Pertemuan 3 kelarutan dan fenomena distribusi

Introduction

This tutorial focuses on the principles of solubility and distribution phenomena, essential knowledge for pharmacists when preparing solutions or liquids. Understanding solubility helps in selecting appropriate mediums for dissolving drug combinations, preventing degradation, and ensuring effective therapeutic effects within the human body.

Step 1: Understand Solubility Concepts

• Definition of Solubility: The ability of a substance (solute) to dissolve in a solvent to form a solution.
• Factors Affecting Solubility:
  • Temperature: Higher temperatures often increase solubility.
  • Pressure: Mainly affects gases; higher pressure increases gas solubility.
  • Nature of Solute and Solvent: Polar solutes dissolve better in polar solvents (like water), while non-polar solutes dissolve in non-polar solvents (like oils).

Practical Tip

• Experiment with different temperatures and solvents to observe changes in solubility, helping to understand how different substances interact.

Step 2: Apply the Knowledge of Partition Coefficient

• Understanding Partition Coefficient: This is a ratio that describes how a substance distributes itself between two immiscible solvents, often water and oil.
• Importance in Pharmacology: Affects how drugs are absorbed, distributed, and eliminated in the body.
• Calculation:
  • Use the formula: [ \text{Partition Coefficient (P)} = \frac{[Drug]{oil}}{[Drug]{water}} ]
  • A higher coefficient indicates better lipid solubility, which can enhance drug absorption.

Common Pitfall to Avoid

• Do not overlook the impact of pH on the solubility and distribution of drugs; certain drugs may ionize in different pH environments, affecting their absorption.

Step 3: Select Appropriate Medium for Drug Preparation

• Choosing a Solvent: Based on the solubility and partition coefficient, select a solvent that will effectively dissolve the active ingredients.
• Considerations:
  • Stability of the drug in the chosen solvent.
  • Compatibility of the solvent with other ingredients in the formulation.
  • Regulatory guidelines regarding solvent use in pharmaceuticals.

Practical Application

• Conduct stability tests with various solvents and concentrations to identify the best formulation for your specific drug combination.

Step 4: Assess Distribution and Absorption in the Body

• Distribution: Understand how drugs travel through the bloodstream to reach their target organs.
• Factors Influencing Distribution:
  • Blood flow to the organ.
  • Binding to plasma proteins.
  • Tissue permeability.

Therapeutic Effects

• Calculate the expected therapeutic effect based on the drug's distribution profile, ensuring it reaches the target site in effective concentrations.

Conclusion

Understanding solubility and distribution phenomena is crucial for pharmacists in drug formulation. By mastering these concepts, you can optimize drug preparations, ensuring they are effective and safe for patient use. Next steps include experimenting with different formulations to gain hands-on experience and deepen your understanding of these principles in practice.