5000 μg in healthy volunteers of both sexes (10 males and 10 females). The volunteers had the following clinical characteristics (according to gender and expressed as mean ± SD [range]): males: age: 32.40 ± 8.00 y [23.00-46.00], height: 1.73 ± 0.07 m [1.62-1.85], body weight: 72.48 ± 10.22 Kg [60.20- 88.00]; females: age: 28.60 ± 9.54 y [18.00-44.00], height: 1.60 ± 0.05 m [1.54-1.70], body weight: 58.64 ± 6.09 Kg [51.70- 66.70]. The following pharmacokinetic parameters were obtained from the hydroxocobalamin plasma concentration vs. time curves: AUClast, T1/2, Tmax, Vd, Cl, Cmax and Clast. The pharmacokinetic parameters were 120 (± 25) ng/mL for Cmax, 2044 (± 641) ng.h/mL for AUClast, 8 (± 3.2) ng.mL-1 for Clast, 38 (± 15.8) hr for T1/2 and 2.5 (range 1-6) hr for Tmax. Female volunteers presented significant (p=0.0136) lower AUC (1706 ± 704) ng.h/mL) and larger (p=0.0205) clearance (2.91 ± 1.41 L/hr), as compared to male 2383 ± 343 ng.h/mL and 1.76 ± 0.23 L/hr, respectively. These pharmacokinetic differences could explain the higher prevalence of vitamin B12 deficiency in female patients. The method described validated well without the use of the internal standard and this approach should be investigated in other HPLC-MS-MS methods.

Dynamics of follicular growth and progesterone concentrations in cyclic and anestrous suckling Nelore cows (Bos indicus) treated with progesterone, equine chorionic gonadotropin, or temporary calf removal

The objective of this study was to investigate the effects of eCG and temporary calf removal (TCR) associated with progesterone (P4) treatment on the dynamics of follicular growth, CL size, and P4 concentrations in cyclic (n ¼ 36) and anestrous (n ¼ 30) Nelore cows. Cyclic (C) and anestrous (A) cows were divided into three groups. The control group received 2 mg of estradiol benzoate via intramuscular (IM) injection and an intravaginal device containing 1.9 g of P4 on Day 0. On Day 8, the device was removed, and the animals received 12.5 mg of dinoprost tromethamine IM. After 24 hours, the animals received 1 mg of estradiol benzoate IM. In the eCG group, cows received the same treatment described for the control group but also received 400 UI of eCG at the time of device removal. In the TCR group, calves were separated from the cows for 56 hours after device removal. Ultrasound exams were performed every 24 hours after device removal until the time of ovulation and 12 days after ovulation to measure the size of the CL. On the same day as the CL measurement, blood was collected to determine the plasma P4 level. Statistical analyses were performed with a significance level of P ≤ 0.05. In cyclic cows, the presence of the CL at the beginning of protocol resulted in a smaller follicle diameter at the time of device removal (7.4 ± 0.3 mm in cows with CL vs. 8.9 ± 0.4 mm in cows without CL; P ¼ 0.03). All cows ovulated within 72 hours after device removal. Anestrous cows treated with eCG or TCR showed follicle diameter at fixed-timed artificial insemination (A-eCG 10.2 ± 0.3 and A-TCR 10.3 ± 0.5 mm) and follicular growth rate (A-eCG 1.5 ± 0.2 and A-TCR 1.3 ± 0.1 mm/day) similar to cyclic cows (C-eCG 11.0 ± 0.6 and C-TCR 12.0 ± 0.5 mm) and (C-eCG 1.4 ± 0.2 and C-TCR 1.6 ± 0.2 mm/day, respectively; P ≤ 0.05). Despite the similarities in CL size, the average P4 concentration was higher in the A-TCR (9.6 ± 1.4 ng/mL) than in the A-control (4.0 ± 1.0 ng/mL) and C-TCR (4.4 ± 1.0 ng/mL) groups (P < 0.05). From these results, we conclude that eCG treatment and TCR improved the fertility of anestrous cows by providing follicular growth rates and size of dominant follicles similar to cyclic cows. Additionally, TCR increases the plasma concentrations of P4 in anestrous cows

A phase I randomized, double-blind, controlled trial of 2009 influenza A (H1N1) inactivated monovalent vaccines with different adjuvant systems

Methods We conducted a phase I, multicenter, randomized, double-blind, placebo-controlled, multi-arm (10) parallel study involving healthy adults to evaluate the safety and immunogenicity of influenza A (H1N1) 2009 non-adjuvanted and adjuvanted candidate vaccines. Subjects received two intramuscular injections of one of the candidate vaccines administered 21 days apart. Antibody responses were measured by means of hemagglutination-inhibition assay before and 21 days after each vaccination. The three co-primary immunogenicity end points were the proportion of seroprotection >70%, seroconversion >40%, and the factor increase in the geometric mean titer >2.5. Results A total of 266 participants were enrolled into the study. No deaths or serious adverse events were reported. The most commonly solicited local and systemic adverse events were injection-site pain and headache, respectively. Only three subjects (1.1%) reported severe injection-site pain. Four 2009 influenza A (H1N1) inactivated monovalent candidate vaccines that met the three requirements to evaluate influenza protection, after a single dose, were identified: 15 μg of hemagglutinin antigen without adjuvant; 7.5 μg of hemagglutinin antigen with aluminum hydroxide, MPL and squalene; 3.75 μg of hemagglutinin antigen with aluminum hydroxide and MPL; and 3.75 μg of hemagglutinin antigen with aluminum hydroxide and squalene. Conclusions Adjuvant systems can be safely used in influenza vaccines, including the adjuvant monophosphoryl lipid A (MPL) derived from Bordetella pertussis with squalene and aluminum hydroxide, MPL with aluminum hydroxide, and squalene and aluminum hydroxide.