Oral micro-organisms

Active agents vary according to use. For controlling bad breath, zinc salts, sodium lauryl sulfate, and flavors are used. To destroy oral micro-organisms, chlorhexidine, cetyl-pyridinium chloride [123-03-5], and benzalkonium chloride [68391-01-5] are valuable. Essential oils, such as thymol [89-83-8], eucalyptol [470-82-6], menthol, and methyl salicylate [119-36-8] reduce plaque-related gingivitis. Sodium fluoride aids in caries control. 

Application of sialidase inhibitors for medical use is still in a premature state. It is imaginable that inhibitors would be useful drugs in infections, caused by micro-organisms, that lead to extensive production of sialidase, for example, in gas edema.371 In the oral cavity, plaque formation and dental caries may be influenced by desialylation of salivary glycoconjugates,399 and bacterial sialidases may play a role therein. This process may be retarded by secretion of the inhibitor Neu2en5Ac in saliva at concentrations which, in some cases, were found to be close to the K value for sialidases.34... 

Particular difficulties exist, however, in purifying dextrans synthesized by many streptococci, because the bacteria simultaneously elaborate exocellular fructans (levansDextrans and levans synthesized concomitantly by Leuconostoc micro-organisms have been separated by fractionally precipitating the polysaccharides from aqueous ethanol. These separative procedures are, however, only effective when considerable differences in molecular weight exist between the main fractions of the two polysaccharides, and, as a result, they are of limited value in effecting separation of levans from many streptococcal dextrans. Reports that some oral bacteria are able to metabolize levans suggest that... 

Usually purified water (Aqua purificata) is used. Because of the chemical and microbiological quality it is preferred over potable water (see Sect. 20.3.1) although the taste of potable water may be better due to presence of ions. Water is a good growth medium for micro-organisms, so aqueous oral liquids generally have to be preserved, see Sect. 5.4.9. 

Water supports the growth of micro-organisms, therefore oral aqueous solutions, suspensions, emulsions and solubilisates in multidose containers should be preserved. Preservatives may be used for that purpose as well as excipients with preservative properties, such as propylene glycol. See Sect. 23.8 for extensive information on preservatives. Table 5.18 summarises preservatives with properties especially relevant for oral liquids. 

Micro-organisms exist in numerous forms and shapes, so for every (extreme) pH value, types can be found that are able to survive and replicate under those specific conditions. However, micro-organisms that are commonly encountered during the preparation and use of pharmaceutical preparations do not grow outside the pH range of 3-9. There are a few examples of preparations with a pH outside this range, for example a ferrous chloride oral solution (pH 1.5) (Table 22.9) and a theophylline oral solution 30 mg/mL (pH 9.5) (Table 22.10). Such preparations thus require no preservation. 

Micro-organisms highly sensitive to inhibition by rifampin, include penicillin-sensitive as well as penicillin-resistant S. aureu , D. neu-moniae, group A streptococci, H. influenzae Proteus, M. tuberculosis in vitroand,in the mouse. Plasma levels above 2 pg/ml were attained in man between two and four hours after oral administration of a 300 mg dose of rifampin. A major portion of the drug is found in the bile in the form of 25-desacetyl rifampin with evidence of entero-hepatic circulation of this biologically active metabolite. 

Leuprolide acetate, a synthetic nonapeptide, is prescribed for the treatment of metastatic prostate cancer and endometriosis. Leuprolide acetate is presented in a number of injectable dosage forms including Lupron sterile solution for subcutaneous administration (1 and 5 mg mL 1) and Lupron depot controlled release formulation for intramuscular injection (3.75 and 7.5 mg). Zheng and Fulu [106] have evaluated the in vivo effect of leuprolide loaded micro emulsions on the genital organs of the male and female rats. In the preliminary pharmacokinetic studies, oral microemulsions of leuprolide administration resulted in 10-fold higher plasma levels of leuprolide as compared to that of saline solution (Fig. 9.4). 

Micro and nano-particles nsed for oral administration of drugs are solvent cast using water or organic solvents. The stirring rate and temperature under which the particles are processed greatly affects their dmg release rate and degradation properties. 

The occnrrence of a mucus layer that present at the surface of various organs has been exploited to develop mucoadhesive dosage forms. These layers act as administration site to prolong time, and increase the local and/or systemic bioavailability of the administered drug [58]. The appearance of micro and nanotechnologies simultaneously with the execution of non-invasive and painless administration routes has transforms the pharmaceutical market and the management of disease. Intending to minimize the chief limitations of the oral route and... 

Rohanizadeh, R. et al. (1998) Ultra-structural organization and micro-analysis studies of deciduous enamel crystallites in regional odontodysplasia (RO). J. Oral Pathol. Med., 27 (10), 501-507. 

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