Solutions Flashcards
Solutions
- Liquid preparations with one or more substances dissolved in a suitable solvent(s)
- Can be oral, topical, optic, ophthalmic, injections
Different than suspensions which are solid particles SUSPENDED in liquid, not dissolved.
Solution Advantages
- Faster onset of action
- Dose uniformity
- Easier to swallow
- Reduces stomach irritation
- More variability with dose strengths
Solution Disadvantages
- More likely to take the incorrect dose
- Taste
- Messier than tablet
- Bulky to stores
- StabilityAcc
Solubility Clinical Relevance
- Solubility affects bioavailability and therapeutic response
- Need enough drug in solutions to reach therapeutically meaningful concentrations (related to the drugs solubility and permeability)
- Stability of drug is also connected to its solubility
Dissolution
The process of the solute dissolving in the solvent, which could take a significant amount of time depending on the conditions.
Solubility is a property of the solute that describes how far the solute would dissolve into a solvent
Biopharmaceutics Classification System (BCS)
- Class 1 = highly soluble and permeable (Ex. Diltiazem)
- Class 2 = high permeability but low solubility (Ex. Nifedipine)
- Class 3 = low permeability but high solubility (Ex. Insulin)
- Class 4 = low permeability and solubility (Ex. Taxol)
Solubility
- spontaneous interaction of 2+ substances to form homogeneous molecular dispersion
- [] of solute in saturated solution at a specific temperature
Saturated Solution
No more solute can be dissolved in solvent
Un-/sub-saturated Solution
Dissolved solute is below the saturated concentration (can add more solute)
Supersaturated Solution
Contain more solute than it would normally contain, usually manipulated with temperature or pressure to achieve.
Expressing Solubility
-# mLs or solvent in which 1 gram of solute will dissolve
-Molality (moles/kg of solvent)
-Molarity (moles/L of Solution)
Percentages (w/w, w/v, v/v)
Relative Solubility Terms
Types of Solutions
- Aqueous
- Syrups - aqueous solutions containing sugar
- Elixirs - sweetened hydroalcoholic solutions
- Aromatic Waters - aromatic materials in aqueous solvent
- Tinctures/Fluidextracts - extract active from crude drug, usually contains ethanol
Aqueous Solvent Types
- Purified water - less impurities; purified by distillation, ion exchange, or reverse osmosis
- Ethyl alcohol
- Rubbing alcohol - topicals
- Glycerin - clear, sweet, viscous
- Propylene glycol - viscous
Non-aqueous Solvents
- Fixed oils of vegetable origin (non-water miscible)
- Better for external applications
- Wide manufacturing processing
- Limited for parenterals (olive, sesame, maize, cottonseed, castor oil)
must consider cost, flammability, stability, comparability, and toxicity
