Development of Dipeptide -acetyl-L-cysteine Loaded Nanostructured Carriers Based on Inorganic Layered Hydroxides.

-acetyl-L-cysteine (NAC), a derivative of the L-cysteine amino acid, presents antioxidant and mucolytic properties of pharmaceutical interest. This work reports the preparation of organic-inorganic nanophases aiming for the development of drug delivery systems based on NAC intercalation into layered double hydroxides (LDH) of zinc-aluminum (ZnAl-NAC) and magnesium-aluminum (MgAl-NAC) compositions. A detailed characterization of the synthesized hybrid materials was performed, including X-ray diffraction (XRD) and pair distribution function (PDF) analysis, infrared and Raman spectroscopies, solid-state carbon and aluminum nuclear magnetic resonance (NMR), simultaneous thermogravimetric and differential scanning calorimetry coupled to mass spectrometry (TG/DSC-MS), scanning electron microscopy (SEM), and elemental chemical analysis to assess both chemical composition and structure of the samples.

In silico and in vitro prediction of gastrointestinal absorption from potential drug eremantholide C.

Objectives: Analysis of the biopharmaceutical properties of eremantholide C, sesquiterpene lactone with proven pharmacological activity and low toxicity, is required to evaluate its potential to become a drug.

Methods: Preliminary analysis of the physicochemical characteristics of eremantholide C was performed in silico. Equilibrium solubility was evaluated using the shake-flask method, at 37.

In Situ Intestinal Perfusion in Rodents: Future Perspectives for Application on Absorption Studies and Classification of Drugs.

Background: In 1995, the Biopharmaceutics Classification System (BCS) was proposed by Amidon and colleagues as a tool that considers two important parameters regarding drugs: solubility and permeability. Since then, several methods for solubility and permeability studies have been developed for drug delivery and absorption prediction. In recent years, permeability has gained a great highlight and the interaction between a molecule and a biological membrane is not enough to predict the in vivo behavior of a compound.

Single-Pass Intestinal Perfusion (SPIP) and prediction of fraction absorbed and permeability in humans: A study with antiretroviral drugs.

In recent years, the prediction of oral drug absorption in humans has been a challenge for researchers and many techniques for permeability studies have been developed for several purposes, including biowaiver processes. The Single-Pass Intestinal Perfusion (SPIP) method performed in rats can provide permeability results closest to in vivo condition. The purpose of the present study was to evaluate the intestinal permeability of the antiretroviral drugs lamivudine, stavudine and zidovudine using the SPIP method in rats and to predict their permeability (Peff,humans) and fraction absorbed (Fa) in humans.

Evaluating Potential P-gp Substrates: Main Aspects to Choose the Adequate Permeability Model for Assessing Gastrointestinal Drug Absorption.

The success of an oral drug route administration depends on many factors that interfere in its bioavailability, therapeutic efficacy and clinical safety. In human cells, ATP-dependent efflux transporter proteins, such as P-glycoprotein (P-gp), BCRP and MRP2, reduce the absorption of drugs. A tiered approach chosen to evaluate drugs as substrates or inhibitors of efflux pumps, particularly P-gp, should be carefully selected, since each study method has advantages and intrinsic limitations to their processes.

A critical review of properties of darunavir and analytical methods for its determination.

Darunavir is a synthetic non-peptidic protease inhibitor that has been shown to be extremely potent against wild-type HIV, and it is an important component of highly active antiretroviral treatment (HAART), which is considered as one of the most significant advances in the field of HIV therapy. However, there are some concerns about darunavir quality control. Darunavir shows pseudo-polymorphism: in different ambient conditions one pseudo-polymorphic form can change to another.

Pharmacokinetics and bioequivalence evaluation of cyclobenzaprine tablets.

The purpose of this study was to investigate cyclobenzaprine pharmacokinetics and to evaluate bioequivalence between two different tablet formulations containing the drug. An open, randomized, crossover, single-dose, two-period, and two-sequence design was employed. Tablets were administered to 23 healthy subjects after an overnight fasting and blood samples were collected up to 240 hours after drug administration.

Determination of lamivudine and zidovudine permeability using a different ex vivo method in Franz cells.

Introduction: The major processes that control the absorption of orally administered drugs are dissolution and gastrointestinal permeation. These processes depend on two main properties: solubility and permeability. Based on these characteristics, the Biopharmaceutical Classification System (BCS) was proposed as a tool to assist in biowaiver and bioavailability prediction of drugs.

Darunavir: a critical review of its properties, use and drug interactions.

Darunavir is a synthetic nonpeptidic protease inhibitor which has been shown to be extremely potent against wild-type HIV as well as a large panel of PI-resistant clinical isolates and shows a high genetic barrier to the development of antiretroviral resistance. The treatment of HIV/AIDS requires combinations of multiple antiretroviral drugs. In addition, patients frequently need to coadminister other medications for reasons including the prevention or treatment of opportunistic infections, treatment of concomitant illnesses and management of antiretroviral side effects.

Bioequivalence evaluation of single doses of two tramadol formulations: a randomized, open-label, two-period crossover study in healthy Brazilian volunteers.

Background: Tramadol is a well tolerated and effective analgesic used to treat moderate to severe pain. Several generic formulations of tramadol are available in Brazil; however, published information regarding their bioequivalence in the Brazilian population is not available. A study was designed for Brazilian regulatory authorities to allow marketing of a generic formulation.

Bioequivalence evaluation of two different tablet formulations of tinidazole in healthy volunteers.

The bioequivalence of two different tablet formulations of tinidazole (CAS 19387-91-8) was determined in healthy volunteers after a single dose in a randomized crossover study, with a 1-week washout period between the doses. Reference and test products were administered to 24 volunteers with 240 mL water after overnight fasting. Plasma concentrations of tinidazole were monitored by a high-performance liquid chromatographic method (HPLC) over a period of 72 h after the administration.

Bioequivalence assay between orally disintegrating and conventional tablet formulations in healthy volunteers.

The purpose of this study was to evaluate bioequivalence of two commercial 8 mg tablet formulations of ondansetrona available in the Brazilian market. In this study, a simple, rapid, sensitive and selective liquid chromatography-tandem mass spectrometry method is described for the determination of ondansetron in human plasma samples. The method was validated over a concentration range of 2.

Emulsified systems based on glyceryl monostearate and potassium cetyl phosphate: scale-up and characterization of physical properties.

Introducing a pharmaceutical product on the market involves several stages of research. The scale-up stage comprises the integration of previous phases of development and their integration. This phase is extremely important since many process limitations which do not appear on the small scale become significant on the transposition to a large one.

Bioequivalence and pharmacokinetics of two zidovudine formulations in healthy Brazilian volunteers: an open-label, randomized, single-dose, two-way crossover study.

Background: Zidovudine is a thymidine nucleoside reverse transcriptase inhibitor with activity against HIV type 1. Some (approximately 8) generic formulations of zidovudine are available in Brazil; however, based on a literature search, information concerning their bioavailability and pharmacokinetic properties in the Brazilian population has not been reported.

Objective: The aim of this study was to compare the bioavailability and pharmacokinetic properties of 2 capsule formulations of zidovudine 100 mg in healthy Brazilian volunteers.

Bioequivalence study of two oral formulations of cefadroxil in healthy volunteers.

Two different cefadroxil (CAS 50370-12-2) formulations were evaluated for their relative bioavailability in 24 healthy volunteers who received a single 500 mg oral dose of each preparation. An open, randomized clinical trial designed as a two-period crossover study with a 7-day washout period between doses was employed. Plasma samples for assessments of their cefadroxil concentration by HPLC-UV were obtained over 8 h after administration.

HPLC-UV determination of metformin in human plasma for application in pharmacokinetics and bioequivalence studies.

In this study, a simple, rapid and sensitive HPLC method with UV detection is described for determination of metformin in plasma samples from bioequivalence assays. Sample preparation was accomplished through protein precipitation with acetonitrile and chromatographic separation was performed on a reversed-phase phenyl column at 40 degrees C. Mobile phase consisted of a mixture of phosphate buffer and acetonitrile at flow rate of 1.

Bioavailability study of two oral formulations of didanosine in healthy volunteers.

An open-label, randomised, crossover single dose study, using 2 periods, 2 sequences, with a minimum washout period of 7 days, was conducted in order to assess the comparative bioavailability of two formulations of didanosine (CAS 69655-05-6) 100 mg tablets. Didanosine plasma concentrations were determined by means of a validated HPLC method [DAD detector, stavudine (CAS 3056-17-5) as an internal standard]. The limit of detection was 30 ng/ml.

Determination of lamivudine in human plasma by HPLC and its use in bioequivalence studies.

A simple, accurate, precise and sensitive high-performance liquid chromatographic (HPLC) method with ultraviolet detection was developed to quantificate lamivudine (3-TC) in human plasma samples from bioequivalence studies. 3-TC and stavudine (internal standard, I.S.