Evaluation of alternate routes for delivery of leuprolide

Nasal administration of opioids for pain management in adults

BACKGROUND

Nasal administration of opioids may be an alternative route to intravenous, subcutaneous, oral transmucosal, oral or rectal administration in some patients. Key features may be self-administration, combined with rapid onset of action. The aim of this paper is to evaluate the present base of knowledge on this topic.

METHODS

The review is based on human studies found in Medline or in the reference list of these papers. The physiology of the nasal mucosa and some pharmaceutical aspects of nasal administration are described. The design of each study is described, but not systematically evaluated.

RESULTS

Pharmacokinetic studies in volunteers are reported for fentanyl, alfentanil, sufentanil, butorphanol, oxycodone and buprenorphine. Mean times for achieving maximum serum concentrations vary from 5 to 50 min, while mean figures for bioavailability vary from 46 to 71%. Fentanyl, pethidine and butorphanol have been studied for postoperative pain. Mean onset times vary from 12 to 22 min and times to peak effect from 24 to 60 min. There is considerable interindividual variation in pharmacokinetics and clinical outcome. This may partly be due to lack of optimization of nasal formulations. Patient-controlled nasal analgesia is an effective alternative to intravenous PCA. Adverse effects are mainly those related to the opioids themselves, rather than to nasal administration. Some experience with nasal opioids in outpatients and for chronic pain has also been reported.

CONCLUSION

Nasal administration of opioids has promising features, but is still in its infancy. Adequately designed clinical studies are needed. Improvements of nasal sprayer devices and opioid formulations may improve clinical outcome.

Transport of peptide and protein drugs across biological membranes

The transport characteristics of peptide and proteins drugs across various epithelial membrane barriers are outlines. These include transport through the intestinal, buccal, nasal and pulmonary absorptive mucosae, as well as transdermal penetration. Because peptides and proteins are hydrophilic and high molecular weight compounds, they commonly show minor permeability across the mentioned biological membranes. In order to improve their transport properties and thereby their systemic bioavailability, several strategies can be undertaken, such as the synthesis of stabilized and lipophilic analogues, the application of absorption enhancers and protease inhibitors, and the design of suitable dosage forms (e.g., liposomes, biodegradable nanocapsules, bioadhesive microspheres).