ABSTRACT
The examination of drug accumulation within complex biological systems offers valuable insights into the molecular aspects of drug metabolism and toxicity. Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) is an innovative methodology that enables the spatial visualization and quantification of biomolecules as well as drug and its metabolites in complex biological system. Hence, this method provides valuable insights into the metabolic profile and any molecular changes that may occur as a result of drug treatment. The renal system is particularly vulnerable to adverse effects of drug-induced harm and toxicity. In this study, MALDI MSI was utilized to examine the spatial distribution of drug and renal metabolites within kidney tissues subsequent to a single oral dosage of the anticancer compound rotenone. The integration of ion mobility spectrometry with MALDI MSI enhanced the data acquisition and analysis, resulting to improved mass resolution. Subsequently, the MS/MS fragment ions of rotenone reference drug were detected and characterized using MALDI HDMS/MS imaging. Notably, drug accumulation was observed in the cortical region of the representative kidney tissue sections treated with rotenone. The histological examination of treated kidney tissues did not reveal any observable changes. Differential ion intensity of renal endogenous metabolites was observed between untreated and rotenone-treated tissues. In the context of treated kidney tissues, the ion intensity level of sphingomyelin (D18:1/16:0), a sphingolipid indicator of glomerular cell injury and renal damage, was found to be elevated significantly compared to untreated kidney tissues. Conversely, the ion intensities of choline, glycero-3-phosphocholine (GPC), inosine, and a lysophosphatidylcholine LysoPC(18:0) exhibited a significant decrease. The results of this study demonstrate the potential of MALDI MSI as a novel technique for investigating the in situ spatial distribution of drugs and renal endogenous molecules while preserving the anatomical integrity of the kidney tissue. This technique can be used to study drug-induced metabolism and toxicity in a dynamic manner.
ABSTRACT
Objectives: Bioequivalence studies provide evidence that generic drugs can produce the same blood levels as the innovator, suggesting similar efficacy and safety and indicating interchangeability without the need to titrate dosing. This study aimed to compare the rate and extent of absorption of two simvastatin 20 mg tablets of Pascual Laboratories, Inc. with two Zocor 20 mg tablets of Merck Sharp & Dohme (I.A.) Corp. in healthy Filipinos. The study also monitored the safety and tolerability of the medications, under the same conditions. Proof of bioequivalence is required by FDA Philippines to establish the interchangeability of generic products and their innovators. Methods: Twenty-four healthy participants were administered with a single oral dose of two 20 mg simvastatin tablets under fasting conditions, in a randomized, open-label, blind-endpoint analysis, two-way crossover study, with a washout period of one week. Pharmacokinetic blood sampling was done up to 24 h post-dose. Simvastatin was measured using Liquid Chromatography-Tandem Mass Spectrometry with a validated method. The geometric mean ratios for maximum plasma concentration (Cmax) and area under the plasma-concentration-time curve from time zero to the last observed concentration at time 24 h (AUC0-24) were used for bioequivalence. Results: All 24 participants, 12 males and 12 females, completed the study. Mean age was 24.21 years, mean weight was 58.81 kg, and mean BMI was 23.16 kg/m2. The ratios of Cmax and AUC0-24 were 102.17% (90% CI: 89.19-117.03), and 101.29% (90% CI: 86.87-118.10), respectively, and were both within the bioequivalence limits of 80% to 125%. No adverse event was reported and both formulations were well-tolerated. Conclusion: Simvastatin 20 mg tablet of Pascual Laboratories, Inc. and the innovator Zocor 20 mg tablet are bioequivalent. Single two-tablet doses of both products are safe and well tolerated.
