Oral mucosal membranes

Oral mucosal membranes provide a port for systemic therapy as weU. Nitroglycerin sublingual tablets (Nitrostat) abort acute mgina attacks methyl-testosterone [58-18-4] buccal tablets (Android 5) are indicated for testosterone [58-22-0] replacement therapy (39) md nicotine [54-11-5] gum (Nicorette) aids in smoking cessation. 

There are clear differences between the oral mucosal membrane and other epithelial membranes of the intestine, nasal cavity and rectum. The oral mucosal membranes are less keratinized than the skin membranes and show a more loosely packed intercellular lipid domain. In terms of function of the absorption enhancement through the oral mucosal membrane, it can be said that it occurs principally through the... 

There are only a limited number of studies comparing the systematic changes in the structure of enhancers and their influence on the oral mucosal membranes. For example, for insulin absorption in rats, it was shown that sodium glycocholate, laureth-9, sodium laurate, and sodium lauryl sulphate were approximately equipotent. Several non-ionic surfactants having a Ci2 hydrophobic tail were much less effective.P 24]... 

Factors affecting absorption from the oral mucosal membranes include lipid solubility and molecular weight of the drug, pH of the saliva and the rate of removal by the blood as well as the application of the correct technique. 

A woman who came into contact with several cephalosporins developed contact dermatitis lesions on the eyelids as well as pruritus and dryness of the nasal and oral mucosal membranes. Patch testing revealed positive reactions to cephalothin, cefamandole, and cefazolin (Conde-Salazar et al. 1986). Cephradine has also been described as a cause of occupational dermatitis in the pharmaceutical industry by Rudzki et al. (1989). Although cross-sensitivity with penicillins is possible (Martindale 1993), this was not reported in these cases. 

The lateral resolution of 0.5 allows experiments at the subcellular level. Initial work has concentrated on the localization of elements In specific sites of the tissue. Typical examples involve the assessment of aluminium levels in the bones of chronic haemodialysis patients, the study of lead accumulation in kidneys and calcifications in intraperitoneal soft tissue as a result of chronic lead intoxication, and the detection of several heavy metals in the amalgam tattoos of the oral mucose membrane and human gingiva in direct contact with dental alloys. The relatively low lateral resolution, the lack of automated mapping and the almost impossible quantization strongly hinder the use of LMMS, especially in view of analytical electron microscopy (AEM) with X-ray analysis and the emerging possibilities of nuclear microscopy. 

Human exposure to bromomethane is most likely to occur by inhalation or dermal contact (see Chapter 5). Inhalation exposure may cause neurological, respiratory and renal damage. Dermal contact may cause skin lesions while oral exposure leads to digestive tract mucosal membrane irritation (see Section 2.2). 

Calcium play vital role in excitation - contraction coupling in myocardium. Calcium mediates contraction in vascular and other smooth muscles. Calcium is required for exocytosis and also involved in neurotransmitters release. Calcium also help in maintaining integrity of mucosal membranes and mediating cell adhesions. Hypercalcemia may occur in hyperthyroidism, vitamin D intoxication and renal insufficiency, which can be treated by administration of calcitonin, edetate sodium, oral phosphate etc. Hypocalcemia may occur in hypothyroidism, malabsorption, osteomalacia secondary to leak of vitamin D or vitamin D resistance, pancreatitis and renal failure. Hypocalcemia can be treated by chloride, gluconate, gluceptate, lactate and carbonate salts of calcium. 

For oral delivery, complexes will also dissociate rapidly on dilution in the stomach and intestinal contents and it is generally believed that only the drug, and not the complex, is absorbed (Thompson, 1997). Therefore, the primary function of complexes is to increase the dissolution rate and extent of drug dissolution. Other reported effects of CDs on oral absorption of drugs include enhancement of mucosal membrane permeation by CD as mentioned earlier in this chapter. 

The varying structure of the mucosal membrane in different parts of the oral cavity and the reduced permeation due to the barrier presented by the mucosal epithelial layers... 

There is a vogue for many scientifically nonqualified aromatherapists to practice clinical aromatherapy, in which they prescribe the internal usage of essential oils. Internal prescribing involves oral, rectal, and vaginal intake however, the use of tampons soaked in various potentially toxic essential oils, such as the various tea tree oils, with variable biological potential could have a possible harmful effect on the delicate internal mucosal membranes. The possibility of misdiagnosis of a urogenital condition by medically unqualified aromatherapists or by the patients themselves could also result in serious consequences. 

Absorption can be enhanced via several mechanisms. These include increased membrane fluidity, chelation of the calcium ions that serve to maintain the dimension of the intercellular space, solubilization of the mucosal membrane, enhancement in water flux, and reduction of the viscosity of the mucus layer adhering to the epithelial cells. A discussion of various types of pentration enhancers and their mechanism (s) of action is given in Chapter 8 (Section 8.7.1). Table 6.4 summarises the oral absorption enhancers that have been tested for oral dmg delivery. 

Azone (l-Dodecylazacycloheptan-2-one) and related compounds have been studied as transdermal penetration and oral absorption enhancers. Although some efficacy has been shown, an emulsifying agent appears to be necessary for azone to penetrate the intestinal mucosal membrane in order to promote drug absorption. One study reported the absence of gross morphological damage after exposure of mucosa to azone but additional information on the effect of azone on overall mucosa structure is not avalable. 

Trivalent Oral Polio Vaccine (TOPV)- TOPV (Sabin vaccine. I960) is a live attenuated whole virus vaccine (antigen type, protein) containing polio strains I. 2. and 3. The virus culture is grown on monkey kidney tissue with use of an elaborate attenuation protocol. Oral administration of the vaccine yields a local Gl infection, and the initial immune respon.se is via IgA (mucosal, local to the Gl tract). The IgA-antigen complex undergoes transcytosis across the mucosal membrane, and systemic immunity is induced as IgM and IgG form. A major caution with TOPV is that it is a live vaccine and must never be injected. Indications ore... 

Mucosal membrane pigmentation Oral mucosal eruption Tongue pigmentation... 

Mucosal membrane desquamation Oral lesions Oral ulceration Stomatitis... 

Mucocutaneous syndrome Mucosal membrane pigmentation Oral mucosal fixed eruption (1982) Murray VK+, j Periodontology 53, 267 Oral ulceration... 

We will refer to oral absorption as the movement of dmg across the outer mucosal membranes of the GI tract [112], whereas oral bioavailability is that fraction of the dose that reaches the general circulation unchanged [113]. The general circulation is defined experimentally in terms of a blood vessel in the peripheral circulation. 

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