Botanical extracts in combination improve autosomal recessive woolly hair/hypotrichosis caused by LIPH mutations.

BACKGROUND: Mutation in the lipase H (LIPH) gene is a main reason for autosomal recessive woolly hair (ARWH)/hypotrichosis. Although some studies reported that topical minoxidil could improve ARWH, an effective treatment method for this disease is still lacking. AIM: We attempt to explore potential treatment options for ARWH. MATERIALS & METHODS: A female 6-year-old child was diagnosed with ARWH/hypotrichosis caused by LIPH mutations. And she was treated with combined treatment of botanical extracts. RESULTS: After 6 months of treatment, the patient's hair grew remarkably. After 4 years of treatment, the patient's hair remained dense. DISCUSSION: After the combination treatment, the patient saw a favorable clinical effect. However, the specific mechanisms of action for botanical extracts require further validation. In addition, some regenerative strategies may be considered as potential treatment options for ARWH. We should actively attempt treatment for ARWH patients and encourage prenatal diagnosis due to the great impact of hair loss. CONCLUSION: The combined therapy of botanical extracts may improve ARWH long-term with a sustainable therapeutic effect.

Canagliflozin Improves Liver Function in Rats by Upregulating Asparagine Synthetase.

INTRODUCTION: Canagliflozin (CANA) is a sodium-glucose cotransporter 2 inhibitor that was recently approved for treating diabetes. However, its effects on liver function are not well understood. The function of asparagine synthetase (ASNS) has been studied in several cancers but not in liver injury. Therefore, we investigated the connection between CANA and ASNS in alleviating damage (i.e., their hepatoprotective effect) in a rat liver injury model. METHODS: The rat model of liver injury was established using carbon tetrachloride treatment. Rats with liver injury were administered CANA orally for 8 weeks daily. After week 8, peripheral blood was collected to measure serum alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase levels. Liver histopathology was examined using hematoxylin and eosin staining to determine the degree of liver injury. Protein expression in the rat livers was examined using Western blotting. RESULTS: CANA treatment decreased serum alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase levels compared with those of the untreated group, demonstrating diminished liver injury. Mechanistically, CANA treatment activated AMP-activated protein kinase (AMPK), leading to increased nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and activating transcription factor 4 (ATF4), which upregulated ASNS expression in liver-injured rats. CONCLUSION: CANA significantly alleviated liver injury by activating the AMPK/Nrf2/ATF4 axis and upregulating ASNS expression, indicating its potential for treating patients with type 2 diabetes mellitus with impaired liver function.

Physiologically Based Pharmacokinetics of Dexamethasone in Rats.

Blood and multitissue concentration-time profiles for dexamethasone (DEX), a synthetic corticosteroid, were measured in male rats after subcutaneous bolus and infusion dosing. A physiologically based pharmacokinetics (PBPK) model was applied for 12 measured tissues. Tissue partition coefficients (K p ) and metabolic clearance were assessed from infusion studies. Blood cell to plasma partitioning (0.664) and plasma free fraction (0.175) for DEX were found to be moderate. DEX was extensively partitioned into liver (K p = 6.76), whereas the calculated K p values of most tissues ranged between 0.1 and 1.5. Despite the moderate lipophilicity of DEX (log P = 1.8), adipose exhibited very limited distribution (K p = 0.17). Presumably due to P-glycoprotein-mediated efflux, DEX concentrations were very low in brain compared with its expected high permeability. Infusion studies yielded K p values from male and female rats at steady state that were similar. In silico K p values calculated for different tissues by using GastroPlus software were similar to in vivo values except for adipose and liver. Glucocorticoid receptors are found in diverse tissues, and these PBPK modeling results may help provide exposure profiles driving pharmacodynamic effects of DEX. SIGNIFICANCE STATEMENT: Our physiologically based pharmacokinetics model describes the experimentally determined tissue and plasma dexamethasone (DEX) pharmacokinetics (PK) profiles in rats reasonably well. This model can serve for further investigation of DEX tissue distribution in rats as the PK driving force for PD effects in different tissues. No major sex differences were found for DEX tissue distribution. Knowledge gained in this study may be translatable to higher-order species including humans.

Multi-stage surgery combined with radiotherapy for treatment of giant anterior chest wall keloid: A case report.

RATIONALE: Giant keloids often have indications for surgical resection, but postoperative reconstruction of the skin and high recurrence of keloids are a challenge for clinical treatment. This article reports a rare successful treatment of a giant keloid in the anterior chest wall by multistage surgery combined with radiotherapy, which is why this case is meaningful. PATIENT CONCERNS: A 66-year-old woman presented a giant keloid with ulcerations and severe itching on the anterior chest wall. She had a history of keloid disease for more than 10 years, and had been treated by multiple operations, with no success. DIAGNOSES: The patient was diagnosed as keloid based on her history and symptoms. Histopathology findings supported our diagnosis. INTERVENTIONS: We successfully excised the keloid after 5 operations and 2 rounds of electron-beam radiotherapy, which was applied at 24 hours after the 4th and 5th operation. OUTCOMES: There was no sign of recurrence over the follow-up period of 24 months. LESSONS: The combination of multistage surgery and radiotherapy presents as a good choice for the treatment of giant keloids.

Effect of Polymer Permeability and Solvent Removal Rate on In Situ Forming Implants: Drug Burst Release and Microstructure.

To explore the mechanism of drug release and depot formation of in situ forming implants (ISFIs), osthole-loaded ISFIs were prepared by dissolving polylactide, poly(lactide-co-glycolide), polycaprolactone, or poly(trimethylene carbonate) in different organic solvents, including N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), and triacetin (TA). Drug release, polymer degradation, solvent removal rate and depot microstructure were examined. The burst release effect could be reduced by using solvents exhibit slow forming phase inversion and less permeable polymers. Both the drug burst release and polymer depot microstructure were closely related to the removal rate of organic solvent. Polymers with higher permeability often displayed faster drug and solvent diffusion rates. Due to high polymer-solvent affinity, some of the organic solvent remained in the depot even after the implant was completely formed. The residual of organic solvent could be predicted by solubility parameters. The ISFI showed a lower initial release in vivo than that in vitro. In summary, the effects of different polymers and solvents on drug release and depot formation in ISFI systems were extensively investigated and discussed in this article. The two main factors, polymer permeability and solvent removal rate, were involved in different stages of drug release and depot formation in ISFI systems.

Site-specific drug delivery in the skin for the localized treatment of skin diseases.

Introduction: Due to the well-organized structure and barrier function of the skin, it is generally difficult for drugs applied directly on the surface of skin to reach their expected site of action. Accordingly, site-specific drug delivery in the skin has been increasingly explored to facilitate the treatment of skin diseases and reduce the systemic toxicity. Area covered: An overview of the generally used sites for drug delivery in the skin is herein presented. Different strategies including particle-based carriers, physical technologies, and chemical approaches are discussed with regards to their potential application in site-specific drug delivery in the skin. Expert opinion: Particle-based carriers are of particular significance for the enhancement of drug delivery in the skin. Although no recommendation can be made regarding which type of carriers can provide better skin penetration, the lipid-based colloidal systems appear to be favored due to their compatibility. In addition, the physical technologies provide unique advantages in delivering hydrophilic macromolecules for the skin immunization. As a new class of permeation enhancers, skin penetrating peptides are gaining more attention in drug delivery to skin cells. For the design of robust site-specific drug delivery systems, the impacts of diseased state and drug properties should not be disregarded.

Alteration of UDP-glucuronosyltransferase 1a1, 1a7 and P-glycoprotein expression in hepatic fibrosis rats and the impact on pharmacokinetics of puerarin.

BACKGROUND: Puerarin, derived from a traditional Chinese herb Pueraria lobata (Willd.) Ohwi which was distributed globally and planted in most parts of China, has been extensively applied in patients with cardiovascular diseases in China. Yet a considerable proportion of the patients were accompanied with liver illnesses simultaneously because of all sorts of reasons. HYPOTHESIS/PURPOSE: It had been implied by some previous research that the absorption and the metabolism of puerarin were susceptible to liver issues due to changed P-gp and Ugt1a level, but pharmacokinetics of puerarin under such conditions were few concerned. Our study aimed to make sure whether and how much the behavior of puerarin in vivo was affected by hepatic diseases, and to explore the potential mechanisms. METHODS: A CCl4 induced rat model of hepatic fibrosis (HF) was prepared and verified. Single low/high doses of oral and intravenous administration of puerarin to HF and normal rats were performed. Pharmacokinetics of puerarin were determined by a validated HPLC method. The expression of P-gp, Ugt1a1, and Ugt1a7 in both liver and intestines were determined by quantitative RT-PCR and Western blot analysis respectively. RESULTS: The systemic exposure of puerarin in HF rats of experimental groups were found decreased remarkably except for that of the high dose intravenous group. Moreover, the expression of P-gp, Ugt1a1, and Ugt1a7 in liver and intestines of HF rats were figured out increased. CONCLUSION: The results indicated that the HF originated overexpression of Ugt1a1, Ugt1a7, and P-gp level played important roles in pharmacokinetics of puerarin, suggested the clinical regimen of puerarin based on normal populations might be inappropriate for patients with chronic liver diseases. It was implied drugs whose absorption or elimination were related to P-gp, Ugt1a1, or Ugt1a7 might also be affected by hepatic illnesses.

Upregulation of UDP-Glucuronosyltransferases 1a1 and 1a7 Are Involved in Altered Puerarin Pharmacokinetics in Type II Diabetic Rats.

Puerarin is an isoflavonoid extracted from Pueraria lobata roots, and displays a broad range of pharmacological activities, including antidiabetic activity. However, information about the pharmacokinetics of puerarin in diabetics is scarce. This study was conducted to investigate the difference in pharmacokinetic effects of puerarin in normal rats and rats with diabetes mellitus (DM), and the mechanism involved. DM was induced by a combined high-fat diet (HFD) and streptozotocin (STZ) injection. Plasma concentrations of puerarin in DM, HFD, and control rats were determined after intravenous (20 mg/kg) and oral administration (500 mg/kg) of puerarin, and pharmacokinetic parameters were estimated. The messenger RNA (mRNA) and protein expression levels of Ugt1a1 and Ugt1a7 in rat livers and intestines were measured using qRT-PCR and western blot, respectively. The area under the concentration⁻time curve and the clearance of puerarin in the DM rats statistically differed from those in the control rats (p <0.05) with both administration routes. The hepatic and intestinal gene and protein expressions of Ugt1a1 and Ugt1a7 were significantly increased in the DM rats (p <0.05). Therefore, the metabolic changes in diabetes could alter the pharmacokinetics of puerarin. This change could be caused by upregulated uridine diphosphate (UDP)-glucuronosyltransferase activity, which may enhance puerarin clearance, and alter its therapeutic effects.

Plasma Pharmacokinetic Determination of Canagliflozin and Its Metabolites in a Type 2 Diabetic Rat Model by UPLC-MS/MS.

Canagliflozin is a novel, orally selective inhibitor of sodium-dependent glucose co-transporter-2 (SGLT2) for the treatment of patients with type 2 diabetes mellitus. In this study, a sensitive and efficient UPLC-MS/MS method for the quantification of canagliflozin and its metabolites in rat plasma was established and applied to pharmacokinetics in a type 2 diabetic rat model. We firstly investigated the pharmacokinetic changes of canagliflozin and its metabolites in type 2 diabetic rats in order to use canagliflozin more safely, reasonably and effectively. We identified three types of O-glucuronide metabolites (M5, M7 and M17), two kinds of oxidation metabolites (M8 and M9) and one oxidation and glucuronide metabolite (M16) using API 5600 triple-TOF-MS/MS. Following liquid⁻liquid extraction by tert-butyl methyl ether, chromatographic separation of canagliflozin and its metabolites were performed on a Waters XBridge BEH C18 column (100 × 2.1 mm, 2.5 µm) using 0.1% acetonitrile⁻formic acid (75:15, v/v) as the mobile phase at a flow rate of 0.7 mL/min. Selected ion monitoring transitions of m/z 462.00→191.10, 451.20→153.10, 638.10→191.10 and 478.00→267.00 were chosen to quantify canagliflozin, empagliflozin (IS), O-glucuronide metabolites (M5, M7 and M17), and oxidation metabolites (M9) using an API 5500-triple-MS/MS in the positive electrospray ionization mode. The validation of the method was found to be of sufficient specificity, accuracy and precision. The pathological condition of diabetes could result in altered pharmacokinetic behaviors of canagliflozin and its metabolites. The pharmacokinetic parameters (AUC0⁻t, AUC0⁻∞, CLz/F, and Vz/F) of canagliflozin were significantly different between the CTRL and DM group rats (p < 0.05 or p < 0.01), which may subsequently cause different therapeutic effects.

The longevity of tor1Δ, sch9Δ, and ras2Δ mutants depends on actin dynamics in Saccharomyces cerevisiae.

Recent studies have revealed the role of actin dynamics in the regulation of yeast aging. Although the target of rapamycin (TOR) complex, serine/threonine kinase Sch9, and Ras2 have been shown to play important roles in aging for a long time, the relationship between these regulators and actin has not yet been reported. In this study we investigated the roles of actin polarization in tor1Δ, sch9Δ, and ras2Δ mutant cells. We found that the actin structures in tor1Δ, sch9Δ, and ras2Δ mutant cells were more dynamic than those in the wild type. Destruction of the actin structures with jasplakinolide decreased the life span of tor1Δ, sch9Δ, and ras2Δ mutants. Furthermore, deletion of SLA1 in tor1Δ, sch9Δ, and ras2Δ mutants inhibited the actin dynamics and life span. In addition, we found that the actin cytoskeleton of the long-lived mutant sch9Δ, depended on the transcription factors RIM15 and MSN2/4, but not GIS1, while the actin skeleton of the tor1Δ and ras2Δ mutants depended on RIM15 as expected. Our data suggest that the longevity of tor1Δ, sch9Δ, and ras2Δ mutants is dependent on actin dynamics.

Sulfonation of curcuminoids: characterization and contribution of individual SULT enzymes.

SCOPE: Poor oral bioavailability of curcuminoids limited their various applications, and one of the main reasons is their rapid metabolism in vivo. Sulfonation via sulfotransferases (SULTs) is an important metabolic pathway for such compounds. The objective of this study is to determine the SULT-isoform-specific metabolic fingerprint, tissue-specific rate, and reaction kinetic profiles to describe the characterization and contribution of curcuminoids sulfonation. METHODS AND RESULTS: Sulfonation of curcuminoids was investigated by using nine expressed SULT isoforms and four pooled human tissue S9 fractions. The results showed that human small intestine is the predominant tissue responsible for sulfonation of curcuminoids. SULT1A3 is a major isoform catalyzing sulfonation of curcumin and demethoxycurcumin, but not for bisdemethoxycurcumin. SULT1B1 is only responsible for sulfonation of curcumin. Although SULT1C4 and 1E1 could highly catalyze the sulfate conjugations toward all the three compounds, the correlativities with human small intestine S9 fractions were much weaker (R(2) = 0.100-0.482). Almost all the kinetic profiles of the SULT isoforms for curcuminoids exhibited substrate inhibition kinetics. CONCLUSION: This investigation contributed to elucidate the SULT-mediated metabolism and detoxication of curcuminoids at molecular levels and in different organs.

Comparative pharmacokinetics study of sinomenine in rats after oral administration of sinomenine monomer and Sinomenium acutum extract.

Various products containing sinomenine monomer and extracts of Sinomenium acutum have been widely applied in clinical treatments. The goal of the present study was to compare the pharmacokinetics of sinomenine in rats after oral administration of sinomenine monomer and Sinomenium acutum extract, and to attempt to explore potential component-component interactions between the constituents of this traditional Chinese herbal medicine. A reliable and specific reversed phase high performance liquid chromatography method was developed to analyze sinomenine in rat plasma. Pharmacokinetic parameters for sinomenine were processed by non-compartmental analysis. The results showed that the maximum concentration, the area under the concentration-time curve, clearance and the apparent volume of distribution of sinomenine in the Sinomenium acutum extract statistically differed from those of sinomenine monomer (p < 0.05); however, the mean residence time, time of peak concentration, and half-life did not show significant differences between the two groups. These findings suggested that some additional components in the Sinomenium acutum extract may decrease the absorption of sinomenine. The complex interactions between sinomenine and other components of the herbal extract could result in the altered pharmacokinetic behavior of sinomenine, which may subsequently cause different therapeutic and detoxification effects.

Geochemical production of reactive oxygen species from biogeochemically reduced Fe.

The photochemical reduction of Fe(III) complexes to Fe(II) is a well-known initiation step for the production of reactive oxygen species (ROS) in sunlit waters. Here we show a geochemical mechanism for the same in dark environments based on the tidally driven, episodic movement of anoxic groundwaters through oxidized, Fe(III) rich sediments. Sediment samples were collected from the top 5 cm of sediment in a saline tidal creek in the estuary at Murrell's Inlet, South Carolina and characterized with respect to total Fe, acid volatile sulfides, and organic carbon content. These sediments were air-dried, resuspended in aerated solution, then exposed to aqueous sulfide at a range of concentrations chosen to replicate the conditions characteristic of a tidal cycle, beginning with low tide. No detectable ROS production occurred from this process in the dark until sulfide was added. Sulfide addition resulted in the rapid production of hydrogen peroxide, with maximum concentrations of 3.85 µM. The mechanism of hydrogen peroxide production was tested using a simplified three factor representation of the system based on hydrogen sulfide, Fe(II) and Fe(III). The resulting predictive model for maximum hydrogen peroxide agreed with measured hydrogen peroxide in field-derived samples at the 95% level of confidence, although with a persistent negative bias suggesting a minor undiscovered peroxide source in sediments.

SULT1A3-mediated regiospecific 7-O-sulfation of flavonoids in Caco-2 cells can be explained by the relevant molecular docking studies.

Flavonoids are polyphenolic compounds with various claimed health benefits, but the extensive metabolism by uridine-5'-diphospho-glucuronosyltransferases (UGTs) and sulfotransferases (SULTs) in liver and intestine led to poor oral bioavailabilities. The effects of structural changes on the sulfonation of flavonoids have not been systemically determined, although relevant effects of structural changes on the glucuronidation of flavonoids had. We performed the regiospecific sulfonation of sixteen flavonoids from five different subclasses of flavonoids, which are represented by apigenin (flavone), genistein (isoflavone), naringenin (flavanone), kaempherol (flavonol), and phloretin (chalcone). Additional studies were performed using 4 monohydroxyl flavonoids with a -OH group at the 3, 4', 5 or 7 position, followed by 5 dihydroxyl flavonoids, and 2 trihydroxyl flavonoids by using expressed human SULT1A3 and Caco-2 cell lysates. We found that these compounds were exclusively sulfated at the 7-OH position by SULT1A3 and primarily sulfated at the 7-OH position in Caco-2 cell lysates with minor amounts of 4'-O-sulfates formed as well. Sulfonation rates measured using SULT1A3 and Caco-2 cell lysates were highly correlated at substrate concentrations of 2.5 and 10 µM. Molecular docking studies provided structural explanations as to why sulfonation only occurred at the 7-OH position of flavones, flavonols and flavanones. In conclusion, molecular docking studies explain why SULT1A3 exclusively mediates sulfonation at the 7-OH position of flavones/flavonols, and correlation studies indicate that SULT1A3 is the main isoform responsible for flavonoid sulfonation in the Caco-2 cells.

Regioselective sulfation and glucuronidation of phenolics: insights into the structural basis.

The phase II metabolism sulfation and glucuronidation, mediated by sulfotransferases (SULTs) and UDP-glucuronosyltransferases (UGTs) respectively, are significant metabolic pathways for numerous endo-and xenobiotics. Understanding of SULT/UGT substrate specificity including regioselectivity (i.e., position preference) is of great importance in predicting contribution of sulfation/ glucuronidation to drug and metabolite disposition in vivo. This review summarizes regioselective sulfation and glucuronidation of phenolic compounds with multiple hydroxyl (OH) groups as the potential conjugation sites. The strict regioselective patterns are highlighted for several SULT and UGT isoforms towards flavonoids, a large class of natural polyphenols. To seek for a molecular-level explanation, the enzyme structures (i.e., SULT crystal structures and a homology-modeled UGT structure) combined with molecular docking are employed. In particular, the structural basis for regioselective metabolism of flavonoids by SULT1A3 and UGT1A1 is discussed. It is concluded that the regioselective nature of these phase II enzymes is determined by the size and shape of the binding pocket. While the molecular structures of the enzymes can be used to explain regioselective metabolism regarding the binding property, predicting the turnover at different positions remains a particularly difficult task.

Pharmacokinetic properties and bioequivalence of two formulations of arbidol: an open-label, single-dose, randomized-sequence, two-period crossover study in healthy Chinese male volunteers.

BACKGROUND: Arbidol is an antiviral drug indicated for the prevention and treatment of all types of influenza infection and some other kinds of acute respiratory infections, specifically against influenza groups A and B, and severe acute respiratory syndrome. It is used to help prevent influenza infection as long as necessary with little risk for influenza mutation rendering it less effective. OBJECTIVE: The aim of this study was to compare the pharmacokinetic properties and tolerability, and to determine bioequivalence, of a newly developed generic dispersible tablet formulation (test) and a branded capsule formulation (reference) of arbidol 200 mg in healthy Chinese fasted male volunteers. METHODS: This open-label, single-dose, randomized-sequence, 2-period crossover study was conducted in healthy native Chinese male volunteers. Eligible subjects were randomly assigned in a 1:1 ratio to receive a single 200-mg dose of the test or reference formulation, followed by a 1-week washout period and administration of the alternate formulation. The study drugs were administered after a 12-hour overnight fast. After the study drug administration, serial blood samples were collected for 72 hours after administration. Plasma drug concentrations were determined using high-performance liquid chromatography coupled with tandem mass spectrometry. Several pharmacokinetic pararameters, including C(max), T(max), t((1/2)), AUC(0-t), and AUC(0-infinity), were determined from the plasma concentrations of the 2 formulations of arbidol using noncompartmental analysis. The formulations were to be considered bioequivalent if the log-transformed ratios of C(max) and AUC were within the predetermined bioequivalence range of 80% to 125% established by the State Food and Drug Administration (SFDA) of the People's Republic of China. Tolerability was assessed by monitoring vital signs (blood pressure, heart rate, temperature, and electrocardiography), laboratory analysis (hematology, blood biochemistry, hepatic function, and urinalysis), and subject interview on adverse events. RESULTS: Twenty subjects were enrolled and completed the study (mean [SD] age, 21.1 [1.1] years; weight, 64.7 [5.1] kg; and height, 172.3 [3.1] cm). Neither period nor sequence effect was observed. The main pharmacokinetic properties with the test and reference formulations were as follows: C(max), 417.4 (107.6) and 414.8 (95.1) ng/mL, respectively (P = NS); median (range) T(max), 0.63 (0.25-1.0) and 0.75 (0.5-1.5) hours (P = 0.035); AUC(0-t), 2033.6 (564.9) and 1992.0 (483.3) ng/mL/h (P = NS); AUC(0-infinity), 2285.4 (597.7) and 2215.2 (604.0) ng/mL/h (P = NS); and t(1/2), 6.9 (4.2) and 6.1 (5.2) hours (P = NS). The 90% CIs for the log-transformed ratios of C(max), AUC(0-t), and AUC(0-infinity) were 91.7% to 109.7%, 91.0% to 112.8%, and 92.0% to 116.3%, respectively (all, P < 0.05), which were within the predetermined range for bioequivalence. No adverse events were found on analysis of vital signs or laboratory tests or reported by subjects in this study. CONCLUSION: In this study in healthy Chinese male volunteers, the dispersible tablet formulation and the 200-mg capsule formulation of arbidol met the SFDA's regulatory definition of bioequivalence based on the rate and extent of absorption.

Pharmacokinetics of single-dose and multiple-dose memantine in healthy chinese volunteers using an analytic method of liquid chromatography-tandem mass spectrometry.

OBJECTIVE: This study consisted of 2 phases: development of a liquid chromatography-tandem mass spectrometry (LC/MS) method for determination of memantine in human plasma and characterization of single-dose and multiple-dose pharmacokinetic profiles of memantine in healthy Chinese volunteers using the LC/MS method. METHODS: An analytic method of LC/MS for determination of memantine in human plasma was developed and validated and was applied to this single-center, open-label, single-dose and multiple-dose pharmacokinetic study conducted in healthy native Chinese volunteers. Subjects were randomized to receive a single dose of 5, 10, or 20 mg of memantine to study the linear characteristics of pharmacokinetics, or a multiple dose of 5 mg once daily for 14 days to study the drug accumulation. The pharmacokinetic parameters calculated included C(max), T(max), AUC, t(1/2),mean residence time (MRT), maximum steady-state plasma concentration (C(ssmax)), minimum steady-state plasma concentration ((ssmin)), average steady-state plasma concentration (C(ssav)), and fluctuation percentage (DF). All values were expressed as mean (SD). Sequential blood samples were collected from 0 to 360 hours for single-dose pharmacokinetic determinations after the dose on day 1; in the multiple-dose pharmacokinetic arm, the sequential blood samples were also obtained from 0 to 360 hours on day 14 after collecting the predose samples at 0 hour on days 11, 12, and 13. Memantine concentrations in plasma were determined by LC/MS method. A calibration curve was constructed by 7 memantine concentrations and processed by least-squares linear regression analysis (w=1/x(2)). Safety assessments, including adverse events (AEs), were performed at all study visits. RESULTS: The LC/MS method for determination of memantine in human plasma was developed and validated. The standard calibration curve for spiked human plasma containing memantine was linear in the concentration range of 0.2 to 200.0 ng/mL. The correlation coefficient was greater than 0.9960 (n = 6). The lower limit of quantification for memantine in human plasma was 0.2 ng/mL, and the intraday and interday coefficients of variation were all lower than 15%. The mean recoveries of the 0.4, 20.0, and 180.0 ng/mL levels were 78.87%, 81.55%, and 81.98%, respectively. The coefficients of variation were all lower than 15% after being treated at room temperature for 24 hours, for 45 days at -40 degrees , and within 3 freeze-and-thaw cycles in plasma samples. Forty native Chinese subjects (10 [5 men, 5 women] subjects per group; mean [SD] age, 21.6 [1.6] [range, 19-27] years; weight, 63.0 [7.7] [range, 52-82] kg; height, 170.0 [7.0] [range, 155-185] cm) were enrolled in the study. After single-dose oral administration, the main pharmacokinetic parameters found for memantine at doses of 5, 10, and 20 mg were as follows: C(max), 6.20 (0.75), 11.60 (1.95), and 25.34 (8.34) ng/mL, respectively; T(max), 5.70 (1.64), 6.00 (1.33), and 6.89 (1.41) h; AUC(0-t), 486.19 (80.00), 889.32 (239.49), and 1772.91 (784.07) ng x h/mL; AUC(0-infinity), 540.05 (89.68), 932.07 (230.82), and 1853.29 (776.85) ng x h/mL; t(1/2), 66.86 (11.75), 63.57 (12.58), and 62.06 (9.26) h; and MRT, 99.37 (16.96), 91.73 (18.16), and 89.56 (13.77) h. The main pharmacokinetic parameters found for memantine at doses of 5 mg once daily for 14 days were as follows: T(max), 6.80 (2.46) h; C(ssmax), 19.69 (2.00) ng/mL; C(ssmin), 12.76 (2.80) ng/mL; C(ssav), 16.10 (2.46) ng/mL; t(1/2), 64.57 (15.78) h; MRT, 93.17 (23.38) h; AUC(ss),386.37 (59.00) ng x h/mL; and DF, 44.47% (15.27%). One female subject withdrew from the study after a single 20-mg dose due to an AE (dizziness and vomiting); no other subjects experienced an AE. CONCLUSIONS: In these healthy Chinese subjects, the t(1/2) and MRT values were fixed and did not increase following the increased dose, and the AUC(infinity) and C(max) values increased following the increasing dosage of memantine. Linear pharmacokinetics was found at doses from 5 to 20 mg. The multiple-dose pharmacokinetic parameters (other than C(max)) were nearly similar compared with the single-dose administration. The maximum plasma concentration of memantine after multiple-dose administration was greater than that after a single-dose administration, suggesting memantine accumulation with multiple-dose administration of 5 mg and requiring further confirmation in larger studies.

Interaction of water-soluble cationic porphyrin with anionic surfactant.

The interaction of a cationic water-soluble porphyrin, 5,10,15,20-tetrakis [4-(3-pyridiniumpropoxy)phenyl]porphyrin tetrakisbromide (TPPOC3Py), with anionic surfactant, sodium dodecyl sulfate (SDS), in aqueous solution has been studied by means of UV-vis, (1)H NMR, fluorescence, circular dichroism (CD) spectra and dynamic laser light scattering (DLLS), and it reveals that TPPOC3Py forms porphyrin-surfactant complexes (aggregates), including ordered structures J- and H-aggregates, induced by association with surfactant monomers below the SDS critical micelle concentration (cmc), and forms micellized monomer upon the cmc, respectively. The position of TPPOC3Py in the micelle is determined, which is not in the micelle core instead of intercalated among the SDS chains, most likely with the pyridinium group extending into the polar headgroup region of the micelle.

Study on the inclusion behavior between meso-tetrakis[4-(3-pyridiniumpropoxy)phenyl]prophyrin tetrakisbromide and beta-cyclodextrin derivatives in aqueous solution.

The interaction of a cationic water-soluble porphyrin, 5,10,15,20-tetrakis[4-(3-pyridiniumpropoxy)phenyl]prophyrin tetrakisbromide (TPPOC3Py), with beta-CD and HP-beta-CD in aqueous solution has been studied by UV-vis, 1H NMR, 2D-NOESY and MALDI-TOF MS, and it reveals that a stable 1:1 inclusion complex between TPPOC3Py and HP-beta-CD or beta-CD has formed, in which one of the meso substituents of porphyrin ring has deeply penetrated through the cavity of HP-beta-CD from secondary face. The inclusion constants of the complexes of TPPOC3Py-beta-CD and TPPOC3Py-HP-beta-CD are (1.6+/-0.2)x10(3) M-1 and (8.9+/-0.4)x10(4) M-1, respectively.