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PubMedDate not supplied

Microemulsions as potential ocular drug delivery systems: phase diagrams and physical properties depending on ingredients.

The microemulsion systems, both o/w and w/o, composed of isopropyl myristate, soybean lecithin (Epikuron 200), Polysorbate 80, Cremophor EL, n-butanol and triacetine, taken at various amounts and in various combinations, were tested in order to assess their physical-chemical properties. Some ingredients of the microemulsions were physiologically acceptable, except one formulation containing n-butanol used as a model reference system. Phase diagrams were made for all microemulsions studied in order to test the influence of components on the boundaries of the stable microemulsion domains. The greatest area of stable microemulsion system was obtained for the formulation in which n-butanol was used, while the smallest area was obtained when soybean lecithin (Epikuron 200) was used as a surfactant. The following physical parameters were analyzed: osmotic tension, density, viscosity, refractive index. pH and particle size. Microemulsions stored at 25 degrees C for the period up to 12 months, showed physical changes depending on ingredients. The study made it possible to select the most stable microemulsion system meeting the requirements of eye drops.

Drug Carriers↗
PubMed1991

Assessment of triethanolamine salicylate release from the dermatological bases and the commercial products.

Recently, triethanolamine salicylate (TEAS) is frequently being incorporated in several over-the-counter topical analgesic pharmaceutical products. Since the clinical efficacy of such dosage form depends upon the release of the active ingredient at the site of application, the present study was undertaken to study the in vitro release of the (TEAS) from commonly used ointment bases and two most popular commercial products in the U.S. market. Also, the effects of various penetration enhancers, such as, ethanol, propylene glycol, polyethylene glycol-400, dimethyl-sulfoxide (DMSO), polysorbate-80 and urea were evaluated. In general, the drug release from the experimental formulations was higher than the commercial products studied. The inclusion of the penetration enhancing ingredients increased the drug release from some of the formulations evaluated. The hydrophilic emulsion base with 10% ethanol exhibited the best in vitro drug release. The apparent viscosity profiles of the formulations showed no definite relationship with the amounts of drug release. However, significant differences in the (TEAS) release from the experimental formulations were observed.

Administration, Topical↗
PubMed1991

[Formulation and analysis of suppositories containing papaverine hydrochloride. Part 2. In vitro membrane diffusion studies].

Rectal suppositories with 0.10 g/2.0 g Papaverine hydrochloride content were made with 12 different vehicles. The membrane diffusion method was used to study the factors influencing the in vitro drug liberation. The Polysorbate 20 and 61 tenside pair, the optimal concentration of which was 5% each, was found to influence diffusion favourably. Neutral oils softening the consistency (Miglyol 812 and Estasan), similarly in 5%, also had a favourable effect on the in vitro diffusion by increasing the spreading properties. As to the lipophil suppository masses with high and low hydroxyl numbers, only the latter could be used favourably. The 6-month-long storage resulted in drug retention in several experimental series. Correlation was found in several cases between the physical parameters of the suppositories and their in vitro drug liberation. Finally, with the help of linear regression calculation and in view of the in vitro relative bioavailability values the optimal vehicle is suggested for the formulation of suppositories containing Papaverine hydrochloride. The triglyceride type Estaram 299 was found to be the most suitable in every respect, either in itself or combined with 5% neutral oil.

Diffusion↗
PubMed1991

[The effect of endogenous factors and physical loading on the formation of moisture excretion and detoxication by the lungs].

Overall 101 students (a control group), 68 persons from an ambulatory group with exogenous factors at risk for pulmonary diseases, and 122 patients with exacerbation of nonspecific pulmonary diseases were examined for the volume of exhaled air condensate, the content in it of medium-weight molecules and protein by means of two methods (according to Lowry and by adsorption using polysorb). The students were found to have the worst parameters. Exacerbation of the disease led to their increase. Exercise blocked transport of water, protein and medium-weight molecules to the condensate, whose intensity depended on the age, sex and body mass. This stresses the importance of exogenous factors in the maintenance of moisture excretion and detoxication by the lungs. It is recommended that the new methodological approach to assessing the response to exercise according to moisture excretion function of the lungs may be applied.

Adult↗
PubMed1991

Biophysical absorption models for phenyl-alkyl acids in the absence and in the presence of surfactants. Studies in the rat small intestine.

The present study reviews and checks, by means of experimental work, some theoretical principles of a novel absorption-lipophilicity approach (Pl [symbol: see text] 160-Delfina et al., 1987), used to interpret the effects of synthetic surfactants on drug absorption. For this purpose the correlations between intestinal rat gut absorption constants and lipophilicity indexes are analyzed for a group of compounds belonging to a true homologous series (w-phenyl-alkyl carboxylic acids), in the absence and in the presence of polysorbate 80 in the luminal fluid. Evidence is given for the following surfactant actions: (a) at critical micelle concentration (CMC), the surfactant increases membrane polarity and simultaneously nullifies the limiting character of the stagnant aqueous layer adjacent to the membrane; (b) at supramicellar concentrations (SMC) the above actions become almost completely masked by the micellar solubilization of the compounds, which decreases their absorption rate constants. As a consequence of these interactions, correlation between membrane absorption and lipophilicity, which was clearly hyperbolic in free solution, becomes potential in the presence of surfactant at CMC, whereas at SMC a bilinear correlation is found. Pore absorption was much less affected. Mathematical and physiochemical reasons for this behaviour are outlined, and practical implications are briefly discussed.

Animals↗
PubMed1976

The effect of some additives on the adsorption of tetracycline hydrochloride on magnesium trisilicate and milk.

The effect of various additives on the adsorption of tetracycline hydrochloride on magnesium trisilicate or milk was investigated. Adsorption-elution, dialysis and sedimentation volume measurements were used in the present investigation. Citric acid was found to exert the highest adsorption suppressing effect of the antibiotic on both antacids. The nonionic surfactants, polyoxyethylene-23-lauryl ether (Brij 35) and polysorbate 80, had an intermediate action, while polyethylene glycol 6000 (PEG-6000), polyvinylpyrrolidone (PVP), sodium carboxymethylcellulose (CMC) and urea had only a slight effect. On the other hand, the effect of sodium benzoate and sodium salicylate varied with concentration. Results of the elution study showed that the efficiency of the additives, as eluting agents, was more or less parallel with their influence on adsorption. The presence of citrate or Brij 35, having the highest adsorption-suppressing effect, was found to have a negligible effect on the chemical stability or microbiological activity of tetracycline. Conclusions were made that the incorporation of some of these additives may possibly reduce tetracycline-antacids interactions and consequently improve the antibiotic availability when co-administered with antacids.

Adjuvants, Pharmaceutic↗
PubMed1991

[Principles of complex treatment of infection in emergency surgery].

The analysis of 140 cases of acute surgical sepsis is presented. The general principles for the treatment of sepsis in emergency surgery were established. The most effective are the guided laparotomy in peritoneal sepsis, use of intravascular laser blood irradiation, chemotherapeutical means and dressing materials (polysorb, carboserix, collocyl etc.), different gaseous media (aeroionotherapy, oxygenation, ozonized guided antibacterial medium) which have favourable effect on the reparative processes in the primary foci of infection. Resulting from the use of complex treatment, the decrease in lethality from 75 to 35.7% was noted.

Adolescent↗
PubMedDate not supplied

The use of surface tension measurements in the design of antibody-based product formulations.

Many proteins in aqueous solution are susceptible to interfacial denaturation and precipitation during mechanical agitation. With the large number of protein parenteral products currently in research or clinical testing, it is important not only to understand this denaturation process but also to develop effective methods for stabilizing the products. Surfactants, such as Polysorbate 80 or sodium dodecyl sulfate (SDS), are frequently used to stabilize parenteral products. While it is a commonly accepted technique, little has been published about the precipitation and stabilization processes in general. We describe the stabilization of antibody products in solution by preferential adsorption of a water-soluble, non-ionic surfactant at the air-liquid interface. Data are presented from antibody and immunotoxin solution shake studies and surface tension measurements to support the utility of surface tension measurements in formulation design.

Adsorption↗
PubMed1976

Prostaglandins, nonsteroidal anti-inflammatory agents and eye disease.

The prostaglandins produce elevation of intraocular pressure and breakdown of the blood-aqueous barrier. They act via the secondary messenger system, cyclic AMP. Although the pathogenesis of many forms of ocular inflammation, both external and internal, is unclear, it is evident that some forms of ocular inflammation are prostaglandin-mediated, at least in part. Others may be totally mediated by prostaglandin synthesis. At present the corticosteroids are the mainstay of therapy of these conditions. However, the corticosteroids are poor inhibitors of prostaglandin synthesis and have many deleterious side effects such as induction of ocular hypertension, cataract, and infection. The search for new agents that will obviate these side effects and be more specific for the disease process is crucial. The discovery that the mode of action of many nonsteroidal anti-inflammatory agents is via inhibition of prostaglandin synthesis places a premium on elucidating which of these agents is most effective and least toxic in the eye and by which route of administration. The arachidonic acid screening model is ideal for initially choosing which agent has the greatest potential clinically. Arachidonic acid, a PGE2 precursor, when given topically also elevates intraocular pressure and aqueous humor protein, and these effects are blocked by the nonsteroidal anti-inflammatory drugs. This occurs if the arachidonic acid is injected into the vitreous humor, too, providing evidence that this in vivo model involves intraocular mechanisms. Utilizing the arachidonic acid system, a comparative study of nonsteroidal inhibitors of prostaglandin synthesis shows that the most effective of 14 agents were flurbiprofen solution and suspensions of polysorbate-dispersed indoxole, meclofenamic acid, indomethacin, and clonixin. Animal uveitis is not an ideal model for the human condition. Nevertheless, proving the superior efficacy of a screened drug in this system will identify those drugs to be tested in the human disease states. Only after the very few best drugs of this nature are identified should the ultimate steps of human testing be initiated.

Animals↗
PubMed1990

The relation of clinical catastrophes, endogenous oxalate production, and urolithiasis.

A dose-related toxicity syndrome of renal, cerebral, and liver dysfunction; metabolic acidosis; and deposition of calcium oxalate crystals in tissues is reported in association with various apparently unrelated treatments for a wide range of diseases. The parenteral nutrient xylitol, the hyperosmolar agent glycerol, the polysorbate emulsifiers (e.g., in vitamin E preparations), the anesthetic methoxyflurane, and possibly the experimental hypoglycemic agent dichloroacetate all produce a toxicity syndrome very similar to that of ethylene glycol poisoning. In long-term, high-dose oral toxicity studies with rodents, these or similar agents also produce calcium oxalate bladder stones and bladder tumors. Studies with both unlabeled and labeled agents in humans and animals and in vitro experiments with purified enzymes, tissue homogenates, and isolated hepatocytes have provided both strong circumstantial and direct evidence for the existence of minor pathways of carbohydrate metabolism and of oxidative dealkylation and dehalogenation reactions in drug biotransformations that link these agents to endogenous oxalate production. Because urinary oxalate is now considered to be a critical factor in stone formation and because it is increasingly accepted that 80-90% of urinary oxalate is produced endogenously, it is now possible to formulate pathways that link oxalate production with dietary macronutrients. Therapeutic modifications of diet, in vivo hormonal milieu, and intracellular metabolic controls in relation to endogenous oxalate production may provide new forms of treatment for urolithiasis.

Animals↗
PubMed1989

Influence of drug loading on coated beads release using air suspension technique.

Spherical granules were prepared by loading a drug such as Indobufen on 40-45 mesh non-pareil seeds using air suspension coating technique (Wurster process, Uniglatt). The drug was added by spraying a formulated aqueous dispersion onto inert granules in different amounts employing two drug particle sizes with different surface areas. Then all active beads were coated with different thicknesses of polymeric film using the same fluid bed employed for loading the drug. The coatings were applied from aqueous dispersions (pseudolatex) of ethyl cellulose (Aquacoat ECD-30). In this system the drug diffusion is governed by the intrinsic pore network of the membrane. The finest drug particle size gave the fastest drug release rates. Moreover, the lowest drug loadings on inert granules resulted in the slowest drug release. Nevertheless thicker film coats involved a delay of drug release. Further preparations were made to evaluate the influence of changing the seed size to 25-30 mesh, loading the same amount of the drug and obtaining the increased surface are of the individual bead. In order to improve the drug release profile, the effect of changing diethylphthalate to the more water-soluble triethylcitrate and the addition of hydroxypropylmethyl cellulose or polysorbate 80 were also evaluated. In this case the drug diffusion is controlled by dissolution of a part of membrane leaving small channels of polymer coating.

Chemical Phenomena↗
PubMed1986

Absorption, distribution and metabolism of clioquinol in clioquinol-sensitive and -resistant neonatal rats.

Three types of rats with respect to sensitivity to clioquinol have been identified, the highly sensitive (S-rat), the intermediately sensitive, and the resistant (R-rat). In a toxicity test that lasted for 20 d after birth, the difference in sensitivity to clioquinol between S- and R-rats was confirmed by repeated subcutaneous administration of a clioquinol suspension prepared with polysorbate 80 (clioquinol dose of 150 or 300 mg/kg/d). Plasma and tissue concentrations of clioquinol and the rate of metabolism of the drug in neonatal S- and R-rats were measured. Plasma concentration of clioquinol in 1-d-old S-rats after a single subcutaneous administration was higher than that in the same age R-rats and the area under the mean plasma concentration-time curve for the S-rats was approximately twice that for the R-rats. In addition, clioquinol concentrations in liver, kidney and brain of S-rats at 9 h after the administration were more than twice those of the R-rats. From the experiments on the formation of clioquinol glucuronide and sulfate with 9000 g supernatant fraction of liver, it was suggested that the difference in the plasma concentration after the administration may be responsible for the difference in the metabolizing rate of clioquinol.

Animals↗
PubMedDate not supplied

The effects of anticalcification treatments on bioprosthetic heart valves implanted in sheep.

Several preimplantation processes have been shown to inhibit the calcification of pieces of porcine aortic valves and of bovine parietal pericardium implanted subcutaneously in rats. To investigate the effectiveness of these processes in modifying the calcification of bioprosthetic valves implanted in an intracardiac position, mitral and tricuspid valve replacements were performed in young sheep. Bioprosthetic valves treated with the following preimplantation processes were studied: 1) surfactants, including sodium dodecyl sulfate, polysorbate-80, Triton X-100 and N-lauryl sarcosine; 2) covalently bound aminohydroxypropane diphosphonic acid; 3) toluidine blue; and 4) incorporation of polyacrylamide into valvular tissues. Quantitative calcium analyses showed that only the surfactants substantially reduced calcification of bioprostheses implanted in intracardiac positions. This effect was evident only in porcine aortic valvular bioprostheses, and not in pericardial bioprostheses. Triton X-100 and N-lauryl sarcosine not only reduced calcification but also induced alterations that decreased the durability of the valves. Toluidine blue decreased calcification to a degree that was statistically significant but not biologically important, while polyacrylamide incorporation and diphosphonate binding increased calcification. Thus, data regarding anticalcification treatments obtained from subcutaneous implantation studies in small animal models should be interpreted cautiously and validated by studies with intracardiac valvular implantation in large animals.

Animals↗
PubMed1988

The effects of a mixture of surface-active agents (Sonarex) on upper airways resistance and snoring in anaesthetized dogs.

We measured upper airways resistance from the trachea and from the pharynx to the atmosphere, EMG of the genioglossus muscle and the sound of snoring, in anaesthetized greyhounds, breathing spontaneously through the upper airways. Using extra-corporeally produced continuous flow we determined flow/pressure curves for the upper airways and resistances from the trachea and from the pharynx. We tested the effects of 0.9% saline and of Sonarex (a proprietary mixture containing sodium chloride, glycerol, polysorbate 80 and benzalkonium chloride). Both saline and Sonarex decreased upper airways resistance, but the latter did so more consistently. With Sonarex, genioglossus activity increased and the sound of snoring decreased. Flow/pressure curves 5-20 min after Sonarex showed a decrease in upper airways resistance and a smoother curve, whereas those with saline showed an increase in resistance. The sound produced by continuous flow through the upper airways was decreased by Sonarex but increased by saline. Thus, both Sonarex and saline decrease upper airways resistance, but Sonarex also reduces the sound of snoring and the resistance and sound of continuous airflow through the upper airways.

Airway Resistance↗
PubMed1986

The calibration, control and use of a diluted bovine tuberculin (PPD) for testing cattle in areas free from tuberculosis.

In order to reduce the number of the so-called non-specific reactors of cattle in areas attested to be free from tuberculosis a 500 IU dilution of polysorbate-stabilized bovine PPD has been produced since 1971. This dilution is the result of field trials in such an area. The preparation is standardized according to the Requirements for Tuberculins. The stability of each batch is controlled in comparison with a lyophilized reference preparation during the whole time of its use. The use of this diluted tuberculin was regulated by instructions of our national veterinary authority in 1971 and 1975 as follows: Use only for testing cattle in areas where all herds have been attested free from tuberculosis for 2 years or more, not to be used on cattle for sale or in comparative tests. Maximal interval between tuberculin treatment 1 year. Notice of each reaction. Documentation according to the regulations of veterinary law of the GDR. Depending on the kind and level of mycobacterial sensitization in a definite area and on the mode of keeping cattle, the number of cross reactors has been reduced as a rule to 1/3 by the use of the diluted bovine PPD in comparison with the normal mammalian PPD "Dessau".

Animals↗
PubMed1986

Povidone-iodine in polyethylene oxide hydrogel dressing. Effect on multiplication of Staphylococcus aureus in partial-thickness wounds.

We studied the ability of a polyethylene oxide hydrogel dressing (Vigilon) containing povidone-iodine to prevent Staphylococcus aureus proliferation in partial-thickness wounds. We previously reported that a single application of povidone-iodine on wounds challenged with 2 X 10(6) S aureus was not effective in reducing the number of S aureus after 24 hours. It was therefore hypothesized that povidone-iodine might be effective if it was available continuously and applied to wounds containing a smaller number of bacteria. To test this hypothesis, we made multiple partial-thickness wounds (5 X 7 X 0.3 mm) on six domestic pigs. We then inoculated the wounds by scrubbing them with either a low concentration (log 3.5) or a high concentration (log 7) of S aureus suspension. The wounds were either treated with Vigilon or Vigilon containing povidone-iodine or left air exposed. Wounds from each of these treatment groups were cultured by the scrub technique for S aureus with a 0.5% sodium thiosulfate-polysorbate (Tween) 80 solution 5 minutes, 30 minutes, 24 hours, or 48 hours later. A significant reduction in the number of S aureus recovered from wounds treated with Vigilon containing povidone-iodine was seen with the group inoculated with a low bacterial concentration after 24 hours; but no reductions were observed when wounds were inoculated with the higher bacterial concentration of log 7. We found Vigilon containing povidone-iodine to be an effective inhibitor of S aureus in wounds over a 24-hour period when the organism was present in low numbers.

Animals↗
PubMed1985

Pharmacokinetics and metabolism of ryodipine in rats.

2,6-Dimethyl-3,5-dimethoxycarbonyl-4-(o-difluoromethoxyphenyl)-1, 4-dihydropyridine (ryodipine, PP-1466) at oral administration in the form of a suspension with Tween (polysorbate) 80 addition is comparatively rapidly absorbed in the gastro-intestinal tract and circulates in blood for a long period of time. PP-1466 practically does not bind to plasma proteins. The drug is mainly excreted via the kidneys and with faeces by 49 and 46% of the dose administered after 96 h, respectively. PP-1466 metabolites are present in rat urine-2,6-dimethyl-4-arylpyridine-3,5-dicarbonic acid derivatives: oxidation product of PP-1466 dihydropyridine cycle into pyridine one, products of partial or complete hydrolysis of ester groups of PP-1466 oxidized form, lactones. There have been performed the synthesis of labelled 14C-PP-1466 as well as counter-synthesis of PP-1466 metabolites. Unchanged PP-1466 is not detected in urine.

Animals↗