Pharmacokinetics: Physiological Model


PHYSIOLOGIC MODEL
o   Also called as Blood flow rate –limited models and perfusion rate limited models.
o   Physiological models describe the drug disposition in terms of realistic physiological parameters such as blood flow and tissue partition co-efficient.
o   The number of compartments to be included in the model depends upon the disposition characteristics of drug.
o   Organs such as bone that have no drug penetration are excluded.
o   Most physiologic models are based on the assumption that the drug movement within a body region is much more rapid than its rate of delivery to that region by the perfusion blood and, therefore the model is said to be perfusion rate limited. The assumption is however applicable to the highly membrane permeable drugs i.e. low molecular weight, poorly ionized and highly lipophilic drugs.
o   For, highly polar, ionized and charged drugs, the model is referred to as membrane permeation rate limited.


ADVANTAGES OF PHYSIOLOGIC MODELING:
·         Mathematical treatment is straightforward.
·         Data fitting is not required; drug concentration in various body regions can be depicted on the basis of organ or tissue volume, perfusion rate and experimentally determined tissue to plasma partition coefficient.
·         The influence of altered physiology or pathology on drug disposition can be easily predicted from changes in various pharmacokinetic parameters since the parameters correspond to actual physiologic and anatomic measures.
·         Correlation of data in several animal species is possible and with some drugs, can be extrapolated to humans.
The only disadvantage of these comprehensive models is obtaining experimental data, which is very exhaustive

Comments

Post a Comment

Popular posts from this blog

PLANT LAYOUT FOR CAPSULE MANUFACTURING DEPARTMENT & MANUFACTURING PROCESS

Image
PLANT LAYOUT  FOR CAPSULE MANUFACTURING DEPARTMENT: ENVIRONMENT CONDITION FOR CAPSULE FILLING AREA Humidity:          Not more than 35% RH Temperature:    Not more than 25% Area of each room, position of equipments, washing, drying, and sanitary facilities must be in accordance with GMP. MANUFACTURING PROCESS: CHEMCAPS Limited is an India based young and dynamic organization engaged in the manufacture and export of 'empty hard gelatin capsules' under the brand name of 'Chemlock' for discerning customers around the globe. COMPOSITION                                     Gelatin                                     Water                                     Colorants                                     Opecifier (TiO2 Dyes and Other)                                     Preservative MANUFACTURING OF HGC SHELL: SFR-901 FULLY AUTOMATIC CAPSULE MACHINE: FEATURES OF SFR-901 Ø   The Safrroys SFR-901 mod
Keep reading

ANTIOXIDANTS: In Pharmaceutical Formulation

Image
Introduction: Chemically they are reducing agents. They oxidize themselves and prevent oxidation of API. A substance that inhibits oxidation is called antioxidants. The effectiveness of antioxidant can depend on the concentration used and pH of solution. Examples:  Ascorbic acid,  butylated hydroxy anisole (BHA),  butylated hydroxyl toluene (BHT) Oxidation is a chemical reaction involving the loss of electrons or an increase in oxidation state. Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions. When the chain reaction occurs in a cell, it can cause damage or death to the cell. Antioxidants terminate these chain reactions by removing free radical intermediates, and inhibit other oxidation reactions. The following are some of the qualities of an ideal anti-oxidant: It should be readily soluble or dispersible in the medium. It should be effective in low concentration. It should be non-toxic. It should be non-irrita
Keep reading

3. Development of working hypothesis:

Image
After extensive literature survey, researcher should state in clear terms the working hypothesis or hypotheses. Working hypothesis is tentative assumption made in order to draw out and test its logical or empirical consequences. As such the manner in which research hypotheses are developed is particularly important since they provide the focal point for research. They also affect the manner in which tests must be conducted in the analysis of data and indirectly the quality of data which is required for the analysis. In most types of research, the development of working hypothesis plays an important role. Hypothesis should be very specific and limited to the piece of research in hand because it has to be tested. The role of the hypothesis is to guide the researcher by delimiting the area of research and to keep him on the right track. It sharpens his thinking and focuses attention on the more important facets of the problem. It also indicates the type of data required
Keep reading

Facebook Page

Knowledge of Pharma