Pharmaceutical Key Concepts Quiz

Design of Dosage Forms

• Dosage form design aims to achieve a predictable therapeutic response from a manufactured drug.
• Drug formulations are rarely pure; excipients are often used for pharmaceutical purposes.
• Excipients are often specialized and improve taste, flavor, dissolution and modify dissolution.
• Dosage form design needs to ensure chemical and physical stability, uniformity in dosage, and user acceptability.
• Patient-to-patient variation in bioavailability should be considered;
• Recent developments include drug delivery systems which are patient specific (e.g., respond to metabolic activity).
• Bioavailability is influenced by the rate and extent of absorption and the biological fate of drugs.
• Formulation factors can significantly impact drug performance, emphasizing the need for careful selection of the drug form.
• The chemical form of a drug substance is often a crucial factor in optimizing bioavailability.

Table 1.1: Dosage Forms Available for Different Administration Routes

• Lists various dosage forms for different administration routes (oral, rectal, topical, parenteral, respiratory, nasal, eye, ear).
• Examples include solutions, syrups, suspensions, emulsions, gels, powders, granules, capsules, tablets, suppositories, ointments, creams, pastes, lotions, gels, topical aerosols, foams, transdermal patches, injections, implants, irrigations, dialysis solutions, aerosols, inhalations, and various other forms.

Biopharmaceutical Aspects of Dosage Form Design

• Biopharmaceutics studies the relationship between the physical, chemical, and biological aspects of drugs and the biological response.
• Drug absorption is typically through passive diffusion or carrier-mediated transport.
• Factors influencing drug absorption include lipid solubility, ionization, and the drug's concentration gradient.
• Carrier-mediated transport mechanisms are essential in drug uptake.
• Drug absorption can lead to local or systemic therapeutic effects.

Oral Route

• Most common method for drug administration for systemic effects.
• Drugs are absorbed through the gastrointestinal tract.
• Onset of action is usually slower compared to other routes.
• Absorption can be influenced by interactions with materials present in the GI tract, gastric emptying time, and pH changes.
• Different types of oral dosage forms (tablets, capsules, suspensions, solutions) have varying rates of absorption.

Rectal Route

• Often used for local effect or for drugs inactivated or poorly absorbed by the oral route.
• Suppositories, solutions, creams, or gels administered rectally.
• Absorption can be irregular and difficult to predict.
• An advantage is that the drug bypasses the liver.

Parenteral Routes

• Involves injecting drugs via a needle.
• Preferred for rapid absorption (e.g., emergencies, unconscious patients).
• Subcutaneous, intramuscular, and intravenous injections are common types.
• Intravenous delivery is fastest and most predictable; subcutaneous is slower, and intramuscular falls in between.
• Injectable forms include solutions or suspensions in various vehicles.
• Depot preparations are designed for slow and sustained release.

Topical Route

• Applied directly to a body surface (skin, eyes, ears, etc.).
• Primarily intended for local effects.
• Commonly used for skin conditions, local infections or inflammation.
• Various topical forms for different applications: creams, ointments, pastes, solutions, etc.
• Percutaneous absorption is often poor and erratic.

Respiratory Route

• Drug delivery through inhalation.
• Aerosol mist, particles, or ultrafine solid particles.
• Suitable for asthma treatments and other specific conditions requiring rapid local effects.
• Preferred for drugs that need to be administered directly into the lungs.

Drug Factors in Dosage Form Design

• Includes properties impacting bioavailability (e.g., solubility, particle size, crystal form).
• Drug stability is crucial and depends on factors like light, moisture, heat and chemical interactions.
• Factors can lead to issues such as precipitation, decomposition, or modification of drug properties.

Therapeutic Considerations

• The clinical use, indications, and required duration of action for the drug
• Patient preferences in dosage form selection (solid, liquid)
• Considerations regarding various routes—oral, rectal, topical, parenteral, and respiratory.
• Factors like age/weight can influence preference for a particular dosage form.