Routes of drug delivery

J. S. Patton and R. M. Platz, Routes of drug delivery case studies (2) pulmonary delivery of peptides and proteins for systemic action, Adv. Drug Deliv. Rev, 8, 179 (1992). 

Hoogstraate AJ, Bodde HE (1993) Methods for assessing the buccal mucosa as a route of drug delivery. Adv Drug Del Rev 12 99-125... 

To modulate the rate and extent of therapeutic protein exposure in target tissues, scientists have considered other routes of administration. These alternative routes of drug delivery will be discussed below. All available data suggest that protein bioavailability is expected to be low for nonparenteral routes of administration (i.e., less than 10%). 

The nasal route of drug delivery is used for the direct administration of medicines to the nose for treatment of local conditions or the systemic delivery of compounds that are not easily delivered by the oral route. It is also suggested that there may be a direct route for drug absorption to the central nervous system (CNS) from the olfactory region of the nose. 

Richardson, J.L., and L. Ilium. 1992. Routes of drug delivery Case studies. The vaginal route of peptide and protein drug delivery. Adv Drug Deliv Rev 8 341. 

Buccal mucosal permeability also varies with the anatomical site for example, keratinized sites of the oral cavity hinder the permeation of hydrophilic molecules.96 Therefore, it is important to consider these factors in selecting the transmucosal route for drug delivery in the oral cavity. A limited surface area (100 to 170 cm2) and the need to mask taste for bitter drugs are some of the drawbacks associated with this route of drug delivery. 

The nasal route of drug delivery avoids the liver first-pass effect, but the pseudo-first-pass effect owing to nasal metabolism of drugs is still a concern. Many enzymes such as carboxylesterase, aldehyde dehydrogenase, glutathione transferases, UDP-glucoronyl transferase, epoxide hydrolases, CYP-dependent monoxygenases, exo- and endopeptidases and proteases are present in the nasal mucosa.106 108,110,116 CYP enzymes are present abundantly in the olfactory epithelium.107,110... 

Although the oral route is the most common route of drug delivery, investigation into the prediction of uptake by other routes is also important. Dermal penetration and inhalation are not only relevant as methods of drug delivery, but in terms of toxicology they represent important routes of exposure. 

Methods to achieve drug targeting are introduced in Chapter 3 (Section 3.3), discussed in detail in Chapter 5 with respect to the parenteral route and also in further chapters concerning the various routes of drug delivery. 

The various routes of drug delivery are discussed in detail in subsequent chapters the description below constitutes a brief introductory outline. 

The chapters in Section 2 concerning the various routes of drug delivery have been edited with particular care to ensure that the treatment of each particular route follows a common format. This has been undertaken not only to ease understanding and facilitate learning but also to highlight the many similarities that exist between the various routes, as well as the unique attributes associated with each specific route. 

Gopinath, P. G., Gopinath, G., and Kumar, T. C. A. (1978), Target site of intranasally sprayed substances and their transport across the nasal mucosa. A new insight into the intranasal route of drug delivery, Curr. Ther. Res., 23, 596-607. 

Because poor bioavailability represents one of the principal causes of compound failure, absorption and metabolism assays feature prominently in lead optimization screens. As oral administration represents the ideal route of drug delivery, models that predict low absorption across the gastrointestinal (GI) tract are commonly employed. Caco-2 cell assays have been... 

The lungs have been a route of drug delivery for millennia. Modern medical applications of aerosol delivery can be traced to the development of the pMDI in the middle of the twentieth century.19... 

Despite disadvantages, the oral route remains the preferred route of drug delivery. Several improvements have taken place in the formulation of drugs for oral delivery for improving their action. 

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