sodium-dodecyl-sulfate and acetylcellulose

A simple and inexpensive preconcentration technique has been developed for the ultra-trace determination of lead(II) using electrothermal atomic absorption spectrometry (ETAAS). The lead(II) complex with dicyclohexano-18-crown 6-ether (DC18C6) was extracted to a small piece of cellulose acetate-type membrane filter (2 × 5 mm) merely by vigorously eccentric stirring for 120 min under the coexistence of sodium dodecyl sulfate (SDS) at around pH 7. The extraction medium was inserted into a graphite cuvette for the determination of lead(II) by ETAAS. A linear relation was obtained for the range of 0.1-5.0 ng in 10 ml of lead(II) standard solution (r = 0.998). The detection limit was found to be 0.03 ng of lead(II) in 10 ml (0.003 µg l(-1)) of water sample. The proposed method was applied to the ultra-trace determination of lead(II) in river water, underground water, tap water, and snow fall samples.

Topics: Cellulose; Crown Ethers; Filtration; Lead; Membranes, Artificial; Rivers; Snow; Sodium Dodecyl Sulfate; Solid Phase Extraction; Spectrophotometry, Atomic; Water; Water Pollutants, Chemical

Colon targeted delivery systems of metronidazole (MTZ) based on osmotic technology were developed. The developed systems consisted of osmotic core (drug, osmotic agent and wicking agent), coated with semipermeable membrane (SPM) containing guar gum as pore former, coated core were then further coated with enteric coating to protect the system from acidic environment of stomach. The effect of various formulation variables namely the level of wicking agent (sodium lauryl sulphate), osmotic agent in the osmotic core, the level of pore former (guar gum) in SPM, and the thickness of SPM, were studied on physical parameters and drug release characteristics of developed formulations. MTZ release was inversely proportional to SPM thickness, but directly related to the level of pore former, wicking agent and osmotic agent. On the other hand burst strength of the exhausted shells was decreased with the increase in level of pore former in the membrane but increased with the increase in the thickness of SPM. The drug release from the developed formulations was independent of pH, and agitation intensity, but dependent on the osmotic pressure of the release media. The thickness of enteric coating could prevent formation of delivery pores before contact with simulated colonic fluid, but had no effect on drug release. Result of SEM studies showed the formation of in-situ delivery pores in the membrane from where the drug release occurred, and the number of pores formed were directly related to the initial level of pore former (guar gum) in SPM. The manufacturing procedure was found to be reproducible and formulations were found to be stable during 3 months of accelerated stability studies.

Topics: Antiprotozoal Agents; Bacteria; Cellulose; Chemistry, Pharmaceutical; Colon; Drug Delivery Systems; Excipients; Galactans; Humans; Intestine, Small; Mannans; Membranes, Artificial; Metronidazole; Microscopy, Electron, Scanning; Osmosis; Plant Gums; Reproducibility of Results; Sodium Dodecyl Sulfate

Oral osmotic devices including an elementary osmotic pump (EOP) are efficient systems for the delivery of drugs with high/moderately water-solubility. In this study we designed a new type of EOP for the efficient delivery of poorly water-soluble and practically insoluble drugs. In this system, called swellable elementary osmotic pump (SEOP), drug is released from the delivery orifice in the form of a very fine dispersion of drug in gel which is ready for dissolution and absorption. Factors affecting the release of drug from the SEOP containing a poorly water-soluble drug, nifedipine, were explored extensively. To this end, effect of swelling and wetting agents, orifice size, concentration of osmotic agent, and hydrophobic plasticizer were investigated. Interestingly, in the absence or low concentration of a hydrophobic plasticizer (caster oil), the osmotic devices did not retain their integrity in dissolution media. Caster oil in concentration of > 1% was necessary for tablets to retain their integrity during dissolution process. A zero-order release kinetics for nifedipine was achieved following the effective optimization of the concentrations of swelling agent, osmotic agent, wetting agent, and also size of orifice and membrane thickness in SEOP. The zero-order release lasted for 10 hr at pH 6.8 dissolution medium. The designed SEOP is suggested as an efficient controlled delivery system for oral delivery of a poorly water soluble drug such as nifedipine.

Topics: Administration, Oral; Castor Oil; Cellulose; Chemistry, Pharmaceutical; Delayed-Action Preparations; Drug Carriers; Drug Compounding; Gels; Hydrogen-Ion Concentration; Hypromellose Derivatives; Kinetics; Membranes, Artificial; Methylcellulose; Models, Chemical; Nifedipine; Osmosis; Permeability; Plasticizers; Potassium Chloride; Sodium Dodecyl Sulfate; Solubility; Tablets; Water; Wetting Agents

An asymmetric membrane capsule of cellulose acetate for osmotic delivery of flurbiprofen has been developed and influence of osmogents and solubilizing agent on in vitro drug release were evaluated. The capsule membrane was prepared by the phase inversion technique. To ensure the osmotic delivery of drug, two approaches were adopted: (i) the drug was encapsulated with osmogents like sodium chloride and mannitol to increase the osmotic pressure of the core, and (ii) the drug was encapsulated with sodium lauryl sulfate in the core of the formulation to increase the solubility and thus its osmotic pressure. Scanning electron microscopy of the membrane confirmed its porous, dense asymmetric nature. Dye test revealed in situ pore formation. The in vitro release study showed that as the proportion of osmogent and solubilizing agent was increased the release rate also increased. A good correlation was observed between the zero-order rate constant and the amount of the osmogent and solubilizing agent used.

Topics: Amaranth Dye; Analysis of Variance; Anti-Inflammatory Agents, Non-Steroidal; Capsules; Cellulose; Diffusion; Drug Delivery Systems; Flurbiprofen; Mannitol; Microscopy, Electron, Scanning; Osmolar Concentration; Osmosis; Osmotic Pressure; Porosity; Sodium Chloride; Sodium Dodecyl Sulfate; Solubility; Technology, Pharmaceutical

The possibility of electrochemical modification of cellulose acetate membrane upon immobilization of the anionic surfactant (SDS) has been explored on the basis of membrane potential studies. Surface tension measurements with and without cellulose acetate membrane were carried out to ascertain the extent of immobilization of the surfactant. Cellulose acetate membrane practically does not exhibit any ion selectivity. However, modified membrane exhibits cation selectivity which varies with concentration of the surfactant till its critical micelle concentration is reached. An attempt has also been made to demonstrate correspondence between the immobilized surfactant and the permselectivity of the membrane.

Topics: Cellulose; Electrochemistry; Membrane Potentials; Membranes, Artificial; Sodium Dodecyl Sulfate; Surface Properties; Surface Tension; Surface-Active Agents