Lecture 3: Solution Dosage Form Flashcards
(78 cards)
What is a solution?
A thermodynamically stable, one-phase system composed of two or more components, one of which is completely dissolved in the other
Why is a solution homogeneous?
Because the solute is dispersed throughout the solvent in molecular or ionic sized particles
What is the most common solvent for pharmaceutical solutions?
Water
What are 4 common solvents for pharmaceutical solutions?
1) Ethanol
2) Glycerin
3) Propylene glycol
4) Isopropyl alcohol
What must be considered when choosing a solvent for a solution?
1) Must completely dissolve the drug and other solid ingredients at the desired concentration
2) Be non-toxic and safe for ingestion or topical application
3) Be aesthetically acceptable to the patient
What are 5 advantages to solutions as a dose form?
1) Completely homogeneous
2) Immediately available for absorption into the body
3) Flexible in terms of dose adjustment
4) Can be used by any route of administration
5) Can be administered to patients who cannot swallow tablets or capsules
What are 5 disadvantages to solutions as a dose form?
1) Drugs less stable when in solution
2) Some drugs not soluble in solvents that are acceptable for pharmaceutical use
3) Drugs with objectionable taste require taste masking
4) Heavier and bulkier than solids
5) Require measurement by patient or caregiver
How can rate of dissolution be increased?
1) Heating – but the solvent must be non-volatile and the solute stable to heat
2) Stirring
3) Reduction of particle size
What are 2 characteristics that a solution must have for it to be considered “pharmaceutically elegant”?
1) Should be very clear
2) Small particulates should be removed by filtration
What does solubility of an agent indicate?
The maximum concentration to which a solution can be prepared using that agent, solvent, and temperature
What is involved in the process of dissolution?
The breaking of solvent-solvent and solute-solute forces and establishment of solvent-solute forces
What is a factor in solubility?
Temperature
What are factors of rate of dissolution?
Particle size and agitation
When is pH a significant factor in solubility?
When the drug is ionizable
For dissolution, when is heat required?
To break the bonds holding the solute together and the solvent together
For dissolution, when is heat released?
When the new solute-solvent bonds form
When will a dissolution be endothermic?
When the heat given off is less than the heat required
When will a dissolution be exothermic?
When the heat given off is more than the heat required
True or false: the volumes of the components of a solution are additive
False, they are not additive
What happens when a salt is added to a fixed volume of water?
The volume will likely change
What is the proper procedure when making 100 mL of a 20% solution of NaCl?
- Weigh proper amount of NaCl
- Dissolve in about 80 mL of water
- Transfer to a measuring cylinder and add enough water to make 100 mL
What is a displacement volume?
The volume occupied by the powder when a suitable diluent is added during reconstitution
When is a displacement volume particularly important?
When dose is needed only for a proportion of the vial content
When does displacement volume vary?
For each drug, for each strength of drug, and for different brands/manufacturers formulas
