Exam 2- Lecture 8 (Pharmaceutical Solutions) Flashcards
What is a solution? What are the components?
Mixture of two or more compounds that form homogenous molecular dispersion. Solute and solvent
What are the types of solvents?
Polar Non-polar Semi-polar
What the characteristics of a polar solvent?
High dielectric constant: able to induce the charge on to the solvent Break covalent bonds potentially produces electrolytes by acid base reduction Dipole interaction forces
What are the characteristics of a non-polar solvent
Low dielectric constant Cannot break bonds Weak electrolytes
What are the characteristics of a semi-polar solvent?
-Induce certain amount of polarity in a non-polar solvent -Act as an intermediate
Common solvents include:
Water Alcohol Glycerin Polyethylene glycol Propylene glycol
What is the most common solvent? Why?
Water No toxicity, compatible with body
There are different types of water, what type is used for preparations of solutions? For wounds/cleaning?
USP purified water USP for irrigation
Ethyl-alcohol is used in the pharmacy. True or false
True
Are there limitations to the amount of alcohol that can be in OTC products?
Yes
- 10% (OTC)
- up to 45% (prescription products)
What is a saturated solution?
Solution in which the maximum the solute the solvent can hold is reached
What is a unsaturated solution?
Solvent holds less solute than its maximum
Supersaturated solution is what?
- Solvent holds more than its maximum at a given temperature
- These bonds are very unstable
- Crystallation can be stimulated by adding a seed or scratching the side of a beaker.
Solubility alteration includes:
Microionization
Co-solvent- having a second solvent in the water based system to enhance the solubility of the drug
Pro-drug
Complexation
Superfactants
Micronization
reducing particle size
Co-solvent
- semi-polar solvents can enhance solubility of poorly soluble drugs
- adding a second solvent into the water based system
- drawback: concentration of co-solvent will go down in the system, causing precipitation and irritation to the GI tract
- works better when you have a non-polar solvent
Pro-drug
- inactive but can become active by adding a polar group along the surface to increase solubility by increasing the hydrogen bonding of molecules between drug an water.
- turns into an active drug when drug is administered and gets a change through enzymatic reaction or from temperature
Complexation
2 or more molecules to form non-covalent complex with higher solubility than the drug itself. (CD- cyclodextrin)
- to figure out what ratio gives you a better solubility
- dissolves a non soluble solute in water by putting it on the inside where the outside is water soluble, so the whole thing will dissolve
- makes a non soluble solute soluble
Superfactants
- detergents that have affinity for polar (head) and non-polar (tail)
- laundry detergent
- have hydrophilic and hydrophobic group
pH
you have to choose a pH that is not at one extreme or another
