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Unit-4 Pharmaceutics > Ceutics > Flashcards

Ceutics Flashcards

1
Q

What will you come to know about in this chapter?

A

Solubility expression, mechanisms of solute-solvent interaction, ideal solubility parameters, solvation and association, factors influencing drug solubility, diffusion principles in biological systems

These objectives guide the learning outcomes of the chapter.

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2
Q

What are the main aspects of solubility discussed in this chapter?

A

Solubility of gas in liquids, liquids in liquids, Raoult’s Law, critical solutions temperature (CST), distribution law

These aspects cover both theoretical and practical applications of solubility.

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3
Q

What is Raoult’s Law?

A

A principle that relates the vapor pressure of a solvent to the concentration of solute

It applies to ideal solutions and is essential for understanding solubility in mixtures.

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4
Q

What does the Critical Solutions Temperature (CST) indicate?

A

The temperature at which two components of a mixture become completely miscible

CST is crucial in understanding solubility behavior in various temperatures.

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5
Q

What is the Distribution Law or Nernst’s distribution law?

A

A law that describes how a solute distributes itself between two immiscible solvents

It has applications in extraction processes and limitations in certain conditions.

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6
Q

Fill in the blank: Factors influencing the _______ of drugs are discussed in this chapter.

A

[solubility]

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7
Q

What are the mechanisms of solute-solvent interaction?

A

Interactions such as hydrogen bonding, van der Waals forces, and ionic interactions

These interactions play a critical role in determining solubility.

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8
Q

What is meant by ‘ideal solubility parameters’?

A

Quantitative measures that predict how well a solute will dissolve in a solvent

They help in formulating drugs and understanding solubility.

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9
Q

What are the principles of diffusion in biological systems?

A

The movement of molecules from an area of higher concentration to an area of lower concentration

This principle is essential for drug delivery and absorption.

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10
Q

What types of solubility are explored in this chapter?

A

Solubility of gas in liquids, liquids in liquids

Each type has unique characteristics and applications.

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11
Q

What are the applications of Distribution Law?

A

Used in extraction processes, drug formulation, and pharmacokinetics

Understanding these applications is vital for practical uses in chemistry and pharmacology.

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12
Q

What are the limitations of Distribution Law?

A

Assumes ideal behavior, may not apply to highly polar or ionic compounds

Recognizing these limitations is important for accurate predictions in real-world scenarios.

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13
Q

What is solubility defined as in quantitative terms?

A

The concentration of solute in a saturated solution at a particular temperature

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14
Q

How can solubility be qualitatively defined?

A

The spontaneous interaction of two or more substances to form a homogeneous molecular dispersion

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15
Q

What factors affect the solubility of a solute?

A
  • Physical and chemical properties of solute and solvent
  • Temperature
  • Pressure
  • pH of the solution
  • Particle size of the solute
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16
Q

Why is understanding solubility important for pharmacists?

A

It is a key parameter affecting the formulation of dosage forms

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17
Q

What are some phenomena that make solubility an important criterion?

A
  • Choice of solvent for liquid formulation
  • Dissolution of drugs
  • Bioavailability of drugs
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18
Q

What is a solution?

A

A system in which solutes are completely dissolved in solvent and remain present at the molecular size

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19
Q

Define solute.

A

The substance which is dissolved in the solvent

20
Q

Define solvent.

A

The component in which solute is dissolved

21
Q

What is a saturated solution?

A

A solution in which solute is dissolved up to its maximum limit of solubility at a given temperature and pressure

22
Q

What is an unsaturated solution?

A

A solution in which dissolved solute is in a concentration below the required amount necessary for complete saturation

23
Q

What is a supersaturated solution?

A

A solution which contains more of the dissolved solute than it would normally contain in a saturated state

24
Q

How is solubility expressed according to the United States Pharmacopeia (USP)?

A

As parts of solvent required for one part solute

25
Q

List the solubility classifications provided by the USP.

A
  • Very soluble
  • Freely soluble
  • Soluble
  • Sparingly soluble
  • Slightly soluble
  • Very slightly soluble
  • Practically insoluble
26
Q

What principle is used in selecting a good solvent?

A

‘Like dissolves like’

27
Q

What happens if the attraction force between solute and solvent (X-Y) is less than that within the solvent (X-X)?

A

The solvent molecule has a greater affinity for its own molecules than for the solute molecules

28
Q

Provide an example where a solute is insoluble in a solvent due to strong solvent-solvent attraction.

A

Benzene is almost completely insoluble in water

29
Q

What occurs if the attraction between solute molecules (Y-Y) is much greater than between solute and solvent (X-Y)?

A

The solvent will not be able to break the binding forces between solute molecules

30
Q

What is required to dissolve sodium chloride in a solvent?

A

A highly polar solvent such as water

31
Q

What is the application of barrier in drug movement?

A

The application involves dissolution of drug from tablets, granules, ointments, and suppositories; release from sustained or controlled release dosage forms; absorption, distribution, and elimination of drug in biological systems.

32
Q

What governs the movement of drug molecules in biological systems?

A

Movement is governed by the concentration gradient, moving from higher concentration to lower concentration through biological membranes or barriers.

33
Q

What is Fick’s First Law of Diffusion?

A

Fick’s First Law states that the rate of drug transport across a unit cross-section of a barrier (flux) is directly proportional to the concentration gradient.

34
Q

What is the formula for flux according to Fick’s First Law?

A

J = -D (dC/dx)

Where J is the flux, D is the diffusion coefficient, C is the concentration, and x is the distance.

35
Q

What does the negative sign in Fick’s First Law indicate?

A

The negative sign indicates that diffusion occurs in the direction of decreasing concentration.

36
Q

What factors influence the diffusion coefficient (D)?

A

The diffusion coefficient may be influenced by:
* Concentration
* Temperature
* Pressure
* Solvent properties
* Chemical nature of the diffusant.

37
Q

What does Fick’s Second Law describe?

A

Fick’s Second Law describes how diffusion causes concentration to change with time.

38
Q

What is the primary equation for Fick’s Second Law?

A

∂C/∂t = D ∂²C/∂x²

This equation describes the change in concentration C over time t.

39
Q

How is the solubility of gas in liquids defined?

A

The solubility of gas is the amount of gas dissolved in a liquid that is in equilibrium with the pure gas above the solution.

40
Q

What factors affect the solubility of gas in liquids?

A

The solubility of gas depends on:
* Temperature
* Pressure
* Salt present
* Chemical reactions
* Micellar solubilization.

41
Q

How does temperature affect the solubility of gas in liquids?

A

As temperature increases, the solubility of gas in liquid decreases.

42
Q

What is the effect of pressure on gas solubility in liquids?

A

The solubility of each gas at constant temperature is directly proportional to its own partial pressure.

43
Q

Fill in the blank: The solubility of oxygen in water at 10°C is ______ ml per 100 ml of water.

A

3.25

44
Q

True or False: At higher temperatures, more gas remains dissolved in the liquid.

A

False

45
Q

What is recommended before opening ammonia bottles?

A

Ammonia bottles should be cooled before opening and the stopper should be covered with cloth.

46
Q

What is the significance of heating water to 90°C in distillation?

A

Heating water to 90°C or higher removes dissolved gases before distillation.

Unit-4 Pharmaceutics (2 decks)

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