Ceutics 1 exam

What is drug degradation?

Chemical or physical changes that decrease the quality, stability, potency, or performance of a drug product.

What is hydrolysis in drug degradation?

The breaking of a chemical bond by reaction with water, commonly affecting ester-containing drugs.

What is oxidation in the context of drug stability?

The loss of electrons, often involving a reaction with oxygen, which can lead to degradation of certain drugs.

What causes photolysis?

Chemical degradation caused by light, affecting light-sensitive drugs.

Define isomerization in drug degradation.

The conversion of a drug into another stereoisomer or geometric isomer.

What is a zero-order reaction?

A reaction where the rate is independent of drug concentration, resulting in a constant amount lost per unit time.

What characterizes a first-order reaction?

The rate depends on drug concentration, resulting in a constant percentage or fraction lost per unit time.

What is the most common cause of drug degradation?

Hydrolysis, particularly for drugs containing hydrolyzable functional groups like esters, amides, and lactams.

How can hydrolysis be prevented?

By controlling moisture, using appropriate packaging, and formulating as a dry dosage form.

What is photodegradation?

Decomposition of drugs caused by light exposure, which can be prevented using amber-colored or opaque packaging.

What strategies can reduce oxidation in drugs?

Reduce oxygen exposure, add antioxidants, use chelating agents, control pH, protect from light, and control temperature.

What are common physical changes in drug products?

Precipitation, color change, turbidity, sedimentation, caking, and changes in particle size.

Define generic name in pharmaceuticals.

The nonproprietary name of the active drug, such as acetaminophen.

What is a generic product?

A drug product marketed under its established/generic name rather than a brand name.

Differentiate between pharmaceutical equivalent and bioequivalent.

Pharmaceutical equivalents have the same active ingredient and dosage form, while bioequivalents have similar rates and extents of absorption.

What is a therapeutic equivalent?

A product that meets the requirements for pharmaceutical and bioequivalence and is expected to have the same clinical effect.

What is the rate equation for a zero-order reaction?

Rate = k, where the rate is constant and independent of concentration.

What is the integrated equation for a first-order reaction?

ln C = ln C₀ - kt, where the concentration decreases exponentially over time.

How does half-life differ between zero-order and first-order reactions?

In zero-order, half-life depends on initial concentration; in first-order, it is constant and does not depend on concentration.

What is the linear plot for zero-order reactions?

A plot of concentration (C) vs time (t) shows a straight line.

What is the linear plot for first-order reactions?

A plot of ln C vs time (t) shows a straight line.

What are the units of k in a first-order reaction?

1/time, indicating the rate constant's dependence on time.

What is the significance of controlling temperature in drug stability?

Higher temperatures generally accelerate chemical reactions, increasing the risk of degradation.

What is the role of antioxidants in drug formulation?

Antioxidants react preferentially with oxidizing species to prevent oxidation of the drug.

What are the consequences of physical instability in drug products?

Physical instability can lead to unacceptable changes like precipitation, turbidity, and sedimentation, even if the drug itself is stable.

What are some examples of physical instability in solutions?

Precipitation, color change, and turbidity.

What is the importance of using proper excipients in drug formulations?

They help maintain stability and prevent physical changes in the drug product.

How can light exposure affect drug stability?

Light can initiate chemical reactions that lead to degradation, necessitating protective packaging.

What is the rate equation for a first-order reaction?

Rate = kC

Does the rate of a zero-order reaction depend on concentration?

No

Does the rate of a first-order reaction depend on concentration?

Yes

What are the units of k for a zero-order reaction?

Concentration/time

What is the integrated rate equation for a first-order reaction?

ln C = ln C₀ - kt

What is the half-life formula for a first-order reaction?

t1/2 = 0.693/k

What type of plot is used to determine the order of a reaction?

C vs t for zero-order and ln C vs t for first-order

What is the purpose of stability studies?

To determine how a drug product changes over time under different conditions.

What is long-term stability testing?

Drug stored under normal conditions for an extended period to evaluate shelf life.

What is accelerated stability testing?

Drug exposed to stressful conditions to predict stability and identify potential degradation.

What is the Arrhenius equation?

k = Ae^(-Ea/RT)

What happens to reaction rate as temperature increases?

Reaction rate increases.

Define solubility.

The maximum amount of solute that can dissolve in a solvent under specified conditions.

Define dissolution.

The process by which a solid drug goes into solution.

Define diffusion.

Movement of molecules from an area of higher concentration to lower concentration.

What is the relationship between temperature and solubility for many solids?

As temperature increases, solubility generally increases.

How does pH affect the solubility of weak acids?

Increasing pH increases the solubility of weak acids.

What is the effect of salt formation on drug solubility?

It can improve ionization and solubility.

What is solid dispersion?

Dispersing a drug in a carrier to improve dissolution and reduce crystallinity.

What is complexation in drug solubility?

When a drug forms a complex with another molecule to improve solubility.

What is the general relationship for the solubility of weak bases as pH decreases?

Solubility of weak bases increases.

What is surface tension?

The tendency of a liquid surface to resist expansion, behaving like an elastic 'skin.'

What causes surface tension in liquids?

Unbalanced intermolecular forces experienced by surface molecules.

What is the significance of particle size in drug dissolution?

Reducing particle size increases surface area and can increase the rate of dissolution.

What is the role of surfactants in solubility?

Surfactants can increase apparent solubility through micellar solubilization.

What is the effect of polymorphism on drug properties?

Different crystal forms can have different solubilities, melting points, and dissolution rates.

What effect does surface tension have on wetting?

Surface tension affects wetting, spreading, dissolution, emulsion formation, and suspension formulation.

What is the primary function of surfactants?

Surfactants generally decrease surface tension, improving wetting of hydrophobic drug particles.

What does a small contact angle indicate?

A small contact angle (θ→0°) indicates good wetting, meaning the liquid spreads across the surface.

What does a large contact angle indicate?

A large contact angle (θ→180°) indicates poor wetting, meaning the liquid tends to form a bead.

What is the relationship between contact angle and wetting?

Smaller contact angle = better wetting; larger contact angle = poorer wetting.

What does a drug powder with a large contact angle with water indicate?

It indicates poor wetting and a hydrophobic surface.

What can improve the wetting of a hydrophobic surface?

A surfactant can improve wetting.

What is the difference between adsorption and absorption?

Adsorption is when molecules accumulate on the surface; absorption is when molecules enter the bulk/interior of a material.

What is physisorption?

Physisorption is a type of physical adsorption where molecules are held to the surface by weak intermolecular forces.

What are the characteristics of physisorption?

Physisorption is relatively weak, usually reversible, can form multiple layers, and has lower heat of adsorption.

What is chemisorption?

Chemisorption is a type of chemical adsorption where the adsorbate forms a stronger chemical bond with the surface.

What are the characteristics of chemisorption?

Chemisorption involves stronger interactions, is often more specific, difficult to reverse, and usually forms a monolayer.

What is the energy comparison between physisorption and chemisorption?

Physisorption has lower energy, while chemisorption has higher energy.

What happens to reaction rate when temperature increases?

Generally, the reaction rate increases because the rate constant k increases.

What is the difference between zero-order and first-order kinetics?

Zero-order kinetics have a rate independent of concentration, while first-order kinetics have a rate dependent on concentration.

What is the half-life formula for first-order kinetics?

The half-life for first-order kinetics is t1/2 = 0.693/k.

How does pH affect the solubility of weak bases?

For weak bases, decreasing pH leads to increased ionization and increased solubility.

What is hydrolysis in the context of drug degradation?

Hydrolysis is degradation involving water.

What is oxidation in drug degradation?

Oxidation is the loss of electrons; it can be reduced with antioxidants, oxygen control, and chelators.

What is photolysis?

Photolysis is degradation caused by light.

What does the term 'solubility' refer to?

Solubility refers to how much of a substance can dissolve in a solvent.

What is diffusion?

Diffusion is the movement of molecules from an area of high concentration to an area of low concentration.

What is the significance of particle size in dissolution?

Smaller particles generally lead to faster dissolution due to increased surface area.

What is the effect of salt formation on solubility?

Salt formation can improve the solubility of a drug.

What is solid dispersion in drug formulation?

Solid dispersion involves a drug being dispersed in a carrier to enhance solubility.

What is complexation in the context of drug solubility?

Complexation refers to a drug associating with another molecule to improve solubility.