Pharmaceutical Preformulation Testing

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Questions and Answers

What role do co-solvents play in the solubility of orally administered drugs?

They improve the aqueous solubility of the drug. (correct)

They increase the stability of acidic drugs.

They help drugs ionize in the gastrointestinal tract.

They decrease the drug's partition coefficient.

In terms of drug absorption, what is the significance of pKa?

It indicates the degree of non-ionization at physiological pH. (correct)

It determines the drug's water solubility.

It measures the stability of drugs in solution.

It defines the effectiveness of co-solvents.

What does hygroscopicity refer to?

The tendency of a solid to take up water from the atmosphere. (correct)

The ability of a drug to dissolve in lipid materials.

The concentration ratio of a drug in oil and aqueous phases.

The stability of a drug in aqueous solutions.

What does the partition coefficient represent?

The concentration of a drug in oil phase relative to aqueous phase. Signup and view all the answers

Which factor does NOT affect solid phase stability of drugs?

Hydrosolubility Signup and view all the answers

Why is the rotation disc method used in drug formulation?

To assess the dissolution rate of the drug. Signup and view all the answers

What is a major concern when formulating new drug substances?

Drug's compatibility with excipients. Signup and view all the answers

What characteristic must an orally administered drug have to ensure absorption?

It must dissolve in the aqueous fluid of the GIT. Signup and view all the answers

What is the primary purpose of preformulation testing in drug development?

To investigate physical and chemical properties of drug substances Signup and view all the answers

Which of the following is NOT a reason for performing preformulation testing?

To develop various polymorphic forms Signup and view all the answers

What defines polymorphism in a drug compound?

The ability to crystallize into various species with different structures Signup and view all the answers

How does particle size affect drug formulation?

It influences solubility and dissolution rate Signup and view all the answers

Which property primarily impacts the ability of a powder to be processed through tablet machines?

Flow properties of the powder Signup and view all the answers

What role does crystallinity play in bulk properties of a drug?

It describes the outer appearance and internal arrangement of crystals Signup and view all the answers

What is indicated by a relationship between particle size and surface area?

As particle size decreases, surface area increases Signup and view all the answers

Which factor can influence polymorphic transitions in a drug substance?

Rate of cooling during crystallization Signup and view all the answers

Study Notes

Preformulation Testing

First step in dosage form development
Investigates physical and chemical properties of drug substance alone and combined with excipients
Physiochemical properties determined by in vitro experiments

Importance of Preformulation

Prepare dosage forms with desired quality
Achieve high physiological availability and therapeutic qualities
Develop optimal dosage forms
Targeted drug delivery systems
Patient compliance
Minimize cost of finished product
Minimize errors in formulation

Bulk Properties

Crystallinity: Appearance and internal structure of crystals
Polymorphism: Ability of compounds to crystallize as different crystalline species with different internal structure
Particle size: Affects solubility, dissolution rate, and absorption
Powder flow property: Determines which excipients are needed for compressed dosage forms
Surface Characteristics: Hygroscopicity - tendency of solid to absorb water from the atmosphere

Solubility Analysis

Aqueous solubility: Orally administered drugs must dissolve in gastrointestinal fluids for absorption
Drug pKa/ Ionization at physiological pH: Non-ionized substances are lipid-soluble and transported passively by diffusion, ionized substances are lipid insoluble and have slow permeation
Partition coefficient: Concentration of drug in oil phase to concentration of drug in aqueous phase, important for membrane penetration

Dissolution

Important for gastrointestinal absorption
Determined by the rotating disc method

Stability Analysis

Solution phase stability: Effect of pH on stability, acid-sensitive drugs need protection from gastric acidity
Solid phase stability: Depends on temperature, pH, humidity, hydrolysis, and oxidation

Compatibility

Interaction of drugs with preservatives, stabilizers, dyes, and flavors
Formulators need to identify compatible excipients

Answers

Dissolution rate: Rotating disc method
Crystal habit: Outer appearance and internal structure
Hygroscopicity: Tendency of a solid to absorb water
Preformulation testing: The first step in the development of dosage forms
Partition coefficient: Concentration of drug in oil phase to concentration of drug in aqueous phase

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Description

Explore the critical first steps in drug development through preformulation testing. This quiz covers the importance of evaluating the physical and chemical properties of drug substances, as well as the effects of excipients on dosage forms. Understand how these assessments impact the development of effective and patient-compliant medications.