Lecture 25 - Drug delivery Flashcards
(30 cards)
Why do we take medicines?
To achieve a biological effect and must deliver effective drug concentration at site of action.
What is a Drug Delivery System?
A formulation or device that safely brings the therapeutic agent to a specific body site at a certain time and rate to achieve an effective concentration.
What are the types of natural products based on complexity?
- Whole botanical materials (powdered plants) * Native extracts (raw extracts) * Processed extracts (concentrated or purified) * Isolated chemical compounds (single molecules, e.g., curcumin)
What is the goal of preformulation considerations for natural products?
Optimize active substance into a medicine based on physicochemical properties.
What are the physicochemical properties considered in preformulation?
- Solubility * Molecular dissociation (pKa) * Partition coefficient (Log P) * Dissolution rate (in biological pH)
Define solubility in the context of drug formulation.
Max concentration of drug dissolved in a solvent.
What is dissolution?
The process of drug particles dissolving over time.
What must be true for a drug to be absorbed in the body?
The drug must be in solution.
What equation governs the dissolution rate?
dmdt=kA(Cs−C) where k = dissolution rate constant, A = surface area, Cs = solubility, C = concentration in solution.
What is the purpose of standardized dissolution apparatus (USP)?
To mimic in vivo conditions and predict in vivo drug performance.
What does the Biopharmaceutical Classification System (BCS) classify?
Solubility and permeability of drugs.
What are the four classes of the Biopharmaceutical Classification System (BCS)?
- Class I: High solubility, High permeability * Class II: Low solubility, High permeability * Class III: High solubility, Low permeability * Class IV: Low solubility, Low permeability
Why formulate drugs?
- Facilitate manufacturing and ensure quality * Improve stability * Enhance patient handling and compliance * Improve bioavailability
List the routes of administration mentioned.
- Parenteral (IM, IV, SC) * Oral * Pulmonary * Transdermal * Rectal * Ocular * Nasal
What is the most popular and convenient route of administration?
Oral route.
What are some barriers to the oral route of administration?
- pH variation in GI tract * Enzymatic degradation (proteases) * Physical barriers (membranes)
What are tablets?
Compressed powder discs and the most common oral dosage form.
What are the benefits of tablets?
- Easy manufacturing * Standardized dose * Patient-friendly
What challenges do herbal powders present for tablet formulation?
- Fine * Light * Poorly compressible * Hygroscopic * Poor flowability
What is the purpose of granulation in drug formulation?
To improve powder flow and compressibility.
What granulation technique is preferred for moisture-sensitive herbs?
Dry granulation (roller compaction).
What are two-piece capsules made of?
Cap and body, traditionally gelatin, now also vegetarian alternatives.
What are emulsions?
Stable dispersions of oil & water phases that improve bioavailability of lipophilic compounds.
