Phytochemicals That Interfere With Drug Metabolism and Transport, Modifying Plasma Concentration in Humans and Animals.

Phytochemicals (Pch) present in fruits, vegetables and other foods, are known to inhibit or induce drug metabolism and transport. An exhaustive search was performed in five databases covering from 2000 to 2021. Twenty-one compounds from plants were found to modulate CYP3A and/or P-gp activities and modified the pharmacokinetics and the therapeutic effect of 27 different drugs. Flavonols, flavanones, flavones, stilbenes, diferuloylmethanes, tannins, protoalkaloids, flavans, hyperforin and terpenes, reduce plasma concentration of cyclosporine, simvastatin, celiprolol, midazolam, saquinavir, buspirone, everolimus, nadolol, tamoxifen, alprazolam, verapamil, quazepam, digoxin, fexofenadine, theophylline, indinavir, clopidogrel. Anthocyanins, flavonols, flavones, flavanones, flavonoid glycosides, stilbenes, diferuloylmethanes, catechin, hyperforin, alkaloids, terpenes, tannins and protoalkaloids increase of plasma concentration of buspirone, losartan, diltiazem, felodipine, midazolam, cyclosporine, triazolam, verapamil, carbamazepine, diltiazem, aripiprazole, tamoxifen, doxorubicin, paclitaxel, nicardipine. Interactions between Pchs and drugs affect the gene expression and enzymatic activity of CYP3A and P-gp transporter, which has an impact on their bioavailability; such that co-administration of drugs with food, beverages and food supplements can cause a subtherapeutic effect or overdose. Therefore, it is important for the clinician to consider these interactions to obtain a better therapeutic effect.

Comparative Bioavailability and Pharmacokinetics Between the Solid Form of Metformin vs a Novel Liquid Extemporaneous Formulation in Children.

Metformin pharmacokinetics in a liquid extemporaneous formulation from commercial tablets was determined in paediatric patients. A randomized, transversal clinical trial was conducted in 34 children and adolescents between 7 and 17 years of age. 17 children were randomized to take metformin in the liquid formulation and, after a 1-week wash period, a 500 mg metformin tablet was administered to them. Blood samples were obtained in Whatman 903® cards at 0, 1, 2, 4, 8, 12 and 24 hours. Extraction was made by direct precipitation with acetonitrile (ACN) and methanol, detection by UPLC and tandem mass spectrometry. The method was accurate, precise, selective and linear from 50 to 1000 ng/mL (r = .9982). Comparative pharmacokinetics, tablet vs formulation, were as follows: Cmax 1503.2 ng/mL vs 1521.4, Tmax 1.5 h vs 2.3, and half-life 8.2 vs 7.5 h. The liquid formulation of metformin showed similar pharmacokinetics to the tablet, and the ratios (90% CI) of geometric mean for metformin were 100.63% (89.13-113.6), 98.08% (88.04-109.2), and 97.52% (84.9-112.01), for Cmax, AUC0-t, and AUC 0-∞, respectively. Pharmacokinetics was determined using WinNonlin Pro 3.1 software. The liquid formulation of metformin showed similar pharmacokinetics to the tablet, allowing a more precise dose adjustment and ease of administration.

The L125F MATE1 variant enriched in populations of Amerindian origin is associated with increased plasma levels of metformin and lactate.

Genetic factors that affect variability in metformin response have been poorly studied in the Latin American population, despite its being the initial drug therapy for type 2 diabetes, one of the most prevalent diseases in that region. Metformin pharmacokinetics is carried out by members of the membrane transporters superfamily (SLCs), being the multidrug and toxin extrusion protein 1 (MATE1), one of the most studied. Some genetic variants in MATE1 have been associated with reduced in vitro metformin transport. They include rs77474263 p.[L125F], a variant present at a frequency of 13.8% in Latin Americans, but rare worldwide (less than 1%). Using exome sequence data and TaqMan genotyping, we revealed that the Mexican population has the highest frequency of this variant: 16% in Mestizos and 27% in Amerindians, suggesting a possible Amerindian origin. To elucidate the metformin pharmacogenetics, a children cohort was genotyped, allowing us to describe, for the first time, a MATE1 rs77474263 TT homozygous individual. An additive effect of the L125F variant was observed on blood metformin accumulation, revealing the highest metformin and lactate serum levels in the TT homozygote, and intermediate metformin values in the heterozygotes. Moreover, a molecular dynamics analysis suggested that the genetic variant effect on metformin efflux could be due to a decreased protein permeability. We conclude that pharmacogenetics could be useful in enhancing metformin pharmacovigilance in populations having a high frequency of the risk genotype, especially considering that these populations also have a higher susceptibility to the diseases for which metformin is the first-choice drug.

Determination of blood dexmedetomidine in dried blood spots by LC-MS/MS to screen therapeutic levels in paediatric patients.

Dexmedetomidine is an imidazole derivative, with high affinity for α2 adrenergic receptors, used for sedation, analgesia and adjuvant anaesthesia. In this study, an analytical method for the quantification of dexmedetomidine in dried blood spots was developed, validated and applied. The drug was extracted from dried blood spot by liquid extraction; the separation was carried out by ultra high-resolution liquid chromatography in reverse phase coupled to tandem mass spectrometry method. An X Select cyano 5 µm HSS column (2.1 X 150 mm, Waters) and a mobile phase composed of 0.1% formic acid: acetonitrile [50:50 v/v], were used. The test was linear over the concentration range of 50 to 2000 pg/mL. The coefficients of variation for the intra and interday trials were less than 15%. The drug was stable under the conditions tested. The method was successfully applied for the quantification of 6 patients, aged 0 to 2 years, with classification ASA I, who underwent ambulatory surgeries, receiving a dose of 1 µg/Kg dexmedetomidine IV. The drug concentrations in the different sampling times were in the range of 76 to 868 pg/mL.

Population Pharmacokinetics and Pharmacodynamics of Dexmedetomidine in Children Undergoing Ambulatory Surgery.

BACKGROUND: Dexmedetomidine (DEX) is an α-2 adrenergic agonist with sedative and analgesic properties. Although not approved for pediatric use by the Food and Drug Administration, DEX is increasingly used in pediatric anesthesia and critical care. However, very limited information is available regarding the pharmacokinetics of DEX in children. The aim of this study was to investigate DEX pharmacokinetics and pharmacodynamics (PK-PD) in Mexican children 2-18 years of age who were undergoing outpatient surgical procedures. METHODS: Thirty children 2-18 years of age with American Society of Anesthesiologists physical status score of I/II were enrolled in this study. DEX (0.7 µg/kg) was administered as a single-dose intravenous infusion. Venous blood samples were collected, and plasma DEX concentrations were analyzed with a combination of high-performance liquid chromatography and electrospray ionization-tandem mass spectrometry. Population PK-PD models were constructed using the Monolix program. RESULTS: A 2-compartment model adequately described the concentration-time relationship. The parameters were standardized for a body weight of 70 kg by using an allometric model. Population parameters estimates were as follows: mean (between-subject variability): clearance (Cl) (L/h × 70 kg) = 20.8 (27%); central volume of distribution (V1) (L × 70 kg) = 21.9 (20%); peripheral volume of distribution (V2) (L × 70 kg) = 81.2 (21%); and intercompartmental clearance (Q) (L/h × 70 kg) = 75.8 (25%). The PK-PD model predicted a maximum mean arterial blood pressure reduction of 45% with an IC50 of 0.501 ng/ml, and a maximum heart rate reduction of 28.9% with an IC50 of 0.552 ng/ml. CONCLUSIONS: Our results suggest that in Mexican children 2-18 years of age with American Society of Anesthesiologists score of I/II, the DEX dose should be adjusted in accordance with lower DEX clearance.

Baclofen in the Therapeutic of Sequele of Traumatic Brain Injury: Spasticity.

Traumatic brain injury (TBI) is an alteration in brain function, caused by an external force, which may be a hit on the skull, rapid acceleration or deceleration, penetration of an object, or shock waves from an explosion. Traumatic brain injury is a major cause of morbidity and mortality worldwide, with a high prevalence rate in pediatric patients, in which treatment options are still limited, not available at present neuroprotective drugs. Although the therapeutic management of these patients is varied and dependent on the severity of the injury, general techniques of drug types are handled, as well as physical and surgical. Baclofen is a muscle relaxant used to treat spasticity and improve mobility in patients with spinal cord injuries, relieving pain and muscle stiffness. Pharmacological support with baclofen is contradictory, because disruption of its oral administration may cause increased muscle tone syndrome and muscle spasm, prolonged seizures, hyperthermia, dysesthesia, hallucinations, or even multisystem organ failure. Combined treatments must consider the pathophysiology of broader alterations than only excitation/inhibition context, allowing the patient's reintegration with the greatest functionality.

A New Method to Quantify Ifosfamide Blood Levels Using Dried Blood Spots and UPLC-MS/MS in Paediatric Patients with Embryonic Solid Tumours.

Ifosfamide blood concentrations are necessary to monitor its therapeutic response, avoiding any adverse effect. We developed and validated an analytical method by UPLC-MS/MS to quantify ifosfamide in dried blood spots (DBS). Blood samples were collected on Whatman 903® filter paper cards. Five 3 mm disks were punched out from each dried blood spot. Acetonitrile and ethyl acetate were used for drug extraction. Chromatographic separation was carried out in an Acquity UPLC equipment with a BEH-C18 column, 2.1 x 100 mm, 1.7 µm (Waters®). The mobile phase consisted in 5 mM ammonium formate and methanol:acetonitrile (40:48:12 v/v/v) at 0.2 mL/min. LC-MS/MS detection was done by ESI+ and multiple reaction mode monitoring, ionic transitions were m/z1+ 260.99 > 91.63 for ifosfamide and 261.00 > 139.90 for cyclophosphamide (internal standard). This method was linear within a 100-10000 ng/mL range and it was accurate, precise and selective. Ifosfamide samples in DBS were stable for up to 52 days at -80°C. The procedure was tested in 14 patients, ages 1 month to 17 years (9 males and 5 females), with embryonic tumours treated with ifosfamide, alone or combined, at a public tertiary referral hospital. Ifosfamide blood levels ranged from 11.1 to 39.7 µmol/L at 12 hours after the last infusion, while 24-hour levels ranged from 0.7-19.7 µmol/L. The median at 12 hours was 19.5 µmol/L (Q25 14.4-Q75 29.0) and 3.8 µmol/L (Q25 1.5-Q75 9.9) at 24 hours, p<0.001. This method is feasible to determine ifosfamide plasma levels in paediatric patients.

Extemporaneous Formulations of Metformin for Pediatric Endocrinology: Physicochemical Integrity, Cytotoxicity of Sweeteners, and Quantitation of Plasma Levels.

PURPOSE: In response to the lack of pediatric formulations of metformin to control type 2 diabetes mellitus, hyperinsulinemic obesity, and dyslipidemias, we developed liquid formulations of metformin by dissolving 3 generic brands of 500-mg metformin(*,)(†,)(‡) tablets in water sweetened with sucralose. The physicochemical stabilities of these drugs were assessed and compared with those of formulations made with the innovative brand of metformin.(∥) A method to measure metformin plasma levels was proposed and then tested in 2 healthy subjects. This method may be useful to survey treatment compliance in the future. The biological safety profiles of the metformin solutions were assessed preliminarily in a system of hormone-dependent cancer cells (human breast cancer MCF-7 cells). METHODS: Metformin solutions stored at 25°C exposed to light and at 25°C, 4°C, and 40°C protected from light, underwent physicochemical analysis by ultra-performance liquid chromatography with ultraviolet detection, the mobile phase consisting of 0.2 M potassium monobasic phosphate (pH 6.5), 4.6 mM sodium dodecyl sulphate (SDS), and acetonitrile (63:7:30) at a flow rate of 0.8 mL/min in a Symmetry C8 150 × 4.6 mm column (Milford, Massachusetts) at 40°C (236 nm). MCF-7 cells were grown in 96-well ELISA plates (2 × 10(5) cells/well) and were exposed to 10, 20, and 40 mg/mL sucralose(§), Stevia rebaudiana (Svetia; Metco, S.A. de C.V., México, D.F., Mexico), and metformin (50 mg/mL) for 48 hours. Cytotoxicity was determined using the WST-1 colorimetric assay (Roche, USA) in an Epoch ELISA reader (BioTek, Winooski, Vermont) at 440 nm. FINDINGS: All brands of metformin were stable at all storage conditions for up to 30 days and retained >90% of the initial amount. Sucralose and Stevia rebaudiana caused zero cytotoxicity (ANOVA, P ≤ 0.05). The ultra-performance liquid chromatography with ultraviolet detection method was adapted to determine metformin level in very small blood samples (40 µL), which was linear within the range of 20 to 600 ng/mL metformin (retention time 2 minutes). Metformin was physically and chemically stable within the processed blood for up to 30 days at 4°C. IMPLICATIONS: Extemporaneous formulations of metformin may be developed at low cost from either the innovator or generic brands, and both sucralose and Stevia rebaudiana sweeteners may be well tolerated; however, the minimum amount of sweetener is recommended to avoid any endocrine disturbance. The analytical method is accurate and precise to clinically measure metformin levels in patients taking the extemporaneous formulation orally. Study registry identification number: 100/2013.

Genetic polymorphism of tumor necrosis factor promoter region and susceptibility to develop Hodgkin lymphoma in a Mexican population.

Hodgkin lymphoma (HL) is a rare neoplasm of the lymphatic system, in which inflammation and allelic variants in cytokines have been proposed as etiological factors. Epstein-Barr virus infection is often associated as a risk factor in HL and since cytokines are involved in the humoral response to viral infection. Our aim was to study the association between single nucleotide polymorphisms (SNPs) located in the tumor necrosis factor (TNF) gene (- 376G> A, - 238G> A and 581G> A) in a sample of Mexican patients (56 cases) and their susceptibility to develop HL, comparing these SNPs among healthy individuals (127 controls). Frequencies for TNF - 238G> A and TNF 581G> A showed no significant differences between cases and controls. However, the proportion of cases with the GA genotype of - 376 SNP showed a significant difference as compared to controls, odds ratio = 4.41 (95% confidence interval: 1.21-16.6), p = 0.02. We found that in this group of patients from Mexico the SNP - 376G> A in TNF shows an association with higher risk for HL.

Comparison between the antiproliferative effect and intracellular glutathione depletion induced by Casiopeína IIgly and cisplatin in murine melanoma B16 cells.

BACKGROUND: Casiopeína IIgly (Cas IIgly) [Cu(4,7-dimethyl-1,10-phenanthroline)(glycinate)]NO(3) induce oxidative damage in different human tumour cell strains, as the known anticancer agent cisplatin (CDDP) does. PURPOSE: To compare glutathione (GSH) depletion induced by Cas IIgly and CDDP in murine melanoma B16 cells and its relationship with their antiproliferative effect. MATERIALS AND METHODS: Cell growth was determined according to the sulforhodamine B assay. Intracellular GSH levels were measured by the reduction of Ellman's reagent (DTNB). RESULTS: Cas IIgly IC50 in B16 cells was 54.5 µM (24.21 µg/mL), which depleted GSH from 1092 to 585 ng per million cells in a 30 min incubation period. In the other hand, CDDP was less toxic at the same conditions with an IC50 equal to 197.76 µM (59.33 µg/mL), and depleted GSH to 50% of the normal only after a longer exposure period (4h). The addition of 1.8mM ascorbic acid (Asc) or 1mM buthionine sulfoximine (BSO) enhanced Cas IIgly toxicity, whereas it was prevented by 100 U/mL catalase. BSO sensitised B16 cells to CDDP, but neither Asc or catalase modified CDDP effects. CONCLUSIONS: The antiproliferative effect of both drugs correlated to intracellular GSH levels. Unlike CDDP, GSH depletion induced by Cas IIgly occurs earlier, it is enhanced by ascorbic acid and preventable by catalase. Redox cycles, feasible only with Cas IIgly, may be an important difference in their mode of action.

A reliable method of liquid chromatography for the quantification of acetaminophen and identification of its toxic metabolite N-acetyl-p-benzoquinoneimine for application in pediatric studies.

The aim of the present study was to develop a simple, selective and reliable method to quantify acetaminophen and its toxic metabolite N-acetyl-p-benzoquinoneimine (NAPQI) for pediatric studies using 100 µL plasma samples, by reverse-phase HPLC and UV detection. The assay was performed using a C18 column and an isocratic elution with water-methanol-formic acid (70:30:0.15; v/v/v) as mobile phase. Linearity of the method was assayed in the range of 1-30 µg/mL for acetaminophen and 10-200 µg/mL for NAPQI, with a correlation coefficient r = 0.999 for both compounds, and inter- and intra-day coefficients of variation of less than 13%. Several commonly co-administered drugs were analyzed for selectivity and no interference with the determinations was observed. The detection and quantification limits for acetaminophen and NAPQI were 0.1 and 1 µg/mL, and 0.1 and 10 µg/mL respectively. The present method can be used to monitor acetaminophen levels using 100 µL plasma samples, which may be helpful when very small samples need to be analyzed, as in pharmacokinetics determination or drug monitoring in plasma in children. This assay is also able to detect the NAPQI for drug monitoring in patients diagnosed with acetaminophen intoxication.

Casiopeína IIgly induced cytotoxicity to HeLa cells depletes the levels of reduced glutathione and is prevented by dimethyl sulfoxide.

The newly synthesized copper coordination compound Casiopeína IIgly (Cas IIgly) is a promising alternative drug in the treatment of cancer, since it has shown cytotoxicity and genotoxicity in different tumour models. Given its enhanced effects after ascorbic acid-mediated copper reduction, Cas IIgly's activity is thought to be related to oxidative damage. In the present work, oxidized Cas IIgly failed to induce cytosolic oxidative damage in HeLa cells (only 0.9% of the cell population), and in 2.3% of the treated cells when previously reduced, as evaluated through the oxidation of dihydrorhodamine 123 (DHR 123). However, it showed cytotoxicity, since HeLa cells treated with 10-80 microg/mL Cas IIgly proliferated only at 30% of their normal rate, and at 15% when treated with reduced Cas IIgly. This cytotoxicity is strongly abolished in the presence of the hydroxyl scavenger dimethyl sulfoxide. The decrease, from 3994 to 530 nanograms of reduced glutathione (GSH) per million cells after treatment with 80 microg/mL Casiopeína IIgly, indicates that this drug causes the expenditure of this naturally occurring antioxidant. These results altogether suggest that, albeit Cas IIgly induced cytotoxicity is not related to cytosolic DHR 123 oxidation, it may be related to oxidative damage.

Induction of oxidative damage by copper-based antineoplastic drugs (Casiopeínas).

PURPOSE: The aim of the present study is to determine in HeLa cells and in human lymphocytes, by an easy and fast method, the induction of oxidative damage to plasma membrane lipids and nuclear DNA by Casiopeínas, which are recently synthesized coordination complexes that have been considered as a promising chemotherapeutic alternative for the treatment of cancer, since they have shown cytotoxicity and genotoxicity in several cancer cell lines and xenotransplanted tumours. The presence of an oxidized copper atom in their structure strongly suggests that their mode of action seems to be related to reactive oxygen species (ROS) generation after copper atom reduction through the Fenton and Haber-Weiss system. METHOD: Lipid peroxidation was evaluated as thiobarbituric acid reactive malondialdehyde, cytotoxicity by the fluorescein diacetate/ethidium bromide stain and genotoxicity as DNA fragmentation by the comet assay. Cells were treated with ten different Casiopeínas in a concentration range higher than their IC(50) (10-100 microM), both oxidized and reduced in the presence of ascorbic acid. RESULTS: In almost all the cases, copper reduction enhanced cytotoxicity but, unlike copper nitrate used as positive control, none of them induced appreciable lipid peroxidation. Three Casiopeínas: Cas Igly, Cas-III-H-a and Cas-III-E-a, showed low, moderate and high rates of genotoxicity, respectively, and this effect was enhanced upon addition of ascorbic acid. CONCLUSION: These results suggest that ROS generation might be the cause of cytotoxicity, which seems to be related to initial genetic damage rather than to lipid peroxidation. HeLa cells showed to be more sensitive than normal cells.