Drugs online research references
Am J Clin Pathol. 1978 Nov;70(5):821-5.
Aerobic and anaerobic susceptibility tests with three tetracyclines. Reassessment of the "class concept" of disk testing.
Barry AL, Draper DL, Wong MK.
Both aerobic and anaerobic susceptibility tests were performed with tetracycline, doxycycline, and minocycline, using disk diffusion and agar dilution technics. The data were examined in order to reassess the concept of testing a single disk, representative of the tetracycline class of antimicrobics. All strains that were susceptible to a tetracycline disk were predictably susceptible to the tetracycline analogs. Some strains that gave zones in the resistant or intermediate range were susceptible or moderately susceptible to doxycycline and minocycline by agar dilution methods. However, disk tests with the more active analogs were often unproductive, since most tetracycline-resistant strains gave indeterminate results with doxycycline or minocycline disks. It was concluded that the "class concept" of disk testing is still appropriate and that tests with tetracycline disks predict susceptibility to the other tetracycline analogs reasonably well.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=717289&dopt=Abstract
Immun Infekt. 1982 Sep;10(5):193-201.
[Comparative analysis of tetracycline, doxycycline and minocycline on chromosomal and plasmid tetracycline-resistant and -sensitive strains of Staphylococcus aureus using MIC, microcalorimetric effect and ultrastructural alterations]
[Article in German]
Lebek G, Semenitz E, Gstraunthaler G, Pfaller W.
A staphylococcus aureus strain of a patient with plasmidical tetracyclinresistance has first been cured from the plasmid and after that selected in nutritive broth by increasing the concentrations of tetracyclin. By this way we found three variants of the same strain: a tetracyclin-sensitive and two tetracyclin-resistant: an R-plasmid-mediated and the other as a result of mutation. These three variants have been tested against tetracyclin, minocyclin and doxycyclin on an agarmedium. Under influence of these three substances a microcalorimetrical investigation of the strains has taken place. We then tested the strains with the electronic microscope for alterations in the ultra-structure by the three substances. Following results have been obtained: 1. The sensitive strains were inhibited in the same extent by all of the three substances. Plasmidical resistant strains were only resistant against tetracyclin but not against minocyclin and even less against doxycyclin. 2. The microcalorimetrical tests confirmed the conclusions from the cultural test. 3. Alterations in ultra-structure were only found under tetracyclin-influence by strains in division. Comparing the three tetracyclines we did not find any significant difference in quality. 4. With all of the three investigation-methods we proved that R-plasmid-mediated tetracyclin-resistance of staphylococci is not effective for minocyclin and even less for doxycyclin.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7173974&dopt=Abstract
Pol J Pharmacol Pharm. 1982 Nov-Dec;34(5-6):409-21.
Kinetics of drug decomposition. Part 74. Kinetics of degradation of minocycline in aqueous solution.
Pawelczyk E, Matlak B.
Under anaerobic conditions within the pH range 0.38-9.35 (at 343 K) and in the presence of air oxygen within the pH range 0.83-5.42 (at 323 K) the degradation of minocycline (MC) in aqueous solutions follows the first order kinetics. In neutral and alkaline solutions in the presence of air oxygen the autocatalytic first order reaction takes place. The degradation of MC both under anaerobic and aerobic conditions is catalyzed by buffer components of formate, acetate, phosphate and borate buffers. Under anaerobic conditions the degradation of MC is a result of water evoked spontaneous reaction. The rate of this reaction depends on the charge of MC. The specific rate constants of degradation for particular ionic species of MC under anaerobic conditions have been determined. The rate of oxidation of MC is also charge-dependent. The most susceptible to oxidation are the ionic species MC+-, MC+-- and MC--. Effects of temperature, metal ions and stabilizers on the stability of MC were also investigated.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7187051&dopt=Abstract
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