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This paper aimed to develop a simple, sensitive, and rapid chromatographic procedure for the simultaneous analysis of human insulin and its main decomposition product using isocratic RP-HPLC/UV. A column type RP-C18 (100 × 4.6 mm, 3 μm particle size, and pore size 130 Å) was used.o-Nitrophenol was used as internal standard. The eluent consists of 62% KH2PO4buffer (0.1 M), 26% ACN, and 12% MeOH. The final pH was adjusted to 3.1. The eluent was pumped at a flow rate of 1.0 mL/min and the effluent was monitored using DAD detector at 214 nm. The method produces a linear response over the concentration range of 0.0106 to 0.6810 mg/mL with detection limit of 0.0029 mg/mL. Considering the specifications of this method, the system was found to be suitable for rapid, direct routine analysis and stability studies of insulin.

The aim of this work was to prepare and evaluate Tadalafil nanosuspensions and their PEG 4000 solid dispersion matrices to enhance its dissolution rate. Nanosuspensions were prepared by precipitation/ultrasonication technique at 5°C where different stabilizers were screened for stabilization. Nanosuspensions were characterized in terms of particle size and charge. Screening process limited suitable stabilizers into structurally related surfactants composed of a mixture of Tween80 and Span80 at 1:1 ratio (in percent, weight/volume) in adjusted alkaline pH (named TDTSp-OH). The surfactant mixture aided the production of nanosuspensions with an average particle size of 193 ± 8 nm and with short-term stability sufficient for further processing. Solid dispersion matrices made of dried Tadalafil nanosuspensions or dried Tadalafil raw powder suspensions and PEG 4000 as a carrier were prepared by direct compression. Drying was performed via dry heat or via freeze dry. Drug release studies showed that, in general, tablet formulations made of freeze-dried product exhibited faster initial release rates than the corresponding tablets made of oven-dried products which could be attributed to possible larger crystal growth and larger crushing strengths of oven-dried formulations. At best, 60% of drug was released from solid dispersion matrices, while more than 90% of drug was released from TDTSp-OH nanosuspension within the first 5 min. In conclusion, Tadalafil nanosuspensions obtained using a mixed surfactant system provided rapid dissolution rates of Tadalafil that can theoretically enhance its bioavailability.

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The aim of this study was to characterize a buccal mucoadhesive film using lidocaine and its hydrochloride salt (LDHCL) as a model drug. Buccal films were developed using carbopol 971P as a mucoadhesive polymer, and glycerol as a plasticizer. Scanning Electron Microscope, Differential Scanning Calorimetry, X-ray powder diffraction, and Fourier Transform Infra Red techniques were used to characterize the mucoadhesive films. Bioadhesive properties were evaluated using the Universal Instron Instrument with chicken pouch as a model tissue. LDHCL and its base were present in carbopol 971P films in a molecular dispersion state without exerting any effect on the glass transition of these films. The mucoadhesive force between the chicken pouches and the film containing glycerol did not change by time during the tested period (1-20 min), while increased with increasing the amount of glycerol (10-40% w/w of polymer content). Furthermore, a linear increase in the mucoadhesive force was accompanied by the increase in the film thickness, while a linear decrease followed by plateau was obtained when loading the patch with LDHCL at concentration above 1 mg/cm(2). Loading carbopol film with lidocaine base, in a concentration up to 6 mg/cm(2) decreased linearly the mucoadhesive properties, which could be attributed to salt formation between the acidic carboxylic moiety of carbopol and basic lidocaine.

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The copolymer of ammoniomethacrylate Eudragit RL (ERL) interacted with diclofenac acid salts (sodium and diethylamine salts) in aqueous solutions, forming a complex. Sorption experiments were done in aqueous solutions of either sodium lauryl sulfate (SLS), Tween 20, or Tween 80. The SLS competed strongly with the drug, even at low concentrations, and reduced significantly the amount of drug sorbed by ERL. Tweens at high concentrations exhibited two phase profiles: the sorption phase, which was short and during which drug concentration dropped sharply, and the release phase, during which the drug was released slowly over 24 hr and which was accompanied by dispersion of ERL particles into the colloidal dispersion. The interaction was dependent on temperature, ionic strength, and nature of the additives. The extent of interaction in water and phosphate buffer solutions was in the following order: water > pH 6 > pH 7-8. In-vitro dissolution studies of the dried complex were done over 24 hr. In water, the drug remained bound to the polymer. In aqueous surfactant solutions (SLS, Tween 20, and Tween 80) and phosphate buffer at pH 6.8, a linear relationship between drug concentration and the square root of time was obtained, indicating a matrix diffusion-controlled mechanism. However, 100% release was not reached, and resorption was observed in the phosphate buffer solution.