The Esophagus

The esophagus is approximately 40 cm long in the adult, passing through the diaphragm at approximately 38 cm. The surface of the esophagus is a squamous epithelium with a protective function as in the mouth and has few if any glands. The morphology changes sharply at the junction with the stomach into secretory epithelium.

After the dosage form leaves the buccal cavity, movement through the esophagus is normally complete within 10 s. The voluntary maneuver is handed over to a complex autonomic sequence in the cricopharynx, followed after swallowing by short secondary peristaltic waves, which serves to attempt to clear the esophagus. The efficiency of clearance may be influenced by several factors, including the outside surface of the dosage form, the age of the subject and pre-existing disease. Conditions such as type 1 diabetes reduce the amplitude of peristaltic waves and further exacerbate the problems of esophageal clearance, particularly for solid swallows [2]. The elderly often report problems in attempting to swallow

Fig. 2.5 General plan of buccal physiology. Note that the tissues at the top of the mouth are much less permeable than the sublingual area. Buccal systems are used along the gum margin and cheeks and are generally sustained delivery systems, whereas sublingual systems are fast release, as they cannot be anchored

Fig. 2.5 General plan of buccal physiology. Note that the tissues at the top of the mouth are much less permeable than the sublingual area. Buccal systems are used along the gum margin and cheeks and are generally sustained delivery systems, whereas sublingual systems are fast release, as they cannot be anchored large objects, in part influenced by previous unsuccessful attempts but influenced by the increased stiffness and lower muscle compliance. The elderly have little "swallowing reserve" but experience fewer problems in clearing a liquid bolus compared to a solid mass. It is a common practice in nursing homes to crush medications for dysphagic patients, despite the fact that controlled release formulations are specifically designed not to be damaged prior to ingestion. Although, large tablets are commonly identified as problematic, small flat and buoyant dosage forms are particularly likely to cause problems in the elderly because of the inability to complete the swallowing maneuver.

The coating of tablets to identify the product, to protect the integrity of the dose or to mask bitterness or appearance is a principal activity in the manufacture of oral formulations. The film coat can be functional as for enteric release products or esthetically pleasing and the mouth feel emphasizes the "swallowability" of the product. Channer and Virjee (1985) showed that the clearance of plain, sugar-coated, enteric-coated and film coated tablets in 34 patients was strongly influenced by coating and by posture [3]. The authors reported 100% clearance of film coated tablets in 13 s; for the plain uncoated formulation full clearance was observed in only 60% of subjects at this time. The findings also confirmed their earlier report that oval coated tablets showed the fastest esophageal transit in the erect position, even when swallowed with low volumes of water [4]. A recent interesting article nicely illustrates the importance of shape factors and organoleptic issues on the swallowing of large dosage forms [5].

Was this article helpful?

0 0
Diabetes 2

Diabetes 2

Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...

Get My Free Ebook


Post a comment