Lipid dosage forms

Lipid-Lowering Drug Dosage Forms Usual Adult Maintenance Dose Range Adverse Effects... 

In recent years, parenteral dosage forms, especially IV forms, have enjoyed increased use. The reasons for this growth are many and varied, but they can be summed up as (a) new and better parenteral administration techniques, (b) an increasing number of drugs that can be administered only by a parenteral route, (c) the need for simultaneous administration of multiple drugs in hospitalized patients receiving IV therapy, (d) new forms of nutritional therapy, such as intravenous lipids, amino acids, and trace metals, and (e) the extension of parenteral therapy into the home. 

In this book we will focus on physicochemical profiling in support of improved prediction methods for absorption, the A in ADME. Metabolism and other components of ADME will be beyond the scope of this book. Furthermore, we will focus on properties related to passive absorption, and not directly consider active transport mechanisms. The most important physicochemical parameters associated with passive absorption are acid-base character (which determines the charge state of a molecule in a solution of a particular pH), lipophilicity (which determines distribution of a molecule between the aqueous and the lipid environments), solubility (which limits the concentration that a dosage form of a molecule can present to the solution and the rate at which the molecule dissolves from... 

The Sartorius Absorption Model (26), which served as the forerunner to the BCS, simulates concomitant release from the dosage form in the GI tract and absorption of the drug through the lipid barrier. The most important features of Sartorius Absorption Model are the two reservoirs for holding different media at 37°C, a diffusion cell with an artificial lipid barrier of known surface area, and a connecting peristaltic pump which aids the transport of the solution or the media from the reservoir to the compartment of the diffusion cell. The set-up is shown in Figures 7a and b. 

The crystalline nature of these lipids provides challenges in the manufacture of certain types of food products. To address successfully these sometimes conflicting and demanding objectives, it is clear that specific encapsulation processes must be designed to formulate pure bioactive substances into their appropriate dosage forms and also to improve their overall efficacy and safety (Augustin and Hemar, 2009 McClements et al, 2008, 2009). 

Final Dosage Forms of Lipid-Based Drug Delivery Systems. 245... 

Use of these semisolid and solid approaches can potentially alleviate the chemical stability problems sometimes observed for liquid-Llled formulations, and may eventually offer the possibility of development of a tablet dosage form using conventional equipment. Liquid lipid-based formulations, however, generally afford the greatest enhancement of bioavailability for water-insoluble drugs, as well as affording more rapid development for First-in-Human studies. Any decisions on the best formulation route would have to be evaluated on a case-by-case basis. 

Cannon, J. (2005) Oral solid dosage forms of lipid-based drug delivery systemSharm. Rey8 108-113. 

Carrigan, P.J. and Bates, T.R. (1973) Biopharmaceutics of drugs administered in lipid containing dosage forms. I. Gl absorption of griseofulvinfrom an oil-in-water emulsion inthedaPharm. Sci., 62 1476-1479. 

N. A. Armstrong and K. C. James, Drug release from lipid based dosage forms. Part 2, Int. J. Pharmaceut. 6 195-204 (1980). 

S. Chakrabarti and F. M. Belpaire, Bioavailability of phenytoin in lipid containing dosage forms in rats, J. Pharm. Pharmac. 30 330-331 (1978). 

Y. Yamahira, T. Noguchi, H. Takenaka and T. Maeda, Biopharmaceutical studies of lipid containing oral dosage forms relationship between drug absorption rate and digestibility of vehicles, Int. J. Pharmaceut. 3 23-31 (1979). 

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