Enhanced Bioavailability of Atorvastatin Calcium from Stabilized Gastric Resident Formulation.
Summary of "Enhanced Bioavailability of Atorvastatin Calcium from Stabilized Gastric Resident Formulation."
Oral bioavailability of atorvastatin calcium (ATC) is very low (only 14%) due to instability and incomplete intestinal absorption and/or extensive gut wall extraction. When ATC is packed in the form of tablets, powders, etc., it gets destabilized as it is exposed to the oxidative environment, which is usually present during the production process, the storage of the substance, and the pharmaceutical formulation. Therefore, stabilized gastro-retentive floating tablets of ATC were prepared to enhance bioavailability. Water sorption and viscosity measurement studies are performed to get the best polymer matrix for gastro-retention. A 3(2) factorial design used to prepare optimized formulation of ATC. The selected excipients such as docusate sodium enhanced the stability and solubility of ATC in gastric media and tablet dosage form. The best formulation (F4) consisting of hypromellose, sodium bicarbonate, polyethylene oxide, docusate sodium, mannitol, crosscarmellose sodium, and magnesium stearate, gave floating lag time of 56 ± 4.16 s and good matrix integrity with in vitro dissolution of 98.2% in 12 h. After stability studies, no significant change was observed in stability, solubility, floating lag time, total floating duration, matrix integrity, and sustained drug release rates, as confirmed by DSC and powder X-ray diffraction studies. In vivo pharmacokinetic study performed in rabbits revealed enhanced bioavailability of F4 floating tablets, about 1.6 times compared with that of the conventional tablet (Storvas® 80 mg tablet). These results suggest that the gastric resident formulation is a promising approach for the oral delivery of ATC for improving bioavailability.
Affiliation
Department of Pharmaceutics, Y. B. Chavan College of Pharmacy, Dr. Rafiq Zakaria Campus, Rauza Bagh, Aurangabad, 431001, MS, India, furkhankhan@rediffmail.com.
Journal Details
This article was published in the following journal.
Name: AAPS PharmSciTech
ISSN: 1530-9932
Pages:
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/21879394
- DOI: http://dx.doi.org/10.1208/s12249-011-9673-3
Medical and Biotech [MESH] Definitions
Gastric Dilatation
Abnormal distention of the STOMACH due to accumulation of gastric contents that may reach 10 to 15 liters. Gastric dilatation may be the result of GASTRIC OUTLET OBSTRUCTION; ILEUS; GASTROPARESIS; or denervation.
Vagotomy, Proximal Gastric
Vagal denervation of that part of the STOMACH lined with acid-secreting mucosa (GASTRIC MUCOSA) containing the GASTRIC PARIETAL CELLS. Since the procedure leaves the vagal branches to the antrum and PYLORUS intact, it circumvents gastric drainage required with truncal vagotomy techniques.
Parietal Cells, Gastric
Rounded or pyramidal cells of the GASTRIC GLANDS. They secrete HYDROCHLORIC ACID and produce gastric intrinsic factor, a glycoprotein that binds VITAMIN B12.
Calcium Signaling
Signal transduction mechanisms whereby calcium mobilization (from outside the cell or from intracellular storage pools) to the cytoplasm is triggered by external stimuli. Calcium signals are often seen to propagate as waves, oscillations, spikes, sparks, or puffs. The calcium acts as an intracellular messenger by activating calcium-responsive proteins.
Intracellular Calcium-sensing Proteins
Intracellular signaling peptides and proteins that bind to CALCIUM. They undergo allosteric changes when bound to CALCIUM that affects their interaction with other signal-transducing molecules. They differ from CALCIUM-SENSING RECEPTORS which sense extracellular calcium levels.
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