Rectal (mucosal) delivery of peptide / protein drugs :

Rectal delivery of peptides and protein drugs is another very active area of research.

Rectal delivery offers many advantages including-

- Avoidance of drug absorption prior to reaching the systemic circulation and of drug contact with digestive fluids and consequential degradation.

- The rate of drug absorption via. the rectum is not influenced by ingestion of food or the rate of gastric emptying.

- Reduction in first - pass metabolism.

- Rapid systemic absorption by administering the drug rectally in a suitable solution form.

- Safe and convenient especially for infants and children.

- Drug absorption can be interrupted in case of accidental overdose or drug reaction.

1. Factors affecting drug availability rectally-

Rectal fluid-

- Amount

- Composition

- pH

- Buffer capacity

- Surface tension

- Viscosity

- Luminal pressure

Drug substance-

- Solubility

- Surface properties

- Particle size

- Drug concentration

- pKa

Vehicle-

- Composition

- Fusion behavior

- Surface tension

- Rheological behavior

The extent of breakdown of peptides is low in the lower digestive tract relative to the small intestine and the stomach, due to low enzymatic activity and neutral pH. Reports on peptide and protein drugs delivered by the rectal route include insulin, calcitonin, gastrin, pentagastrin, human growth hormone and vassopressin.

In the next chapter, let us discuss mucosal DDS by the colon-targeted route.

For an expert opinion on formulation development of peptide/ protein molecules http://www.drshrutibhat.com

My other blog that might be of interest- http://www.qa-expert.com/