No abstract

Nicotine (Nic) distribution in human fluids and tissues has a deleterious effect on human health. In addition to its poisoning profile, Nic may contribute to the particular impact of smoking on human reproduction. Although present in seminal fluid, still nobody knows whether nicotine is available in sperm or not. Herein, we developed and validated a new bioanalytical method, for simultaneous determination of Nic, cotinine (Cot), and nicotine N'-oxide (Nox) in human plasma, semen, and sperm by LC-ESI-orbitrap-MS. Blood and semen samples were collected from 12 healthy smoking volunteers in this study. Sperm bodies were then separated quantitatively from 1 mL of semen samples by centrifugation. The developed method was fully validated for plasma following European and American guidelines for bioanalytical method validation, and partial validation was applied to semen analysis. Plasma, semen, and sperm samples were treated by trichloroacetic acid solution for protein direct precipitation in single extraction step. The established calibration range for Nic and Nox in plasma and semen was linear between 5 and 250 ng/mL, and for Cot between 10 and 500 ng/mL. Nic and Cot were detected in human sperm at concentrations as high as in plasma. In addition, Nox was present in semen and sperm but not in plasma. Graphical abstract Nicotine correlation between plasma and semen a; Nicotine correlation between semen and sperm c; Cotinine correlation between plasma and semen b; Cotinine correlation between semen and sperm d.

No abstract

Enalapril is an angiotensin-converting enzyme inhibitor used for treatment of hypertension and chronic heart disease. Enalaprilat is its active metabolite responsible for the activity. This study aimed to develop and validate a method for enalapril and enalaprilat analysis and to determine the bioequivalence of two tablet formulae of enalapril. LC-MS/MS bioanalytical method was developed and validated and then applied to evaluate the bioavailability of two enalapril formulae. Antihyperglycemic sitagliptin was used as internal standard (IS). The method was accurate for the within- and between-days analysis, and precise CV% was <5%, being linear over the calibration range 1.0–200.0 ng/ml. Stability was >85% and the LOD was 0.907 and 0.910 ng/ml for enalapril and enalaprilat, respectively, and LLOQ was 1 ng/ml. The pharmacokinetic parameters Cmax, tmax, AUC0–72, and AUC0–∞ values of enalapril and enalaprilat of the two formulae were calculated and nonsignificant differences were found. A linearity, specific, accurate, and precise method was developed and applied for the analysis of enalapril and enalaprilat in human plasma after oral administration of two formulae of enalapril 20 mg tablets in healthy volunteers. Depending on the statistical analysis it was concluded that the two enalapril formulae were bioequivalent.