Availability preparation

Table 6.7 shows the available preparative columns and corresponding analytical columns. Preparative columns are also available in larger diameters of up to 50 mm. 

Kane JS (1992) Reference samples for use in analytical geochemistry their availability, preparation, and appropriate use. Joum Geochem Explor 44 37-63. 

The fraction of drug absorbed, F, represents the ratio of AUC of drug from a dosage form to the AUC of the same drug from a readily available preparation such as an intravenous injection where the drug is administered directly in the blood stream. This may be expressed as follows ... 

To help differentiate between commercially available preparations. 

The production of optically active cyanohydrins, with nitrile and alcohol functional groups that can each be readily derivatized, is an increasingly significant organic synthesis method. Hydroxynitrile lyase (HNL) enzymes have been shown to be very effective biocatalysts for the formation of these compounds from a variety of aldehyde and aliphatic ketone starting materials.Recent work has also expanded the application of HNLs to the asymmetric production of cyanohydrins from aromatic ketones. In particular, commercially available preparations of these enzymes have been utilized for high ee (5)-cyanohydrin synthesis from phenylacetones with a variety of different aromatic substitutions (Figure 8.1). 

Two cautious, but hopeful, reviews [362,362a] concluded, from evidence then to hand that the currently available preparation of disodium cromoglycate with isoprenaline could benefit patients with allergic asthma, but both expressed the hope that results from cromoglycic acid without isoprenaline would soon clarify the position. 

Initial attempts to prepare Cf metal using metallothermic reduction methods (Section II,A) were less than successful due to the high vapor pressure of Cf metal 28, 46). Reduction of californium oxide with La metal (Section II,B) and collection of the product Cf metal on a fused silica fiber (in the apparatus shown schematically in Fig. 15), were found to give metal with usable X-ray diffraction patterns (5). Later, the same method was used to collect Cf metal both on a fused silica fiber for X-ray diffraction analysis and on an electron microscopy grid for electron diffraction analysis 56). As more Cf became available, preparations via this method were carried out on 0.4-1.0-mg samples of californium oxide (55), using fibers of quartz. Be, or C (suitable for direct X-ray diffraction analysis) to collect the product Cf metal. 

Schwartz, M. K., and Bodansky, 0., Use of commercially available preparations of fructose-6-phosphate in the determination of phosphohexose isomerase activity. Anal. Biochem. 11, 48-53 (1965). 

The frequency of application of sunscreen is guided by the SPF (sun protection factor) of the preparation. This derived value is the ratio of the time of ultraviolet exposure that causes erythema with the sunscreen to the time that causes erythema without the sunscreen. The higher the SPF, the less frequent the needed application of sunscreen. SPFs of available preparations vary from 2 to 50. 

Thymic factors are naturally occurring substances that promote T-lymphocyte differentiation and differentiation of early stem cells into prothymocytes. Each of the available preparations (e.g., thymic humoral factor, thymosin fraction 5, and thymodulin) are mixtures of several polypeptides isolated from a calf thymus extract. 

Consequently, commercially available preparations of chlorpromazine and its hydrochloride salt should be protected from light. Chlorpromazine hydrochloride oral solutions, tablets, extended-release capsules and injections should be stored at a temperature less than 40°C, preferably between 15-30°C and in well-closed containers [2]. 

Antihistamines such as diphenhydramine, a mainstay of OTC sleep preparations, are also used widely by parents for their children at doses of 1 mg/kg. Most of the reports of the use of clonidine for sleep disorders are clinical and anecdotal case reports of use in children with ADFFD (Wilens et ah, 1994 Prince et ah, 1996). There are some safety concerns about using clonidine once a day at bedtime, especially in patients who take a daytime stimulant. Melatonin was studied using a double-blind, placebo-controlled, crossover design (Jan et ah, 1994) on a mixed group of 15 children with sleep disturbances, with some improvement reported. However, caution is warranted in using this agent because melatonin is unregulated, and there are concerns about the purity and safety of some commercially available preparations (Werry and Aman, 1999). 

Potentially life threatening effects Some commercially available preparation of pilocarpine contain sodium bisulphite which may cause allergic reactions including anaphylaxis and severe asthmatic episode. 

ITABLE 7.3. Commercially available preparations of human interferon... 

See the Preparations Available section at the end of this chapter for a list of available preparations. These preparations may be synthetic (levothyroxine, liothyronine, liotrix) or of animal origin (desiccated thyroid). 

Commercially available. Prepared by the reaction of triethylphosphite with cyanogen... 

While the preparations of l-(trimethylsilyl)indene and l-(trimethylstannyl)-indene have been reported,4 there are no available preparations of l-(tributyl-stannyl)indene. We chose the tributyl analog because of the decreased toxicity of tributyltin reagents vs. trimethyltin reagents.5 A preparation for the synthesis of Mg(C9H7)2, another indenyl transfer agent, has appeared in Inorganic Syntheses.6... 

If no recorder tracing is available, prepare a graph of pH vs. time for each experiment. Prepare and complete a table with the following headings ... 

Several methods for preparation of purified venom exonuclease have been described [see the reviews on methods (15, 18, 19, 21) and books (22-24)]. The major effort of purification was directed toward removing the contaminating monophosphatases. A successful and widely used step was introduced by Sinsheimer and Koerner (43). At pH 4, monophosphatases are precipitated with a lower concentration of acetone the remaining exonuclease is precipitated by a higher acetone concentration. Several modifications of this principle have been proposed (concentration of acetone, temperature during precipitation, etc.). Commercially available preparations represent essentially this stage and contain per unit of exonuclease 10 4 unit of 5 -nucleotidase, 10 3 unit of nonspecific phosphatase, and about the same amount of endonuclease. The last figure is only an approximation because of the difficulty of accurate determination. The more elaborate preparations have these contaminants... 

The available preparations for IFN-p-la include Avonex and Rebif, both synthesized by recombinant DNA technology. They are similar but Rebif is administered more frequently and at a higher dose. A third preparation, Betaseron, is IFN-p-lb. 

The earliest available preparations, made as infusions and concentrated to a syrup by the native people, were designated as calabash (gourd), tubo- (bamboo), or pot (clay pot) curare depending upon the containers in which the drug was packaged. Curare is obtained from the upper regions of the Amazon river, the Orinoco basin, and the eastern slopes of the Ecuadorian plateau. The term curare is derived from the Indian name (woorari, urari) for poison (Grollman, 1962). 

Because melatonin is not regulated by the FDA, commercially available preparations are not subject to the same scrutiny as medications under the direction of this federal agency. Melatonin supplements do not have to be extensively tested in animals and humans before being sold in over-the-counter preparations. Manufacturers do not have to maintain high production standards, nor do they have to be as concerned with instituting FDA-required safety checks. Manufacturers are, however, limited by law in one way They cannot claim that their product will cure or treat anything. They can only make general statements. While they can say that melatonin helps people sleep, they cannot say that it treats insomnia. 

While many commercially available preparations contain only melatonin, many others contain a combination of this hormone with other active ingredients. Some of these other ingredients may be vitamins such as pyri-doxine, while others are natural remedies such as kava root and valerian. It is even available combined with acetaminophen, a common over-the-counter pain reliever. Frequently, the long-term effects and safety of these other ingredients are not known. Even less is known about any possible interactions between these substances and melatonin, because melatonin has been available and used commercially for only a short period of time. Many experts have suggested that it would be preferable to test melatonin in controlled studies to determine if it is effective and safe before it was released on the market and used by millions of people. 

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