Physical Pharmacy Exam 2 Self Assessments

Aspirin is a weakly acidic drug with a pKa of 3.5. Select all statements from below that are true:

At pH 3.5 aspirin is 50% ionized

At pH 3.5, aspirin is 50% unionized

At pH of 6.5, aspirin is mostly ionized

At pH of 2.5, aspirin is mostly unionized

At pH 3.5 aspirin is 50% ionized

At pH 3.5, aspirin is 50% unionized

At pH of 6.5, aspirin is mostly ionized

At pH of 2.5, aspirin is mostly unionized

The pKa of codeine, a weak base, is 8.2. This means:

At a pH of 7.2, codeine is mostly ionized

To improve dissolution of crystal sugar in water, you may heat it. This suggests that:

It is an endothermic reaction

Morphine is a weak base with a pKa of 7.9. This information suggests that:

At pH 6.9 morphine is mostly ionized

For a drug molecule that doesn't undergo any ionization, which of the following statements is true? 

Log P = Log D

For ionizable drugs, when used as a co-solvent, semi-polar solvents like alcohol or propylene glycol will improve the solubility of ionized portion of the drug.

False

For saturated solutions of aspirin and acetaminophen, you expect comparable (or same) molar concentrations of the drug.

False

In order for a drug to be absorbed orally, it needs to be soluble within the GI lumen

True

For a solution of CO2 in water, an increase in temperature would improve CO2 solubility

False

Lugol's solution is used to supplement iodine for patients with iodine deficiency. According to its label, it has 20 mg/ml of iodine and 40 mg/ml of potassium iodide in distilled water. Thus, according to USP, this concentrations are respectively expressed as:

2%w/v and 4% w/v

When you add a spoon full of sugar in your coffee and stir, which of the following parameters of Noyce Whitney equation are you directly affecting, that improves dissolution?

Stagnant layer thickness

In your own words, how would you explain the difference between solubility and dissolution of a drug?

Solubility is a physical constant. In a given liquid, at a given temperature, the equilibrium solubility of a drug is a constant.  Dissolution indicates how quickly the drug reaches maximum equilibrium solubility. Thus, dissolution is a rate process and indicates the speed of solubility. Unlike solubility, you can change dissolution rate by altering, say, the particle size of the drug.

What is the most important reason that glucose is soluble in water?

Glucose can form H-bonds with water

Within a series of structurally related molecules, as boiling point increases, this is what you may notice:

Water solubility is reduced

Why is n-octanol and not some other lipohillic solvent is used for determining the partition coefficient of drugs (LogP)?

Like cellular bilayer lipids, it has some polarity (due to the OH group) and a lot of lipophilicity (due to the long 8 Carbon chain).  

For a drug to be orally absorbed, which of the following properties is highly desirable?

Some water solubility and some lipid solubility

In terms of their aqueous solubility, which of the following inorganic salt pairs are listed in a lower to higher solubility order? 

BaSO₄, NH₄Cl

Which of the following is true regarding organic solvents?

They can extract active principles 

The key reason Iodine mixed with potassium iodide has improved aqueous solubility is:

I3- complex

USP defines very soluble drug as: 1 part of drug soluble in 1 part of a liquid like water. One part here means: (select all that apply)

gram

mL

grain

tea spoon

microliter

gram and mL

According to Noyce Whitney equation, to improve dissolution, you might do the following change to your tablet formulation

Reduce the drug's average particle size

According to Noyes-Whitney equation, as the stagnant layer thickness increases, the rate of dissolution decreases

True

Unlike water molecules in the bulk phase, water molecules at the top face:

attraction from below

The interaction between one of the following pairs of matter may be described as surface tension:

air/water

Non-homogeneous pharmaceutical systems experience significant interfacial tension and are considered to be thermodynamically unstable. Which of the following are examples of such systems?

emulsions and suspensions

The role of pulmonary surfactant is to:

reduce surface tension between air and the alveoli

Which of the following conditions will enable the spreading of the material Z over material M

Adhesion forces between Z and M is greater than cohesion forces within Z 

Regarding water and hexane's molecular interactions, which of the following statements is true?

hexane spreads on water

Between a solid drug particle and a liquid, which of the following conditions may indicate increased wetting?

small contact angle

The reason mercury forms a positive miniscus in a glass test tube is because:

cohesion force is greater than adhesion 

With regard to surface active agents, which of the following is a true statement?

They are amphiphillic

Anionic and cationic surfactants are often used in combination to maximize stability in formulations.

False

Non-ionic surfactants like SPANS are used to stabilize oil/water emulsions.  

False

As temperature increases, adsorption becomes more efficient.  Note: this topic may not have been covered in class yet. If so, wait for the following class.

False

Hair conditioners and disinfectant sprays almost always contain this type of surfactants:

Cationic

Which of the following characterstics are associated with anionic surfactants? (multi-select)

Highly irritant to skin/mucous membranes

Frequently present ingredient in disinfectant sprays

Bile salts are a great example of anioinic surfactants

Produce minimum froth

Are used in combination with nonionic surfactants

Highly irritant to skin/mucous membranes

Bile salts are a great example of anioinic surfactants

Are used in combinatoin with nonionic surfactants

A preferred type of surfactant used in baby shampoo is?

Nonionic (e.g. Tween 80)

Which of the following type of surfactants are known to support small and creamy bubbles and therefore commonly used in modern shampoos and body washes?  

Zwitterionic

Match the surfactant with its function

Anionic 1. Makes creamy bubbles

Zwitterionic 2. Highly irritant to the skin

Cationic 3. A common ingredient in hair conditioners

Nonionic 4. Is relatively nonirritant to the skin

Anionic → 2. highly irritant to the skin

Zwitterionic → 1. makes creamy bubbles

Cationic → 3. Common ingredient in hair conditioners

Nonionic → 4. is relatively nonirritant to skin

In an oil in water emulsion, water is the (two words)

Continuous phase

In an water in oil emulsion, water is considered as (two words):

Dispersed phase

When you add a small quantity of Tween 80 to water, this is what is expected to happen:

Surfactant molecules will gather at the air/water interface