Drug Delivery Systems and Formulation Design

Definition: Methods or technologies used to deliver a pharmaceutical compound to achieve a therapeutic effect.
Types:
- Oral Delivery: Tablets, capsules, solutions.
- Parenteral Delivery: Injections, infusions.
- Topical Delivery: Creams, gels, transdermal patches.
- Inhalation: Aerosols, dry powders.
Key Concepts:
- Targeted Delivery: Focused delivery to specific tissues or cells.
- Controlled Release: Gradual release of drugs over time to maintain therapeutic levels.

Objectives: Create stable, effective, and safe drug products.
Factors Considered:
- Active Ingredients: Type and concentration.
- Excipients: Inactive substances that aid in formulation (binders, fillers, preservatives).
- Stability: Chemical and physical stability of the formulation over time.
- Compatibility: Interaction between active ingredients and excipients.
Methods:
- Pre-formulation Studies: Analyze properties of the drug and excipients.
- Formulation Development: Trial and error to optimize product characteristics.

Definition: Study of the absorption, distribution, metabolism, and excretion (ADME) of drugs.
Key Phases:
- Absorption: How a drug enters the bloodstream.
- Distribution: How the drug disperses throughout the body tissues.
- Metabolism: Biochemical modification of the drug, often in the liver.
- Excretion: Removal of the drug from the body (often through urine or feces).
Parameters:
- Half-life: Time taken for the drug concentration to reduce by half.
- Bioavailability: Fraction of the administered drug that reaches systemic circulation.

Definition: The physical form of a dose of medication, which affects its delivery and efficacy.
Types:
- Solid: Tablets, capsules, powders.
- Liquid: Solutions, suspensions, emulsions.
- Semisolid: Ointments, creams, gels.
- Gas: Inhalation aerosols.
Considerations in Design:
- Release Mechanism: Immediate vs. sustained release.
- Patient Compliance: Ease of use and administration.
- Therapeutic Index: The safety margin between the effective and toxic dose.

Definition: Study of the relationship between the physicochemical properties of drugs and their biological effects.
Key Aspects:
- Drug Solubility: Affects absorption and bioavailability.
- Permeability: Ability of the drug to cross biological membranes.
- Formulation Impact: How different formulations can alter pharmacokinetic behavior.
Importance:
- Drug Development: Helps optimize formulations for better therapeutic outcomes.
- Regulatory Considerations: Must meet guidelines for approval based on biopharmaceutical properties.

Definition: Techniques designed to transport pharmaceutical compounds to achieve specific therapeutic outcomes.
Types:
- Oral Delivery: Includes various forms like tablets, capsules, and solutions for systemic effects.
- Parenteral Delivery: Involves injections and infusions for bypassing the digestive system.
- Topical Delivery: Applies formulations like creams and gels directly onto the skin; transdermal patches allow absorption into the bloodstream.
- Inhalation: Utilizes aerosols and dry powders for targeting the respiratory system.
Key Concepts:
- Targeted Delivery: Delivers drugs specifically to desired tissues or cells to enhance efficacy and minimize side effects.
- Controlled Release: Ensures drugs are released steadily over time, maintaining therapeutic concentrations.

Objectives: Focuses on producing drug products that are stable, effective, and safe for patients.
Factors Considered:
- Active Ingredients: Type and concentration directly influence the drug's effect.
- Excipients: Inactive substances that support formulation, including binders, fillers, and preservatives.
- Stability: Assesses both chemical and physical stability of the formulation over its intended shelf life.
- Compatibility: Evaluates interactions between active ingredients and excipients to ensure formulation integrity.
Methods:
- Pre-formulation Studies: Analyzes the properties of drugs and excipients to inform formulation decisions.
- Formulation Development: Involves iterative testing to optimize formulation characteristics and performance.

Definition: Explores the ADME (Absorption, Distribution, Metabolism, Excretion) processes of drugs in the body.
Key Phases:
- Absorption: Mechanisms through which a drug enters the bloodstream from the site of administration.
- Distribution: Describes how the drug spreads throughout the body, affecting its concentration in various tissues.
- Metabolism: Refers to chemical transformations of the drug, typically occurring in the liver, impacting effectiveness and elimination.
- Excretion: The process of removing the drug from the body, predominantly through urine or feces.
Parameters:
- Half-life: Indicates the duration required for the drug concentration in the bloodstream to decrease by half, reflecting elimination speed.
- Bioavailability: Represents the proportion of the drug that enters the systemic circulation and is available for therapeutic action.

Definition: Refers to the specific form in which medication is administered, influencing delivery and therapeutic effect.
Types:
- Solid: Includes tablets, capsules, and powders for various therapeutic needs.
- Liquid: Composed of solutions, suspensions, and emulsions for patient-specific delivery.
- Semisolid: Formulations like ointments, creams, and gels for localized or systemic effects.
- Gas: Inhalation aerosols offering rapid onset of action in respiratory applications.
Considerations in Design:
- Release Mechanism: Differentiates between immediate release for quick effect and sustained release for prolonged action.
- Patient Compliance: Addresses ease of use and administration to enhance adherence to treatment.
- Therapeutic Index: Vital measure indicating the safety margin between effective and toxic doses.

Definition: Examines how the physicochemical properties of drugs correlate with their biological activity and therapeutic potential.
Key Aspects:
- Drug Solubility: Essential for proper absorption and achieving adequate bioavailability.
- Permeability: Levels of drug penetration through biological membranes determine efficacy.
- Formulation Impact: Variations in formulations can significantly modify pharmacokinetic behavior and therapeutic outcomes.
Importance:
- Drug Development: Critical for optimizing formulations to enhance therapeutic effectiveness and minimize adverse effects.
- Regulatory Considerations: Compliance with guidelines is necessary for drug approval based on biopharmaceutical properties.