Absorption enhancement of a protein drug by nitric oxide donor: effect on nasal absorption of human granulocyte colony-stimulating factor

Efficacy of SPM-NONOate following intrapulmonary delivery in promoting absorptions of poorly absorbed macromolecules in rats and the underling mechanism

This research aims to investigate the potential of N-[4-[1-(3-Aminopropyl)-2-hydroxy-2-nitrosohydrazino]butyl]-1,3-propanediamine (SPM-NONOate) for promoting the absorption of poorly absorbed macromolecules delivered by intrapulmonary route. Influence of SPM-NONOate on the drug absorption was characterized by using a series of fluorescein isothiocyanate-labeled dextrans (FDs) as affordable models of hydrophilic macromolecules with established tools for quantitative analysis. SPM-NONOate increased concentration-dependently within 1-10 mM the pulmonary absorptions of FDs in rats. Moreover, this promoting effect varied with the molecular weight of FDs, and the largest absorption enhancement effect was obtained for FD70. SPM-NONOate also showed promising enhancement potential on the absorption of some therapeutic peptides, where obvious hypoglycemic and hypocalcemic effects were observed after intrapulmonary delivery of insulin and calcitionin, respectively, with SPM-NONOate to rats. The safety of SPM-NONOate was confirmed based on measurement of some biological markers in bronchoalveolar lavage fluid (BALF) of rats. Additionally, mechanism underling the absorption enhancement action of SPM-NONOate was explored by combinatorial administration of FD4 and SPM-NONOate with various scavengers and generator to rat lungs. Results indicated that NO released from SPM-NONOate induced the enhancement in the drug absorption, and peroxynitrate, a NO metabolite, possibly participated in the absorption enhancing action of SPM-NONOate.

Excellent Absorption Enhancing Characteristics of NO Donors for Improving the Intestinal Absorption of Poorly Absorbable Compound Compared with Conventional Absorption Enhancers

The characteristics of NO donors, NOC5 [3-(2-hydroxy-1-(1-methylethyl-2-nitrosohydrazino)-1-propanamine), NOC12 [N-ethyl-2-(1-ethyl-2-hydroxy-2-nitrosohydrazino)-ethanamine] and SNAP [S-nitroso-N-acetyl-DL-penicillamine] as absorption enhancers for poorly absorbable drugs were examined in rats using an in situ closed loop method. They were compared with a group of conventional absorption enhancers including sodium glycocholate (NaGC), sodium caprate (NaCap), sodium salicylate (NaSal) and n-dodecyl-beta-D-maltopyranoside (LM). 5(6)-carboxyfluorescein (CF) was used as a model drug to investigate effectiveness, site-dependency, and concentration-dependency of the tested enhancers. Overall, the NO donors can improve the intestinal absorption of CF at low concentration (5 mM), whereas higher concentration was required for the conventional absorption enhancers to elicit the absorption enhancing effect. In the small intestine, SNAP was the most effective absorption enhancers, although its concentration (5 mM) was lower than the conventional absorption enhancers (20 mM). On the other hand, LM and NaCap as well as the three NO donors were effective to improve the colonic absorption of CF. In the regional difference in the absorption enhancing effects, the NO donors showed significant effects in all intestinal regions, whereas we observed a regional difference in the absorption enhancing effect of the other conventional absorption enhancers. In the conventional enhancers, the absorption enhancing effects were generally greater in the large intestine than those in the small intestine. LM and NaCap were ineffective in the jejunum, although they were effective for improving the absorption of CF in the colon. NaSal was ineffective in both the jejunum and the colon. The absorption enhancement produced by NO donors was greatly affected by increasing the enhancer concentration from 3 to 5 mM, but only a slight increase was obtained when the concentration was raised to 10 mM. Similar results were obtained for the other enhancers over the range of 10 to 20 mM, but the absorption enhancing effects of these enhancers were almost saturated above these concentrations. These results suggest that NO donors possess excellent effectiveness as absorption enhancers for poorly absorbable drugs compared with the conventional enhancers. They can enhance intestinal absorption of CF from all intestinal regions and they are effective at very low concentrations.

Nitric oxide donors can enhance the intestinal transport and absorption of insulin and [Asu1,7]-eel calcitonin in rats

The characteristics of three NO donors, 3-(2-hydroxy-1-(1-methylethyl)-2-nitrosohydrazino)-1-propanamine (NOC5), N-ethyl-2-(1-ethyl-2-hydroxy-2-nitrosohydrazino)-ethanamine (NOC12) and S-nitroso-N-acetyl-DL-penicillamine (SNAP) as absorption enhancers for peptide drugs were examined in rats using a modified Ussing chamber method and an in situ closed loop method. Insulin and [Asu(1,7)]-eel calcitonin (ECT) were used as a model drug to investigate the effectiveness of the tested enhancers. The NO donors significantly increased the in vitro permeability of insulin across all intestinal membranes. In general, the absorption enhancement effects of these NO donors were greater in the colon than those in the jejunum and ileum. Of these NO donors, SNAP was the most effective enhancer. Their effects were concentration-dependent over the range of 0.01 to 0.1 mM. However, 0.1 mM NO donors had almost the same effects as those at 1 mM concentration. The absorption-enhancing effects of the three NO donors were inhibited by the co-administration of 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazole-1-oxyl 3-oxide, sodium salt (carboxy-PTIO), an NO scavenger, suggesting that NO might be responsible for the efficacy of NO donors. In the in situ closed loop experiments, the three enhancers significantly improved the pharmacological availability % (PA%) of insulin in the small and large intestine. Similar results were also obtained when NO donors were added to ECT solution by an in situ closed loop method. These results suggest that NO donors possess excellent effectiveness for the use as absorption enhancers of peptide drugs and they are very effective at lower concentrations compared to the conventional enhancers.

Epinephrine is an enhancer of rat intestinal absorption

Some physiological substances, including acetylcholine and nitric oxide, are useful candidates for stimulation of intestinal absorption of drugs. In the present study, we elucidated the ability of epinephrine (Epi) to stimulate the intestinal absorption of drugs. We evaluated the ability of Epi to enhance absorption of macromolecules using dextran (Mw 4000 Da), which is poorly absorbed from the intestine, as a model compound in situ in a closed loop of the rat jejunum. Treatment of the jejunum with Epi resulted in significant increase in absorption of dextran in a dose-dependent fashion. The area under the curve (AUC) from 0 to 4 h in the Epi-treated jejunum was 13-fold higher than that in the vehicle-treated jejunum. The absorption-enhancing activity of Epi was 40-fold higher than that of caprate, a clinically used absorption-enhancer of drugs. In the experimental conditions used in this study, histological injury of the mucosa and perturbation of the mucosal membrane were not observed in the Epi-treated jejunum. Treatment with an antagonist of alpha-adrenergic receptors attenuated the stimulation of intestinal absorption by Epi, and treatment with an agonist of alpha-adrenergic receptors resulted in enhancement of intestinal absorption. While an antagonist of beta-adrenergic receptors enhanced the absorption-enhancing effect of Epi, an agonist of beta-adrenergic receptors stimulated intestinal absorption. These results indicate that stimulation of adrenergic receptors may be a novel strategy for intestinal absorption of drugs.

Absorption enhancers for nasal drug delivery

This paper describes the basic concepts for the transmucosal delivery of drugs, and in particular the use of the nasal route for delivery of challenging drugs such as polar low-molecular-weight drugs and peptides and proteins. Strategies for the exploitation of absorption enhancers for the improvement of nasal delivery are discussed, including consideration of mechanisms of action and the correlation between toxic effect and absorption enhancement. Selected enhancer systems, such as cyclodextrins, phospholipids, bioadhesive powder systems and chitosan, are discussed in detail. Examples of the use of these enhancers in preclinical and clinical studies are given. Methods for assessing irritancy and damage to the nasal membrane from the use of absorption enhancers are also described. Finally, the mucosal use of absorption enhancers (chitosan) for the improved nasal delivery of vaccines is reported with reference to recent phase I/II clinical studies.

Challenges for the oral delivery of macromolecules

The rapid integration of new technologies by the pharmaceutical industry has resulted in numerous breakthroughs in the discovery, development and manufacturing of pharmaceutical products. In particular, the commercial-scale production of high-purity recombinant proteins has resulted in important additions to treatment options for many large therapeutic areas. In addition to proteins, other macromolecules, such as the animal-derived mucopolysaccharide heparins, have also seen dramatic growth as injectable pharmaceutical products. To date, macromolecules have been limited as therapeutics by the fact that they cannot be orally delivered. This article will address the current status and future possibilities of oral macromolecular drug delivery.