Antibiotic solutions

Deluca, P. P. Phase transitions in frozen antibiotic solutions, p. 87 bis 92, International Institute of Refrigeration (Comm. Cl, Tokyo, 1985)... 

For the experiment, the dorsal skin of young rats (Wistar or a comparable strain) is shaved and washed with an antibiotic solution (containing, e.g., streptomycin, penicillin, chloramphenicol, and amphotericin in concentrations inhibiting bacterial growth). After skin excision, excess fat is peeled off and the skin is placed over the end of a polytetrafluoroethylene tube with the epidermal side in touch with the hollow cylinder. The skin is fixed with an O-ring and the tube interior is sealed. The side of the dermis is then submersed in a magnesium sulphate solution (154 mM). The samples are applied at 30°C to the epidermal side of the skin in such a way that the skin interface is fully covered. After the incubation time, the substances are removed with prewarmed water the skin surface tension is decreased with ethanol which is subsequently replaced with magnesium sulphate solution (154 mM). 

Only solutions of lipophilic antibiotics are able to cross the external barrier of the cornea (drops) and the internal blood-retina barrier (systemic administration) to yield sufficient concentrations in the internal eye (vitreous). Keratitis and ulceration of the cornea can be treated by frequent administration of highly concentrated (fortified) antibiotic drops. In endophtalmitis, emergency vitreous aspirate and in-travitreal and subconjunctival injection of antibiotic solutions with a long half-life is the cornerstone of treatment. These solutions should be prepared by the hospital pharmacy. Empiric topical treatment of minor external eye infections consists of antibiotic containing gels or ointments. 

Antibiotic solution X100 - available from most suppliers... 

Application of solutions or ointments directly to the lid margin is especially helpful in treating seborrheic or infectious blepharitis. After several drops of the antibiotic solution or detergent, such as baby shampoo, are placed on the end of a cotton-tipped appUcator, the solution is applied to the Ud margin with the eyeUds either opened or closed (Figure 3-11). Antibiotic ointments are applied in the same way. 

The application of hot compresses several times daily serves to hasten pointing and drainage. Generally, this is all that is necessary for resolution.Topical application of antibiotic solutions or ointments may prevent infection of surroimding lash follicles but does not affect the course of the external hordeolum itself. One of the best methods to hasten drainage is to epilate the involved lash, which creates an effective drainage channel. 

L. Gatlin and P. Deluca, A study of the phase separation in frozen antibiotic solutions by differential scanning calorimetry. J. Parent. Drug Assoc. 34 398—408 (1980). 

Warming may have a beneficial effect. For instance, the temperature of fluids atomized in air-jet nebulizers decreases by approximately 10-15°C during use, resulting in bronchoconstriction in some asthma suffers.Bronchoconstriction, which is most marked at 5°C, disappears at 37°C and thus may be minimized by using an ultrasonic device. Furthermore, when solutions of drugs with low solubility are to be nebulized, ultrasonic nebulizers, which warm the solutions, may be preferable to air-jet devices, which cool them and may cause precipitation. However, the heat generated may harm heat-labile materials such as diethylenetriaminepentoacetic acid ( mTc-/DTPA), " proteins, and some antibiotic solutions. Thus, ultrasonic nebulizers are specifically prohibited for aero-solization of recombinant human deoxyribonuclease (rhDNase). ... 

High-concentration, "fortified" antibiotic solutions are made up from aqueous formulations for parenteral administration in BSS or artificial tears. These may be instilled directly onto the ocular surface or added to a commercial formulation to reach the required final concentration. The recommended concentrations of fortified antibiotic solutions for topical use are shown in Table 13.1. 

Gatlin, L. and P. Deluca (1980). Study of phase transitions in frozen antibiotic solutions by DSC. J. Parenteral Drug Assoc. 34, 398-408. 

Figure 11.3 shows the solubilities (defined as total solute dissolved) of some /3-lactam antibiotics as a function of pH. All of these compounds exhibit a minimum in their solubility, C o, at the isoelectric point of the compound. At a pH significantly removed from the isoelectric point, the total (apparent) solubility is increased. The U-shape of the apparent solubility versus pH curve can be described by taking into account the acid-base equilibria of the antibiotic solute and assuming that the solute in the crystal is in the zwitterionic (isoelectric) form. 

Instruct the client to clean the eye with antibiotic solution prior to applying ointment. 

The eye should be cleaned with warm water prior to applying antibiotic ointment. There is no antibiotic solution used prior to using ophthalmic ointment. 

The predominant method of sterilization for BPCs is by membrane filtration. This filtration will require validation in accord with regulatory expectations. Adaptations to the common filter validation methodologies may be required for certain solvents and/or antibiotic solutions. Subsequent to the filtration step, the succeeding unit operations must be carried out using facilities, equipment, and methods designed to prevent the ingress of microorganisms. The remainder of this section reviews considerations relative to sterile BPC preparation under these constraints. 

Wong, J. S., Rein, A. J., Wilks, D. Wilks, P. (1984) Infrared spectroscopy of aqueous antibiotics solutions. Applied spectroscopy 38, 32-35. 

Antibiotic solutions placed in reservoirs need sterilising. Autoclaving can only be used for a small number of antibiotics, and many need to be sterilised by membrane filtration. The use of cups to hold the antibiotic has the advantage that non-sterile solutions may be used. 

In developing a countertop spray cleaner effective against Salmonella bacteria, candidate antibiotics are tested on agarose plates inoculated with Salmonella bacteria. Single drops (0.1 mL) of 1M antibiotic solutions are introduced to each plate, and the zones of Salmonella inhibition are measured after a standard incubation time. The standard for the experiment is a 70% solution of ethanol in water. Diameters (in cm) for each of 16 replications for each antibiotic are given below. Which antibiotic do you recommend ... 

It is found that minimally inhibitoiy concentration of liposomal antibiotic solution with the neutral charge (lecithin liposomes) decreased in three times in comparison with minimally inhibitory concentration of the lincomycin solution concerning Staphylococcus aureus. 

The cytotoxicity assay is usually performed by determining the viability of suitable cell lines in the presence of polymers. For this test, 3-5 mm discs of polymer film are cut and sterilised under standard conditions (at 121 C and 6.8 kg (15 lb) pressure for 15 min). The cell growth in the presence of the polymer films is measured under a controlled atmosphere (CO2 incubator, 37"C) using an appropriate culture medium, supplemented by 10% fetal bovine serum and penicillin-streptomycin antibiotic solution. Confluent monolayers are propagated by trypsinisation (0.25% trypsin and 0.02% EDTA, ethylene diamine tetraacetic acid) and re-plated at 2 x 10 cells/mL in a sterile polystyrene cell culture plate, then incubated for 24,48 and 72 h. The morphology of the cells is analysed by light naicroscopy (Leica) after... 

In 2005 Blanchemain et al. immersed PET vascular prostheses into a solution containing a polycarboxylic acid, a cyclodextrin (CD) (Fig. 13.17) and a catalyst, and placed them into a thermofixation oven before impregnation with an antibiotic solution (vancomycin). They demonstrate the feasibility of coating CDs onto vascular Dacron grafts and there was no toxicity with the different cyclodextrins. A linear release of antibiotics was depicted over 50 days, demonstrating also that cyclodextrin grafting was an efficient dmg delivery system [49]. 

ChT films were obtained by means of casting of the polymer solution in 1% acetic acid onto the glass surface with the formation of chitosan acetate (ChTA). Aqueous antibiotic solution was added to the ChT solution immediately before films formation. The content of the medicinal preparation in the films was 0.01,0.05 and 0.1 mol/mol ChT. The film thickness in all experiments was maintained constant and equal 100 microns. To study the release kinetics of MS the sample was placed in a cell with distilled water. Stand out in the aqueous phase AM recorded spectropho-tometrically at a wavelength of 267 nm, corresponding to the maximum absorption in the UV spectrum of MS. Quantity of AM released from the film at time t (G ) was estimated from the calibration curve. The establishment of a constant concentration in the solution of MS is the time to equilibrium. MS mass fiaction a, available for diffusion, assessed as the quantity of films released from the antibiotic to its total amount entered in the film. 

Fig. 1. Cephamycin A diffusion plate assay. This assay was performed versus P. vulgaris MB-838 in nutrient agar plus 0.2% yeast extract with 7-mm filter paper disks soaked in antibiotic solutions. Data from Stapley et al., 1972.

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