Introduction to Pharmaceutics
Introduction
Pharmaceutics is the discipline of pharmacy that deals with the process of turning a new chemical entity (NCE) or pure drug into a medication that can be used safely and effectively by patients. It is also called the science of dosage form design.
Core Areas of Pharmaceutics
- Physical Pharmaceutics: Understanding basic physical chemistry necessary for dosage form design.
- Biopharmaceutics: Studying how drugs arrive at their site of action following administration.
- Dosage Form Design: The actual formulation and design of medicines.
- Pharmaceutical Microbiology: Avoiding or eliminating microorganisms in medicines (sterilization).
- Product Testing: Evaluating physical testing, drug release, and stability.
Drugs vs. Medicines
A Drug (or Active Pharmaceutical Ingredient - API) is the pharmacologically active ingredient. However, drugs are rarely administered alone. They require additives termed Excipients to make them into Medicines (Dosage Forms).
Medicines act as drug-delivery systems, ensuring the drug is administered in a safe, effective, accurate, and convenient manner.
Dosage Form Design Considerations
There are three major considerations in the design of dosage forms:
- Physicochemical Properties: The physical and chemical characteristics of the drug itself (solubility, particle size, etc.).
- Biopharmaceutical Considerations: How the route of administration (oral, injection, etc.) affects the rate and extent of drug absorption into the body.
- Therapeutic Considerations: The disease state being treated and the specific needs of the patient (e.g., age, difficulty swallowing).
Routes of Administration
Dosage forms are designed differently depending on how they enter the body:
- Oral: Tablets, capsules, liquids (most common).
- Parenteral: Injections and infusions (intravenous, intramuscular).
- Topical/Transdermal: Creams, gels, patches for skin application.
- Pulmonary: Aerosols and inhalers.
- Others: Nasal, ocular (eye), rectal, and vaginal routes.
Microbiology and Stability
A crucial part of pharmaceutics is ensuring that the medicine remains stable and free from contamination. This involves:
- Sterilization: Eliminating viable microorganisms, especially for injections and eye drops.
- Preservation: Adding antimicrobial preservatives to prevent growth during storage and use.
- Stability Testing: Ensuring the product has a safe shelf-life and that the drug does not degrade chemically.
- Packaging: Using appropriate containers to protect the medicine from light, moisture, and contamination.
The Goal of Formulation
Good formulation enhances therapeutic efficacy and limits adverse effects. For example, a modified-release capsule can reduce the frequency of dosing from three times a day to once daily, increasing patient convenience and compliance.
