Search Results (164)

This study aimed to investigate the effect of gender on the pharmacokinetics of meloxicam in goats following intravenous (IV, 0.5 mg/kg) and oral (PO, 1.0 mg/kg) administration. A crossover design was used with 12 clinically healthy Saanen goats (six females and six males). Plasma samples were collected up to 96 h post-administration and analyzed with an HPLC for meloxicam concentrations. Pharmacokinetic parameters were calculated and statistically compared between genders and administration routes. The results show that male goats exhibited significantly longer terminal half-life (T_1/2λz), a greater mean residence time (MRT_0–∞), and higher systemic exposure (AUC_0–∞) than females, particularly after oral administration. Oral bioavailability was calculated as 77.43% in females and 104.73% in males. These differences may be linked to gender-based variations in hepatic metabolism, enterohepatic recirculation, and the hormone-mediated modulation of cytochrome P450 activity. The findings are consistent with previous research demonstrating that gender can influence drug disposition through hormonal and enzymatic mechanisms. This study underscores the importance of considering gender as a biological variable in pharmacokinetic assessments of veterinary drugs, especially those used in food-producing animals, to optimize dosing strategies and ensure both therapeutic efficacy and food safety. Full article

Pregnancy introduces significant physiological changes that alter the pharmacokinetics (PK) of antiretroviral therapy (ART), impacting its safety and efficacy in HIV-positive women. Optimizing ART during pregnancy is critical to maintaining maternal virological suppression and preventing mother-to-child transmission (MTCT) of HIV. This review evaluates the impact of pregnancy-induced PK changes on ART and proposes strategies for tailored regimens to improve outcomes. A comprehensive review of published literature was conducted, focusing on PK adaptations during pregnancy and their implications for different ART classes, including protease inhibitors (PIs), integrase strand transfer inhibitors (INSTIs), and nucleoside reverse transcriptase inhibitors (NRTIs). Key studies were analyzed to assess drug exposure, efficacy, and safety. Pregnancy significantly alters the PK of antiretrovirals, with increased hepatic metabolism, renal clearance, and changes in plasma protein binding leading to reduced drug exposure. For example, drugs like lopinavir and atazanavir require dose adjustments, while dolutegravir maintains efficacy despite reduced plasma levels. Integrase inhibitors demonstrate favorable virological suppression, although cobicistat-boosted regimens show subtherapeutic levels. Tailored approaches, such as therapeutic drug monitoring (TDM), optimize ART efficacy while minimizing toxicity. Pregnancy-specific PK changes necessitate evidence-based ART adjustments to ensure virological suppression and reduce MTCT risk. Incorporating TDM, leveraging pharmacogenomic insights, and prioritizing maternal and neonatal safety are critical for personalized ART management. Further research into long-acting formulations and global guideline harmonization is needed to address disparities in care and improve outcomes for HIV-positive pregnant women. Full article

Sulfotransferase (SULT) enzymes contribute significantly to drug metabolism in pediatric patients. The purpose of this study was to develop a PBPK model for acetaminophen (APAP) in pediatric populations that accounts for the ontogeny of SULT isozymes that play a critical role in APAP metabolism. PBPK modeling and simulation were performed using the Simcyp^® Simulator. The model incorporated the developmental ontogeny of three key hepatic SULT enzymes: SULT1A1, SULT1A3, and SULT2A1 using “best-fit” ontogeny equations for each isozyme as determined by nonlinear regression analysis of enzyme abundance versus age. PBPK model-simulated pharmacokinetic profiles for APAP captured observed clinical data for systemic exposure (Cmax, AUC) in neonates, infants, and children. SULTS accounted for ~60% APAP metabolism in neonates, with decreased contributions to infants and children. Model sensitivity analysis highlighted the potential for APAP metabolic DDIs, primarily through SULT1A1. The study demonstrates that the impact of SULT enzymes on drug metabolism is significant in neonates, which is an important clinical consideration for APAP. A PBPK model that incorporates SULT ontogeny has the potential to help inform dosing decisions in this special patient population. Full article

Background: Locally acting gastrointestinal (GI) drugs present challenges for generic drug development because traditional bioequivalence measures, which rely on systemic drug levels, do not reflect local efficacy. This review examines regulatory guidelines for establishing therapeutic equivalence for such drugs, using rifaximin—a minimally absorbed, gut-localized antibiotic—as a case study. Methods: We reviewed bioequivalence guidelines from the United States Food and Drug Administration (FDA) and European Medicines Agency (EMA), along with the literature on rifaximin’s biopharmaceutical and clinical properties, to identify strategies and challenges for establishing equivalence for locally acting GI drugs. Results: Rifaximin exemplifies the limitations of standard bioequivalence methods: as a Biopharmaceutics Classification System (BCS) class IV drug with minimal absorption and low solubility, in vitro dissolution may not predict local drug availability. Clinical endpoint trials (e.g., traveler’s diarrhea, hepatic encephalopathy, IBS-D) are resource-intensive and insensitive to formulation differences. Pharmacokinetic (PK) studies in healthy volunteers show low, variable plasma levels, which may inaccurately discriminate between formulations. The EMA requires evidence of non-saturable absorption to accept PK data, a difficult-to-establish but potentially irrelevant criterion. Differences between FDA and EMA approaches highlight a lack of harmonization, complicating global generic development. Conclusions: A tailored, multifaceted approach is needed to demonstrate bioequivalence for GI-localized drugs like rifaximin. This case underscores the need for more sensitive surrogate methods (e.g. advanced in vitro or pharmacodynamic models) and flexible regulatory criteria. Harmonization across international guidelines and innovative bioequivalence study designs are key to facilitating the approval of safe and effective generic alternatives in this drug class. Full article

CYP2C9 and CYP2C19 are major CYP450 enzymes that heavily influence the hepatic metabolism and bioactivation of many medications, including over-the-counter and narrow therapeutic index drugs. Compared to the wild-type alleles, genetic variants in either gene could potentially alter the pharmacokinetics of widely used medications, affect the desired therapeutic outcomes of a drug therapy, or increase the risk of undesired adverse events. The frequency of genetic polymorphisms associated with CYP450 enzymes can widely differ across and between racial and ethnic groups. This narrative review highlights the differences in CYP2C9 and CYP2C19 allele frequencies among European and Asian population subgroups, using published literature. Identifying the substantial differences across European and Asian populations, as well as within Asian subgroups, indicates the need to further scrutinize general population data. Clinical scientists and healthcare providers should advocate for more inclusive clinical pharmacogenomic data and racially and ethnically diverse pharmacogenomic databases. Clinical trials of limited racial and geographical diversity may not necessarily have strong external generalizability for all populations. Furthermore, clinical trials that designate an all-inclusive Asian population consisting of multiple ethnicities may not be adequate due to the perceived genetic differences among Asian subgroups. Gravitating towards a more comprehensive approach to utilizing pharmacogenomic data necessitates granular population-level genetic information which can be leveraged to improve how drug therapies are prescribed, achieve health equity, and advance the future of precision medicine. Full article

Background: Olanzapine (Ola) is a second-generation antipsychotic with clinical utility limited by poor brain bioavailability due to blood–brain barrier restriction, hepatic first-pass metabolism, and systemic side effects. This study aimed to develop and optimize a novel intranasal polymersome-based nanocarrier (Poly_Ola) to enhance brain targeting, therapeutic efficacy, and safety of Ola. Methods: Poly_Ola was prepared using poloxamer 401 and optimized through a Box–Behnken Design to minimize particle size and maximize entrapment (EE%) and loading efficiency (LE%). The formulation was characterized by size, morphology, drug release, and serum stability. In vivo studies in adult male Sprague-Dawley rats assessed pharmacokinetics (plasma and brain concentrations), pharmacodynamic efficacy in a ketamine-induced schizophrenia model, and systemic safety markers including metabolic, hepatic, and testicular oxidative stress indicators. Results: Optimized Poly_Ola exhibited a particle size of 78.3 ± 4.5 nm, high EE% (91.36 ± 3.55%), and sustained in vitro drug release. It remained stable in serum for 24 h. Intranasal administration significantly improved brain delivery of Ola, achieving a 2.7-fold increase in C_max and a 5.7-fold increase in AUC compared to oral dosing. The brain T_max was 15 min, with high drug-targeting efficiency (DTE% = 365.38%), confirming efficient nose-to-brain transport. Poly_Ola-treated rats showed superior antipsychotic performance, reduced extrapyramidal symptoms, and improved systemic safety evidenced by mitigated weight gain, glycemic control, normalized liver enzymes, and reduced oxidative stress. Conclusions: Poly_Ola offers a safe and effective intranasal delivery platform for Ola, enabling targeted brain delivery and improved management of schizophrenia with reduced peripheral toxicity. Full article

Background/Objectives: Sustained drug exposure is a key factor in the treatment of patients infected with human immunodeficiency virus (HIV) or hepatitis B virus (HBV) in order to achieve the intended virological response. Although influenced also by other parameters, adherence to the treatment scheme is the most important for adequate drug exposure. This can be assessed by therapeutic drug monitoring (TDM). Tenofovir (TFV) is a nucleotide analogue used in the treatment of both HIV and HBV. Although various analytical methods for the quantification of tenofovir prodrugs have been published, there is limited literature on methods for simultaneous TFV and its active metabolite, tenofovir diphosphate (TFVDP) direct determination. Methods: In this study, we describe a novel micro-liquid-chromatography-mass spectrometry (micro-LC-MS/MS) method for TDM of TFV and TFVDP in biological matrices (whole blood, plasma). The challenging separation of the high-polarity analytes was resolved on an amino stationary phase, eluted in HILIC (hydrophilic interaction liquid chromatography) mode. The sample preparation included a clean-up step with hexane for the removal of lipophilic compounds and then protein precipitation with organic solvent. Results: The achieved low limits of quantification in blood were 0.25 ng/mL for TFV, and 0.5 ng/mL for TFVDP. Linearity, accuracy (91.63–109.18%), precision (2.48–14.08), and stability were validated for whole blood matrix, meeting the guidelines performance criteria. Samples collected from treated patients were analyzed, with results being in accordance with the reported pharmacokinetics. Conclusions: The new method is adequate for analyzing samples in a clinical set-up. The measurement of both TFV and TFVDP improves clinical decision by an in-depth evaluation of long-term adherence, and together with viral load and resistance data helps guiding the treatment towards the intended virological suppression. Full article

Background: Statin intolerance is a serious therapeutic dilemma in secondary cardiovascular prevention (e.g., ESC/EAS Guidelines 2023). This is especially true when confirmed by genetic predisposition and complicated by rhabdomyolysis. Although several non-statin agents have become available in recent years, evidence regarding their combined use in high-risk statin-intolerant patients remains limited. Furthermore, the pharmacokinetics of statins in toxic concentrations are poorly characterized in clinical settings. Case Presentation: We present two cases of genetically confirmed statin-induced rhabdomyolysis, both accompanied by severe acute kidney injury requiring renal replacement therapy. In both patients, serial measurements of rosuvastatin plasma concentrations revealed markedly delayed elimination, with detectable levels persisting for several weeks despite ongoing dialysis. Estimated half-lives exceeded 7 days in both cases, far beyond the known therapeutic range. Genetic testing identified SLCO1B1, ABCB1, and CYP2C9 polymorphisms linked to reduced hepatic uptake and impaired drug clearance. Following biochemical recovery, both patients were initiated on a triple non-statin lipid-lowering regimen consisting of ezetimibe, bempedoic acid, and inclisiran. The combination was well tolerated, with no recurrence of muscle-related symptoms or biochemical toxicity. LDL-C levels were reduced from 3.05 to 1.59 mmol/L and from 4.99 to 1.52 mmol/L, respectively, with sustained response over 12 and 40 weeks. Full lipid profiles demonstrated favorable changes across all parameters. Conclusions: These two cases suggest that the combination of ezetimibe, inclisiran, and bempedoic acid may serve as a safe and effective therapeutic option in patients with severe statin intolerance. Pharmacogenetic testing and serial pharmacokinetic assessment may guide personalized lipid-lowering strategies and improve outcomes in this challenging patient population. Full article

Direct oral anticoagulants (DOACs) have emerged as a preferred alternative to vitamin K antagonists (VKAs) for the prevention and treatment of thromboembolic disorders, offering improved safety, predictable pharmacokinetics, and ease of administration. Despite these advantages, their use in complex clinical scenarios presents significant challenges that necessitate individualized therapeutic strategies. This comprehensive review explores the efficacy, safety, and limitations of DOAC therapy in special populations, including patients with renal or hepatic impairment, obesity, cancer-associated thrombosis, and antiphospholipid syndrome. Additionally, we examine their role in uncommon thrombotic conditions such as superficial venous thrombosis, embolic stroke of undetermined source, upper extremity vein thrombosis, inferior vena cava thrombosis, pelvic vein thrombosis, and cerebral vein thrombosis. The pharmacokinetic variability of DOACs in renal and hepatic dysfunction requires caution to balance the bleeding and thrombotic risks. In obesity, altered drug distribution and metabolism raise concerns regarding appropriate dosing and therapeutic efficacy. Cancer-associated thrombosis presents a complex interplay of prothrombotic mechanisms, necessitating careful selection of anticoagulant therapy. Furthermore, the use of DOACs in antiphospholipid syndrome remains controversial due to concerns about recurrent thrombotic events. Finally, in some unusual scenarios like inferior vena cava, pelvic vein, and cerebral vein thrombosis, the use of DOACs has scarce evidence. This review aims to guide clinicians in optimizing anticoagulation management in challenging patient populations by synthesizing current evidence and providing practical recommendations. Full article

Background: Candesartan cilexetil, a Biopharmaceutics Classification System (BCS) II prodrug, demonstrates compromised bioavailability attributable to its limited aqueous solubility coupled with P-glycoprotein (P-gp)-mediated efflux and hepatic first-pass metabolism, thereby introducing complexities in generic drug bioequivalence assessments. With the rapid advancement of computational technologies, the integration of biorelevant dissolution methodologies with physiologically based pharmacokinetic (PBPK) modeling is emerging as a transformative paradigm in advancing bioequivalence evaluation strategies for generic drug products. This study presents a GastroPlus^®-driven framework integrating in vivo predictive dissolution (IPD) and virtual bioequivalence (VBE) to evaluate the quality consistency of generic candesartan cilexetil tablets. Methods: By developing an oral PBPK model in GastroPlus^®, we established an IPD method using a phosphate-buffer-based flow-through cell dissolution apparatus. In vitro dissolution profiles of generic tablets from four manufacturers were measured and incorporated into the model to perform VBE simulations. Results: The results demonstrated that only the product from Company A achieved virtual bioequivalence with the reference product, aligning with real-world quality consistency assessments. Conclusions: The proposed framework exhibited robust predictive capability, bridging in vitro dissolution data to in vivo bioequivalence outcomes, thereby offering a cost-effective and efficient strategy for formulation optimization and preclinical bioequivalence evaluation of generic drugs. Full article

Background: Despite the well-established liver-protective efficacy of monoammonium glycyrrhizinate (MONO), diammonium glycyrrhizinate (DIAM), and magnesium isoglycyrrhizinate (MAGN), which has been translated into clinical practice, their clinical differentiation remains elusive owing to their structural similarities and overlapping therapeutic effects. Methods: The present study delves into the pharmacokinetics, cellular-level liver-protective potencies, and underlying mechanisms of action of these three compounds through a comprehensive analysis. Results: The findings reveal that both DIAM and MAGN exhibit superior bioavailability and hepatoprotective profiles compared to MONO. Notably, an investigation of the metabolic pathways mediating liver protection in normal human liver cells (LO2), utilizing an ultra-performance liquid chromatography–time of flight tandem mass spectrometry (UPLC-TOF-MS/MSe) platform, demonstrated that MAGN augments antioxidant components, thereby favoring its application in drug-induced liver injury (DILI). Conversely, DIAM appears to be a more suitable candidate for addressing non-alcoholic fatty liver disease (NAFLD) and viral hepatitis. Conclusion: This study contributes novel perspectives on the mechanisms of action and potential clinical utilities of DIAM and MAGN in liver disease prevention and management. Full article

Background: Psilocybin has shown promise in therapeutic applications for mental disorders. Understanding the pharmacokinetics of psilocybin and its active metabolite psilocin is crucial for optimizing its clinical use and minimizing adverse effects. Methods: This systematic review involved a comprehensive search across MEDLINE, APA PsycINFO, and Embase databases, from inception to December 2024, identifying original studies that investigated the pharmacokinetics of psilocybin. Results: Fourteen studies met the inclusion criteria: eight laboratory-based and six clinical studies. Laboratory studies used animal models or in vitro systems, while clinical studies included 112 healthy human participants. Psilocybin is rapidly dephosphorylated to psilocin, which is absorbed with Tmax values ranging from 1.8 to 4 h following oral administration. Cmax varied dose-dependently, from 8.2 ± 2.8 ng/mL (plasma) to 871 ng/mL (urine). One study reported psilocin bioavailability at 52.7 ± 20%. The volume of distribution was extensive, ranging from 277 ± 92 L to 1016 L, suggesting significant tissue distribution. Psilocin metabolism is primarily mediated by CYP2D6 and CYP3A4, with secondary contributions from monoamine oxidase A. It undergoes further hepatic biotransformation into 4-hydroxyindole-3-acetic acid and 4-hydroxytryptophol. Elimination half-life varied across studies, ranging from 1.5 to 4 h. Conclusions: Psilocybin pharmacokinetics demonstrate significant variability based on dosage, route, and species. CYP enzymes play a critical role in its metabolism, highlighting the potential for drug–drug interactions. These findings underscore the importance of further research to elucidate psilocybin’s pharmacokinetic profile, which is assessed in vivo by its active metabolite psilocin. Full article

Background: Tofacitinib is mainly used in the adult population for immune-mediated inflammatory diseases. There is little information available on the pharmacokinetics of tofacitinib in pediatric patients, populations with hepatic impairment and renal impairment, and patients with drug–drug interactions (DDIs). This study aimed to develop a physiologically based pharmacokinetic (PBPK) model to predict the pharmacokinetics of tofacitinib in the populations mentioned above. Methods: We developed the PBPK models in PK-Sim^® and evaluated the models with observed clinical PK data. The Monte Carlo algorithm was used for parameter identification. Results: The adult PBPK model accurately simulated the pharmacokinetic profiles of all administration scenarios. The geometric mean fold errors for the predicted/observed maximum concentration and area under the curve are 1.17 and 1.16, respectively. The extrapolated models accurately simulated the pharmacokinetic characteristics of tofacitinib. The pediatric patients aged 12-to-<18 years and 2-to-<6 years need to adjust the dose to 4 mg BID and 1.7 mg BID, respectively, to achieve comparable steady-state exposures to 5 mg BID in adults. The populations with moderate hepatic impairment and severe renal impairment need to reduce the dose to 50% and 75% of the original dose, respectively. Tofacitinib should be reduced to 50% and 65% of the original dose for concomitant use with fluconazole and ketoconazole, respectively, and increased to 150% of the original dose for concomitant use with rifampicin. Conclusions: We developed a tofacitinib PBPK model and extrapolated it to special populations and DDIs. The predictive results of the models can help the rational use of tofacitinib in these populations. Full article

Background/Objectives: Infliximab, ipilimumab, and nivolumab are three monoclonal antibodies that have been associated with hepatotoxicity. Three separate physiologically based pharmacokinetic (PBPK) models were developed in GastroPlus^® to simulate plasma and liver concentrations in patient populations after administration of either infliximab, ipilimumab, or nivolumab. Methods: The models include distribution and clearance mechanisms specific to large molecules, FcRn binding dynamics, and target-mediated drug disposition (TNF-α for infliximab, CTLA-4 for ipilimumab, and PD-1 for nivolumab). Results: The PBPK model for each large molecule was able to reproduce observed plasma concentration data in patient populations, including patients with rheumatoid arthritis and patients with solid tumors. Liver concentrations were predicted to be between 10% and 23% of the plasma concentrations for each of the three drugs, aligning with previously reported results. This lends further validity to the PBPK models and their ability to accurately predict hepatic concentrations in the absence of direct tissue measurements. Conclusions: These results can be used to drive liver toxicity predictions using the quantitative systems toxicology model, BIOLOGXsym™, which integrates hepatic interstitial concentrations with in vitro mechanistic toxicity data to predict the extent of liver toxicity for biologics. Full article

Background: Hepatitis D virus (HDV) is a defective virus requiring co-infection with hepatitis B virus (HBV) to replicate, occurring in 5% of HBV+ patients. Bulevirtide (BLV) is now the first-in-class specific anti-HDV agent, inhibiting HDV binding to NTCP, with good tolerability and good virological and biochemical response rates. Currently, little is known about its pharmacokinetic/pharmacodynamic (PK/PD), as well as potential drug-drug interaction (DDI) profile. In this work we provide a systematic review of the current knowledge on these aspects. Methods: A literature review of PK, PD and DDI profiles of BLV was conducted from Pubmed and EMA websites. Experimentally tested interactions and hypothetical mechanisms of interaction were evaluated, mostly focusing on usually co-administered anti-infective agents and other drugs interacting on NTCP. Results: BLV shows non-linear PK, due to target-mediated drug disposition, so its PK as well as PD is expected to be influenced by interactions of other drugs with NTCP, while it is not substrate of CYPs and ABC transporters. In-vivo investigated DDIs showed no clinically relevant interactions, but a weak inhibitory effect was suggested on CYP3A4 in a work when used at high doses (10 mg instead of 2 mg). In vitro, a weak inhibitory effect on OATP transporters was observed, but at much higher concentrations than the ones expected in vivo. Conclusions: The drug-drug interaction potential of BLV can be considered generally very low, particularly at the currently approved dose of 2 mg/day. Some attention should be paid to the coadministration of drugs with known binding and/or inhibition of NTCP. Full article