Salt forms, active substances

Membranes and Osmosis. Membranes based on PEI can be used for the dehydration of organic solvents such as 2-propanol, methyl ethyl ketone, and toluene (451), and for concentrating seawater (452—454). On exposure to ultrasound waves, aqueous PEI salt solutions and brominated poly(2,6-dimethylphenylene oxide) form stable emulsions from which it is possible to cast membranes in which submicrometer capsules of the salt solution ate embedded (455). The rate of release of the salt solution can be altered by surface—active substances. In membranes, PEI can act as a proton source in the generation of a photocurrent (456). The formation of a PEI coating on ion-exchange membranes modifies the transport properties and results in permanent selectivity of the membrane (457). The electrochemical testing of salts (458) is another possible appHcation of PEI. 

Quaternary salts of the substances represented by tliese formulae have been prepared by Kogl, Veldstra and van der Laan as well as of the next lower homologues, the substituted butyraldehydes, and the methyl ethers of both series. Their pharmacological activities were negligible in comparison with that of muscarine, but as six stereoisomeric forms may be produced in each synthesis, the inactivity may be due to stereoisomerism, just as in the case of threonine (a-amino-)3-hydroxy-butyric acid) where West and Carter found that only the d —) form is... 

The different salts, esters, ethers, isomers, mixtures of isomers, complexes or derivatives of an active substance shall be considered to be the same active substance, unless they differ significantly in properties with regard to safety and/or efficacy, in which case additional safety and efficacy data are required. The same qualitative and quantitative composition only applies to the active ingredients. Differences in excipients will be accepted unless there is concern that they may substantially alter the safety or efficacy. The same pharmaceutical form must take into account both the form in which it is presented and the form in which it is administered. Various immediate-release oral forms, which would include tablets, capsules, oral solutions and suspensions, shall be considered the same pharmaceutical form for this purpose. 

FORMATION. Aqueous solutions of highly surface-active substances spontaneously tend to reduce interfacial energy of solute-solvent interactions by forming micelles. The critical micelle concentration (or, c.m.c.) is the threshold surfactant concentration, above which micelle formation (also known as micellization) is highly favorable. For sodium dodecyl sulfate, the c.m.c. is 5.6 mM at 0.01 M NaCl or about 3.1 mM at 0.03 M NaCl. The lower c.m.c. observed at higher salt concentration results from a reduction in repulsive forces among the ionic head groups on the surface of micelles made up of ionic surfactants. As would be expected for any entropy-driven process, micelle formation is less favorable as the temperature is lowered. 

The racemic mixture are separated into their individual, substantially optically pure isomers through well-known techniques such as, for example, the separation of diastereomeric salts formed with optically active adjuncts, e.g. acids or bases followed by conversion back to the optically active substances. So the 4-acethylamino-5-amino-3-(l-ethyl-propoxy)-cyclohex-l-ene-l-carboxyllic acid ethyl ester,(3a,4p,5a) was obtained. 

Because of these reactions the distillation of persulphuric acid and persulphate solutions present a difficult technical problem. First of all, the solutions used for the distillation must be as free as possible of catalytically active substances (such as salts of iron, manganese, copper etc.) as they would considerably promote the decomposition of peroxide. Secondly, satisfactory results require a sufficiently high rate of distillation. A quick heating of the solution to boiling point and a quick removal of the vapours formed from the distillation space means that the time during which the peroxide is in eontact with the persulphuric and Caro s acid and the time of the catalyst action are considerably... 

The members of the second subgroup are prepared from ethylene diamine (20) or its derivatives by reaction with carbon disulfide. In a sodium hydroxyde medium the disodium salt nabam, in an ammonium hydroxide medium, the diammonium salt amobam is formed (21). The sodium-ammonium salt, nambam, can also be prepared. These active substances are soluble in water. They cannot be used as foliage fungicides because of their phytotoxicity. On the other hand, they can be applied with good results for seed treatment. These compounds are intermediate products of the water-insoluble metal salts of N,N-ethylene-bisdithiocarbamic acid. c... 

Of the dialkyldithiocarbamates belonging to the second group of dithiocar-bamates, dimethyidithiocarbamates have the highest activity. With an increase of the alkyl group fungitoxity is rapidly reduced. The compounds are prepared by the reaction of dimethylamine with carbon disulfide and alkali hydroxide. The individual active substance can be obtained by the addition of the alkali salt formed. 

N,N-Dimethyldithiocarbamates do not form isothiocyanates, so their mode of action as fungicides is different from that of the afore-mentioned substances. TMTD penetrates the cell membrane of fungi more easily than dimethyldithio-carbamates, and is then reduced within the cell (Richardson and Thorn, 1961) so that its action is the same as that of dimethyldithiocarbamates. However, the fact that TMTD is more toxic to several microorganisms than the sodium salt of dimethyidithiocarbamic acid indicates that there must be a certain nonessential difference between the two active substances. Owens and Rubinstein (1964) proved in vitro the different reactivity of TMTD and of the other dimethyldithiocarbamates towards 4-nitrothiophenol. However, in the primary reaction of TMTD dimethyl-... 

With a view to the relationship between the structure and action of glyodin, the research in the benzimidazole series was first centred on active substances containing long alkyl chains. Of these, l-methyl-2-phenyl-3-dodecylbenzimidazolium ion has been used in plant protection in the form of its insoluble salts. These salts such as the... 

Liver Extract Kyer89 prepared a concentrated liver extract by precipitating the proteins with lead acetate and then adsorbing the active principle on carbon. The use of the lead salt had certain disadvantages in a later method, calcium chloride and sodium carbonate were added to form a precipitate of calcium carbonate which removed the protein as did lead acetate. The filtrate adjusted to pH 5 is treated with activated carbon, and the filtrate from this is treated with an additional quantity of carbon. The carbon cakes are extracted with hot 50% alcohol and the eluate is concentrated in vacuo. Tyrosine also is adsorbed and eluted with the active substance, although, with some carbons, the adsorption of tyrosine is incomplete. 

Not all of the surfactants are capable of forming micelles. The appropriate ratio between the size of hydrophobic (hydrocarbon chains) and hydrophilic (polar group) parts of surfactant molecules, which determines their hydrophile-lipophile balance (HLB, see Chapter VIII, 3), is necessary for the formation of micelles to take place. Sodium and ammonium salts of C12 - C20 fatty acids, alkylsulfates, alkylbenzenesulfonates, and other synthetic ionic and nonionic surfactants are the examples of micelle-forming surface active substances. The true solubility, i.e. the concentration of dissolved substance in its molecular or ionic form, of such surfactants is rather low for ionic surfactants it is on the order of hundredths and thousandths of kmol m 3, while for nonionic ones it can be even lower by one or two orders of magnitude. 

The sodium salt of 3-(((3-(2-(7-chloro-2-quinolinyl)ethenyl)phenyl)((3-dimethylamino)-3-oxo-propyl)thio)propanoic acid represents an unusual case of a hygroscopic drug substance, where the surface-active substance (in both crystalline and lyophilized forms) produced nonflowing, semisolid masses with exposure to increasing relative humidity [29]. The substance was shown to form first an amorphous material and then a mesomorphic phase, as the moisture sorption increased with exposure to relative humidity. 

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