30 Questions
What is the purpose of maintaining the freezing point depression of the drug solution at -0.52°C?
To ensure the drug solution remains isotonic.
What is the key factor that needs to be adjusted to make the drug solution isotonic?
Concentration of the drug
How is the required percentage weight/volume (w/v) of an adjusting substance calculated?
(0.52 - d) / a
What happens to the freezing point depression if the AT value of the adjusting substance (a) increases?
The freezing point depression increases.
If the % w/v of an adjusting substance needed is calculated to be 5%, what could be a possible value for 'd' in this scenario?
-0.2
In equation (1), what does 'Total drug solution AT' represent?
The freezing point depression of the complete drug solution
What is the advantage of using a glass electrode for pH measurement?
High accuracy in pH measurement
Why is the cost of a pH meter considered a disadvantage over the colorimetric method?
The pH meter is more expensive
What role do pH indicators play in determining the pH of a test solution?
Producing a color change to indicate pH
Why are glass electrodes not affected by the oxidation-reduction system?
They establish equilibrium rapidly
What characteristic makes a universal indicator different from other indicators?
It gives different color shades at different pH levels
Why is the method using a glass electrode not suitable for viscous solutions and gels?
Viscous solutions hinder proper equilibrium establishment
What is the pH range for Methyl yellow indicator?
3.1-4.4
When does the colour change occur for Methyl red indicator?
Red-yellow
What is the pH range for Thymol blue indicator?
8.0-9.6
What is the main purpose of adjusting the pH of pharmaceutical formulations?
Enhancing solubility
What does buffer capacity refer to?
The amount of acid/base required to produce a unit change in pH
Why is it important to add a buffer of desired pH to enzyme preparations?
To optimize biological activity
What is the range of buffer capacity generally considered adequate for pharmaceutical buffers?
0.05 to 0.5
Which buffer system cannot be used to stabilize a solution for oral or parenteral administration due to its toxic effects?
Borate buffer
What is the pH range of blood that poses a danger to life according to the text?
7.0 to 7.8
Which primary buffer system is present in plasma according to the text?
Carbonic acid-bicarbonate system
What is the total buffer capacity for whole blood as indicated in the text?
0.0315
What are the two secondary buffer systems present in erythrocytes according to the text?
Haemoglobin/oxyhemoglobin system and acid/alkali salts of phosphoric acid system
What is the purpose of the White Vincent method in the context of ophthalmic solutions?
To make an isotonic solution by adding drugs and diluting vehicles
In the context of Class II methods, what does the sodium chloride equivalent refer to?
The weight of the drug multiplied by the equivalent amount of sodium chloride
What is the significance of the ratio 100/0.9 in the White Vincent method?
It represents the volume of isotonic solution that can be prepared
What does the term 'tonicity' refer to in relation to ophthalmic solutions?
The osmotic pressure of the solution
How does the White Vincent method simplify the process of preparing ophthalmic solutions?
By adjusting both the tonicity and pH simultaneously
What quantity does 0.063g of sodium chloride represent in terms of procaine hydrochloride weight equivalence?
$0.063W$
Learn about the process of measuring pH using a glass electrode, including rinsing, immersing in the test solution, and adjusting pH levels with acid or base solutions. Understand the advantages of using a glass electrode for pH measurement.
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