In vitro-in vivo evaluation of a controlled release buccal bioadhesive device for oral drug delivery

The passive diffusion improvement of Vitamin B12 intestinal absorption by Gelucire that fit for commercialized production

Vitamin B₁₂ (VB₁₂) is a vital micronutrient to maintain the normal state of the hematopoietic system. It must be obtained from the diet since the human body cannot synthesize it. Moreover, the absorption of VB₁₂ needs to be mediated by intrinsic factor on the gastrointestinal (GI) track. The abnormalities in the stomach or lack of such intrinsic factors may result in poor oral absorption of VB₁₂. However, the very advanced formulation strategies were generally very costly and still in the development stage. Thus, the objectives of the present study were to increase the VB₁₂ intestinal absorption by conventional excipients of Gelucire 44/14 (G44/14) or Labrasol, which could be potentially formulated as a cost effect balanced product. The in vitro Caco-2 cell model was applied for the absorption study. A novel VB₁₂ solid dispersion was subsequently prepared and further characterized by Differential scanning calorimetry, Fourier transform infrared spectroscopy, and Scanning electron microscopy, respectively. The membrane permeability of the VB₁₂ solid dispersion was finally evaluated using ex vivo rat everted gut sac method. The results suggested that G44/14 could significantly enhance the intestinal absorption of VB₁₂ via P-glycoprotein inhibition in vitro (P < 0.01). The membrane permeability of VB₁₂could be significantly (P < 0.01) improved by G44/14-VB₁₂ solid dispersion at a proportion of carrier: drug ratio of 20:1.The liquidfied solid dispersion was finally directly filled in the hard gelatin capsules. In conclusion, the cheap and simplified process of VB₁₂ complex prepared by G44/14 could potentially increase VB₁₂ intestinal absorption, which may be liable to commercial manufacturing.

Methods to assess vitamin B12 bioavailability and technologies to enhance its absorption

Vitamin B12 (B-12) deficiency is still relatively common in low-, medium-, and high-income countries, mainly because of dietary inadequacy and, to a lesser extent, malabsorption. This narrative review is based on a systematic search of evidence on methods to assess B-12 bioavailability and technologies to enhance its absorption. A total of 2523 scientific articles identified in PubMed and 1572 patents identified in Orbit Intelligence were prescreened. Among the reviewed methods, Schilling's test and/or its food-based version (using cobalamin-labeled egg yolk) were used for decades but have been discontinued, largely because they required radioactive cobalt. The qualitative CobaSorb test, based on changes in circulating holo-transcobalamin before and after B-12 administration, and the 14C-labeled B-12 test for quantitative measurement of absorption of a low-dose radioactive tracer are currently the best available methods. Various forms of B-12 co-formulated with chemical enhancers (ie, salcaprozate sodium, 8-amino caprylate) or supplied via biotechnological methods (ie, microbiological techniques, plant cells expressing cobalamin binding proteins), encapsulation techniques (ie, emulsions, use of chitosan particles), and alternative routes of administration (ie, intranasal, transdermal administration) were identified as potential technologies to enhance B-12 absorption in humans. However, in most cases the evidence of absorption enhancement is limited.

Vitamin B12-Loaded Buccoadhesive Films as a Noninvasive Supplement in Vitamin B12 Deficiency: In Vitro Evaluation and In Vivo Comparative Study With Intramuscular Injection

This study aimed to formulate and evaluate vitamin B12-loaded buccal mucoadhesive hydrogel films. Various film formulations were prepared using chitosan and polyvinyl alcohol. The prepared films were characterized for thickness, weight variation, drug content, percentage moisture uptake and moisture content, surface pH, mechanical properties, in vitro release, and mucoadhesion. Vitamin B12 bioavailability from the optimized formulation was studied on rabbits by the aid of enzyme-linked immunosorbent assay. Neuroton^® I.M. injection was used for comparison. The films had acceptable mechanical and mucoadhesion properties. The percentages of moisture content of the optimized formulation were 3.2 ± 0.95, whereas the percentage drug released was 98.59 ± 1.41% at the end of 40 min. FTIR revealed the incidence of drug/polymer interaction. Differential scanning calorimetry revealed the possibility of the dispersion of cyanocobalamin in a molecular state with complete amorphization in the polymers. The estimated AUC_0-8h showed 1.5-fold increases in the bioavailability of cyanocobalamin from the optimized formulation compared with the marketed I.M. injection. These findings warrant that vitamin B12 buccal film formulation can be considered as an effective alternative portal with noninvasive and more convenient characteristics compared with the I.M. injection dosage form.

Polymers for mucoadhesive drug delivery system: a current status

To overcome the relatively short gastrointestinal (GI) time and improve localization for oral controlled or sustained release drug delivery systems, bioadhesive polymers that adhere to the mucin/epithelial surface are effective and lead to significant improvement in oral drug delivery. Improvements are also expected for other mucus-covered sites of drug administration. Bioadhesive polymers find application in the eye, nose, and vaginal cavity as well as in the GI tract, including the buccal cavity and rectum. This article lays emphasis mainly on mucoadhesive polymers, their properties, and their applications in buccal, ocular, nasal, and vaginal drug delivery systems with its evaluation methods.

Oral Bioadhesive Drug Delivery Systems

The oral mucosal cavity is a feasible, safe, and very attractive site for drug delivery with good acceptance by users. The mucosa is relatively permeable and robust, shows short recovery times after stress or damage, is tolerant to potential allergens, and has a rich blood supply. Moreover, oral mucosal drug delivery bypasses the first-pass effect and avoids presystemic elimination in the gastrointestinal tract. Bioadhesive systems provide intimate contact between a dosage form and the absorbing tissue, which may result in high concentration in a local area and hence high drug flux through the absorbing tissue. The efficacy of oral bioadhesive drug delivery systems is affected by the biological environment and the properties of the polymer and the drug. In the present paper, we review systematically some relevant citations regarding the environment, strategies for oral drug delivery and evaluation, and utilization of the main polymers.

Spray-dried Amioca® starch/Carbopol® 974P mixtures as buccal bioadhesive carriers

In the present study, spray-dried Amioca starch/Carbopol 974P mixtures were evaluated as potential buccal bioadhesive tablets. Carbopol (C 974P) concentrations from 5 to 75% were tested. All spray-dried mixtures showed a comparable or better bioadhesive capacity compared to a reference formulation (DDWM/C 974P 95/5). The bioadhesive capacities of Amioca/Carbopol 974P mixtures were improved by spray-drying. All spray-dried mixtures showed significantly higher work of adhesion values compared to their equivalent physical mixtures. The influence of Carbopol concentration on the in vivo adhesion time of placebo tablets and in vitro miconazole nitrate release was tested. The ratio Amioca/C 974P 70/30 showed the longest in vivo adhesion time (24.5+/-8.5 h). Lower and higher C 974P concentrations had a shorter in vivo adhesion time. The mixtures containing between 15 and 30% C 974P could all sustain the in vitro miconazole nitrate release over 20 h. Again, lower and higher C 974P concentrations showed a faster in vitro miconazole release. The drug loading capacity of a spray-dried mixture containing 20% C 974P was investigated in vivo in dogs using testosterone as model drug. The spray-dried mixture could be loaded with 60% drug without loosing its in vivo bioadhesive and pharmacokinetic properties.

Buccal drug delivery

Buccal formulations have been developed to allow prolonged localised therapy and enhanced systemic delivery. The buccal mucosa, however, while avoiding first-pass effects, is a formidable barrier to drug absorption, especially for biopharmaceutical products (proteins and oligonucleotides) arising from the recent advances in genomics and proteomics. The buccal route is typically used for extended drug delivery, so formulations that can be attached to the buccal mucosa are favoured. The bioadhesive polymers used in buccal drug delivery to retain a formulation are typically hydrophilic macro-molecules containing numerous hydrogen bonding groups. Newer second-generation bioadhesives have been developed and these include modified or new polymers that allow enhanced adhesion and/or drug delivery, in addition to site-specific ligands such as lectins. Over the last 20 years a wide range of formulations has been developed for buccal drug delivery (tablet, patch, liquids and semisolids) but comparatively few have found their way onto the market. Currently, this route is restricted to the delivery of a limited number of small lipophilic molecules that readily cross the buccal mucosa. However, this route could become a significant means for the delivery of a range of active agents in the coming years, if the barriers to buccal drug delivery are overcome. In particular, patient acceptability and the successful systemic delivery of large molecules (proteins, oligonucleotides and polysaccharides) via this route remains both a significant opportunity and challenge, and new/improved technologies may be required to address these.