SciCombinator

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Concept: Pharmacokinetics

412

We propose that highly processed foods share pharmacokinetic properties (e.g. concentrated dose, rapid rate of absorption) with drugs of abuse, due to the addition of fat and/or refined carbohydrates and the rapid rate the refined carbohydrates are absorbed into the system, indicated by glycemic load (GL). The current study provides preliminary evidence for the foods and food attributes implicated in addictive-like eating.

Concepts: Addiction, Glycemic index, Glycemic load, Drug addiction, Pharmacokinetics, Food, Carbohydrate, Nutrition

168

We investigated flexible liposomes as a potential oral drug delivery system. However, enhanced membrane fluidity and structural deformability may necessitate liposomal surface modification when facing the harsh environment of the gastrointestinal tract. In the present study, silica-coated flexible liposomes loaded with curcumin (CUR-SLs) having poor water solubility as a model drug were prepared by a thin-film method with homogenization, followed by the formation of a silica shell by the sol-gel process. We systematically investigated the physical properties, drug release behavior, pharmacodynamics, and bioavailability of CUR-SLs. CUR-SLs had a mean diameter of 157 nm and a polydispersity index of 0.14, while the apparent entrapment efficiency was 90.62%. Compared with curcumin-loaded flexible liposomes (CUR-FLs) without silica-coatings, CUR-SLs had significantly higher stability against artificial gastric fluid and showed more sustained drug release in artificial intestinal fluid as determined by in vitro release assays. The bioavailability of CUR-SLs and CUR-FLs was 7.76- and 2.35-fold higher, respectively, than that of curcumin suspensions. Silica coating markedly improved the stability of flexible liposomes, and CUR-SLs exhibited a 3.31-fold increase in bioavailability compared with CUR-FLs, indicating that silica-coated flexible liposomes may be employed as a potential carrier to deliver drugs with poor water solubility via the oral route with improved bioavailability.

Concepts: Medicinal chemistry, Digestion, Pharmacology, Sol-gel, Biopharmaceutics Classification System, Pharmacokinetics, Membrane biology, Drugs

168

OBJECTIVES: To determine the mycophenolic acid pharmacokinetic profile early after transplant in Iranian kidney graft recipients. MATERIALS AND METHODS: A cross-sectional study was performed during 6 months in 31 patients who recently had kidney transplant and received fixed doses of mycophenolate mofetil (2 g/d). The plasma levels of mycophenolic acid were determined by high performance liquid chromatography. RESULTS: The mean first mycophenolic acid peak level was 10 ± 5 mg/L. The mean mycophenolic acid area under the curve was 26 ± 19 mgh/L and apparent clearance was 57 ± 55 L/h. The mycophenolic acid area under the curve values of only 8 patients (26%) were within the therapeutic range (30-60 mgh/L). The first, second, and third mycophenolic acid peak levels correlated significantly with mycophenolic acid area under the curve (P < .05). Mycophenolic acid concentration at 10 hours had the highest correlation with mycophenolic acid area under the curve (r=0.962; P < .05). No statistically significant differences were evident in the mean mycophenolic acid area under the curve between men and women. CONCLUSIONS: There was a high degree of variation between different patients in mycophenolic acid pharmacokinetics early after kidney transplant.

Concepts: Statistics, Statistical significance, Kidney transplantation, Pharmacokinetics, High performance liquid chromatography, Pharmacology, Mycophenolate mofetil, Mycophenolic acid

168

The disposition of ertugliflozin (PF-04971729), an orally active selective inhibitor of the sodium-dependent glucose cotransporter 2, was studied after a single 25-mg oral dose of [(14)C]-PF-04971729 to healthy human subjects. Mass balance was achieved with approximately 91% of the administered dose recovered in urine and feces. The total administered radioactivity excreted in feces and urine was 40.9% and 50.2%, respectively. The absorption of PF-04971729 in humans was rapid with a T(max) at ~ 1.0 h. Of the total radioactivity excreted in feces and urine, unchanged PF-04971729 collectively accounted for ~ 35.3% of the dose, suggestive of moderate metabolic elimination in humans. The principal biotransformation pathway involved glucuronidation of the glycoside hydroxyl groups to yield three regioisomeric metabolites M4a, M4b and M4c (~39.3% of the dose in urine) of which M4c was the major regioisomer (~31.7% of the dose). The structure of M4a and M4c were confirmed to be PF-04971729-4-O-β- and -3-O-β-glucuronide, respectively, via comparison of the HPLC retention time and mass spectra with authentic standards. A minor metabolic fate involved oxidation by cytochrome P450 to yield monohydroxylated metabolites M1 and M3 and des-ethyl PF-04971729 (M2), which accounted for ~5.2% of the dose in excreta. In plasma, unchanged PF-04971729 and the corresponding 4-O-β- (M4a) and 3-O-β- (M4c) glucuronides were the principal components, which accounted for 49.9, 12.2 and 24.1% of the circulating radioactivity. Overall, these data suggest that PF-04971729 is well absorbed in humans, and eliminated largely via glucuronidation.

Concepts: Steroid, Pharmacokinetics, Alcohol, Excretion, Nutrition, Carbohydrate, Cytochrome P450, Metabolism

164

MMilk thistle (Silybum marianum) extracts, one of the most widely used dietary supplements, contain a mixture of six major flavonolignans (silybin A, silybin B, isosilybin B, isosilybin A, silychristin, and silydianin) and other components. However, the pharmacokinetics of the free individual flavonolignans has only partially been investigated in humans. Further, antioxidant effects of the extract, which may underlie the basis of many therapeutic effects, have not been thoroughly assessed. The present study was to evaluate the pharmacokinetics of the six major flavonolignans in healthy volunteers receiving single doses either one(175 mg), two(350 mg), or three(525 mg) of milk thistle capsule(s) on three separate study visits. Additionally, the steady state pharmacokinetic parameters were determined after the subjects were administered one capsule thrice daily for 28 consecutive days. Our results demonstrated that all six flavonolignans were rapidly absorbed and eliminated. In order of abundance, the exposure to free flavonolignans was greatest for silybin A followed by silybin B, isosilybin B, isosilybin A, silychristin, and silydianin. The systemic exposure to these compounds appeared linear and dose-proportional. The disposition of flavonolignans was stereoselective, as evidenced by the apparent clearance of silybin B, which was significantly greater than silybin A, whereas the apparent clearance of isosilybin B was significantly lower than isosilybin A. The concentrations of urinary 8-epi-prostaglandin F2α, a commonly used biomarker of oxidative status in humans, were considerably decreased in study subjects after a 28-day exposure to the extract (1.3±0.9 versus 0.8±0.9 ng/mg creatinine), but failed to reach statistical significance (P=0.076).

Concepts: Pharmacokinetics, Therapeutic effect, Flavonolignan, Amanita phalloides, Milk thistle, Antioxidant, Silibinin, Silybum marianum

149

To develop a comprehensive computational framework to simulate tissue distribution of gold nanoparticles (AuNP) across several species.

Concepts: Pharmacokinetics, Distribution, Nanotechnology, Nanoparticle, Gold

34

Background BTH1677 is a beta glucan pathogen associated molecular pattern (PAMP) currently being investigated as a novel cancer therapy. Here, the initial safety and pharmacokinetic (PK) results of BTH1677 in healthy subjects are reported. Subjects and Methods In the Phase 1a single-dosing study, subjects were randomized (3:1 per cohort) to a single intravenous (iv) infusion of BTH1677 at 0.5, 1, 2, 4, or 6 mg/kg or placebo, respectively. In the Phase 1b multi-dosing study, subjects were randomized (3:1 per cohort) to 7 daily iv infusions of BTH1677 at 1, 2, or 4 mg/kg or placebo, respectively. Safety and PK non-compartmental analyses were performed. Results Thirty-six subjects (N = 24 Phase 1a; N = 12 Phase 1b) were randomized to treatment. No deaths or serious adverse events occurred in either study. Mild or moderate adverse events (AEs) occurred in 67 % of BTH1677-treated subjects in both studies. Treatment-related AEs (occurring in ≥10 % of subjects) included dyspnea, flushing, headache, nausea, paraesthesia, and rash in Phase 1a and conjunctivitis and headache in Phase 1b. BTH1677 serum concentration was linear with dose. Clearance, serum elimination half-life (t1/2) and volume of distribution (Vss) were BTH1677 dose-independent. In Phase 1b, area under the curve, t1/2, and Vss values were larger at steady state on days 6-30 versus day 0. Conclusions BTH1677 was well tolerated after single doses up to 6 mg/kg and after 7 daily doses up to 4 mg/kg.

Concepts: Steady state, Half-life, Dose, Thermodynamics, Acupuncture, Clinical trial, Pharmacokinetics, Pharmacology

34

The cholesterol-lowering blockbuster drug pravastatin can be produced by stereoselective hydroxylation of the natural product compactin. We report here the metabolic reprogramming of the antibiotics producer Penicillium chrysogenum toward an industrial pravastatin production process. Following the successful introduction of the compactin pathway into the β-lactam-negative P. chrysogenum DS50662, a new cytochrome P450 (P450 or CYP) from Amycolatopsis orientalis (CYP105AS1) was isolated to catalyze the final compactin hydroxylation step. Structural and biochemical characterization of the WT CYP105AS1 reveals that this CYP is an efficient compactin hydroxylase, but that predominant compactin binding modes lead mainly to the ineffective epimer 6-epi-pravastatin. To avoid costly fractionation of the epimer, the enzyme was evolved to invert stereoselectivity, producing the pharmacologically active pravastatin form. Crystal structures of the optimized mutant P450Prava bound to compactin demonstrate how the selected combination of mutations enhance compactin binding and enable positioning of the substrate for stereo-specific oxidation. Expression of P450Prava fused to a redox partner in compactin-producing P. chrysogenum yielded more than 6 g/L pravastatin at a pilot production scale, providing an effective new route to industrial scale production of an important drug.

Concepts: Pharmacokinetics, Hydrogen, Producer, Fungus, Pharmacology, Enzyme, Cytochrome P450, Metabolism

29

The efficacy of oral risperidone treatment in prevention of schizophrenia is well known. However, oral side effects and patient compliance is always a problem for schizophrenics. In this study, risperidone was formulated into matrix transdermal patches to overcome these problems. The formulation factors for such patches, including eudragit RL 100 and eudragit RS 100 as matrix forming polymers, olive oil, groundnut oil and jojoba oil in different concentrations as enhancers and amount of drug loaded were investigated. The transdermal patches containing risperidone were prepared by solvent casting method and characterized for physicochemical and in vitro permeation studies through excised rat skin. Among the tested preparations, formulations with 20% risperidone, 3:2 ERL 100 and ERS 100 as polymers, mixture of olive oil and jojoba oil as enhancer, exhibited greatest cumulative amount of drug permeated (1.87 ± 0.09 mg/cm(2)) in 72 h, so batch ROJ was concluded as optimized formulation and assessed for pharmacokinetic, pharmacodynamic and skin irritation potential. The pharmacokinetic characteristics of the optimized risperidone patch were determined using rabbits, while orally administered risperidone in solution was used for comparison. The calculated relative bioavailability of risperidone transdermal patch was 115.20% with prolonged release of drug. Neuroleptic efficacy of transdermal formulation was assessed by rota-rod and grip test in comparison with control and marketed oral formulations with no skin irritation. This suggests the transdermal application of risperidone holds promise for improved bioavailability and better management of schizophrenia in long-term basis.

Concepts: Transdermal patches, Bioavailability, In vivo, In vitro, Pharmacokinetics, Antipsychotic, Transdermal patch, Pharmacology

29

AIM: This study examined the effects of grapefruit juice on the new P2Y(12) inhibitor ticagrelor, which is a substrate of CYP3A4 and P-glycoprotein. METHODS: In a randomized crossover study, ten healthy volunteers ingested 200 ml of grapefruit juice or water thrice daily for four days. On day three, they ingested a single 90-mg dose of ticagrelor. RESULTS: Grapefruit juice increased ticagrelor geometric mean peak plasma concentration (C(max) ) to 165% (95% confidence interval, 147-184%) and area under the concentration-time curve (AUC(0-∞) ) to 221% of control (95% confidence interval, 200-245%). The C(max) and AUC(0-34h) (P < 0.05) but not the AUC(0-∞) of the active metabolite C12490XX were decreased significantly. Grapefruit juice had a minor effect on ticagrelor elimination half-life prolonging it from 6.7 to 7.2 h (P = 0.036). In good correlation with the elevated plasma ticagrelor concentrations, grapefruit juice enhanced the antiplatelet effect of ticagrelor, assessed with VerifyNow® and Multiplate® methods, and postponed the recovery of platelet reactivity. CONCLUSIONS: Grapefruit juice increased ticagrelor exposure by more than two-fold, leading to an enhanced and prolonged ticagrelor antiplatelet effect. The grapefruit juice-ticagrelor interaction seems clinically important and indicates the significance of intestinal metabolism to ticagrelor pharmacokinetics.

Concepts: Effect, Pharmacokinetics, Grapefruit, Statistical hypothesis testing, Interval finite element, Statistics, Crossover study, Pharmacology