Rectal administration route advantages

Drugs are most commonly administered orally, topically or by injection (both intravenous and intra muscular). However, another potentially useful though less common route is via the lower rectum. Advantages of rectal administration over oral administration are ... 

Drugs administered by rectal route. Advantages of the rectal ronte for drug administration are as follows ... 

To achieve a reasonable degree of absorption, peptide and protein pharmaceuticals may need permeation enhancers to promote passage across mucosal cells. Another concern is that studies of insulin and enkephalin in animals suggest that protease activity may be high, especially in the rectal cavity [5,6]. On the other hand, the density of lymphatic vessels and drainage therein at these sites may be advantageous compared with other routes of administration. 

The administration of drugs by alternative routes avoids absorption and metabolic barriers that may be present in the GI tract. The routes can also provide systematic availability when oral administration is contraindicated due to a physiologic condition, or the route may provide for a concentration-time profile that approaches intravenous dosing profiles. The ophthalmic, nasal, pulmonary, buccal, transdermal, and rectal routes provide one or more of these advantages. 

Due to its greater anesthetic potency and more favorable side effects profile, S-ketamine has supplanted racemate in several European countries [204], In a study examining the utility of the S enantiomer preoperative medication in pediatric patients [204], the enantiomer was given by the rectal route to 40 children with or without midazolam. Another 22 children were premedicated only with midazolam. The authors found that S-ketamine had no advantage over midazolam alone as a preoperative sedative, and that S-ketamine was much less effective than had been observed previously in a similar cohort of subjects given racemic ketamine. The authors speculated [204] that perhaps the enantiomers are absorbed differently by the rectal route of administration. 

Sometimes other routes of administration are necessary. Thus, suppositories are used for rectal delivery and sprays for the nasal route. Sublingual delivery can be advantageous, e.g., for nitrate esters. For asthma the use of inhalators has increased considerably as reliable hi-tech delivery systems have been developed. Flere, the uniformity of the inhaled dose (usually a few micrograms), as well as the narrowness of the particle size distribution, must be safeguarded. 

Suppository is solid-like preparation made from drug and suitable bases for cavity administration. When inserted into cavities, they melt or soften, after which drug dissolution and absorption result in local or systemic effect. Whin rectal suppository is a common form which is usually used as laxatives. Administrated by rectum mucosa, suppositories possess many advantages compared with oral route. Firstly, it is a convenient administration way for infants or patients suffering from vomiting or gastrointestinal disturbances. 

The rectal cavity has the potential of convenient access and easy administration of suppositories or gels, although patient acceptance of rectal delivery is low in some cultures. It has a limited surface area (de Boer et al, 1992) and relatively high proteolytic activity (Lee et al, 1987), but with respect to administration of insulin the rectal route offers the particular physiological advantage of potential delivery, via the upper rectal veins, into the portal system. This would mimic the natural secretion of insulin and result in reduced peripheral hyperinsulinemia. However, nearly two-thirds of the insulin absorbed firom the rectum reaches the general circulation via the lymphatic pathway (Caldwell et al, 1982). 

Ease of use morphine and all the other injectable opioids are very easy to use. One major advantage of morphine that leads to its ease of use is the multiple routes of administration (IV, IM, SQ, IT epidural, intraventricular, rectal, oral, and inhalational). Morphine can easily be titrated to sedation levels, pain scores, and respiratory rate. 

The rectal route offers an alternative to the oral route of administration and offers some advantages in experimental work. Drug absorption from the rectum (of the... 

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