Info

Seated14

Typical transit times

Normally, the oesophageal transit of dose forms is extremely rapid, usually of the order of

10 to 14 seconds. Typical transit times for various pharmaceutical dosage forms are shown in Table 4.1

These data suggest that large oval tablets have a shorter oesophageal transit than large round tablets, but the influence of size and shape of formulations on oesophageal transit is insignificant when compared to the influence of the posture of the subject. Oesophageal transit is slower in supine patients than upright ones. Although studies are often carried out in supine patients to eliminate the effects of gravity, the differences in oesophageal transit produced with varying size and shape of a tablet are only observed in upright subjects and not supine ones. Interestingly, the transit of a heavy capsule is significantly faster than a light capsule in erect subjects, but the order is reversed in supine subjects15. The transit of large but not small capsules is significantly faster than plain oval tablets in both erect and supine volunteers15.

Bolus composition can at markedly affect transit. Liquids clear rapidly, with one swallow regardless of whether the subjects were supine or seated, but capsules or liver cubes when ingested without water, frequently remained in the oesophagus up to 2 hours after administration, without the subject being aware of their presence13.

Swallowed

Dissolution From Surface

Oesophageal — Mucosa

Local Dehydration

1 .odged Tablet

Swallowed

Oesophageal — Mucosa

Dissolution From Surface

Local Dehydration

Gel ^ Formation

1 .odged Tablet

(Esophageal Mucus

Figure 4.5 Mechanism of adhesion of a dosage form

Was this article helpful?

0 0
Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

Get My Free Ebook


Post a comment