Practicum 2: Study for Determining the Partition Coefficient

University:
The University of Tennessee at Martin
Course:
PHCY 1213 | Pharmacy Law I
Academic year:

2024
Views:

260

Pages:

2
Author:

Nicho H.

PRACTICUM 2: STUDY FOR DETERMINING THE PARTITION COEFFICIENT OF MATERIALS ACTIVE PHARMACY Description of Theory A drug compound must be able to penetrate biological membranes and reach target tissues in sufficient quantities to provide activity. The physicochemical property parameters that play the most role in the distribution process are lipophilic parameters. Parameters of lipophilic properties Often used in quantitative relationships of activity structures, one of them is the logarithm of the partition coefficient (log P). The partition coefficient is the ratio of drug levels in lipids and drug levels in water after equilibrium occurs. Or it could also be the solubility of the drug in lipids divided by the solubility of the drug in water. The partition coefficient influences the dissolution and permeation processes of a drug. In general, the greater the partition coefficient of a drug, the more difficult it is to dissolve in water, so dissolution will be slow, conversely, the smaller the partition coefficient, the more difficult it will be to dissolve in lipids, so permeation will be slow. The partition coefficient (P) can be calculated using the following equation: P = Co / Cw Where, Co=drug content in oil (non-polar solvent) Cw= drug levels in water (polar solvent) In general, medicines are weak acids or weak acids. If the drug is dissolved in water, some of it will ionize. The size of the ionized drug fraction depends on the pH of the solution. Nonionizing drugs (unionized) is more easily soluble in lipids, whereas in ionic form the solubility is small or even practically insoluble, thus the influence of pH on the rate of absorption of drugs that are weak acids or weak bases is very large. If there is no interaction between the substance and the solvent, then: Co = Cm - Cw Where, Cm=initial substance content For ionized compounds, the effect of degree ionization (α) should not be ignored. P = Co / Cw (1-α) The P value of compounds varies greatly over very large distances, to facilitate calculations it is usually used in logarithmic form (log P) log P = log Co / log Cw Implementation of Practicum a. Tools and materials Equipment: Separating funnel, UV-Vis spectrophotometry, analytical balance, Erlenmeyer flask Material:Ketoprofen, chloroform, distilled water b. Work procedures : 1) Determination of the maximum wavelength and creation of a ketoprofen calibration curve. 2) The test solution is made by dissolving 100 mg of ketoprofen using 50 mL of chloroform until completely dissolved in an Erlenmeyer flask. Put it into the separating funnel. 3) Add 50 mL of water, shake for 5 minutes. Then let it sit for 10 – 15 minutes until the two liquids separate from each other. 4) Separate the top layer from the bottom layer, then measure the absorbance of the chloroform layer using UV-Vis spectrophotometry at the maximum wavelength. Calculate the ketoprofen concentration in each layer using the linear regression equation obtained from creating a calibration curve.