Solutions (Part 1) Flashcards
Define pharmaceutical solutions
liquid preparations that contain one or more chemical substances dissolved in a suitable solvent OR mixture of mutually miscible solvents
Name FIVE factors that affect solubility
-attractive forces
-repulsive forces
-van der waals forces (dipole-dipole) - dipolar molecules
-ion-dipole force
-hydrogen bond
dipole-dipole forces are also known as…
ven der waal forces
hydrogen bonding occurs between….
polar and non polar molecules and ions
hydrogen bond is a hydrogen molecule attached to….
oxygen, nitrogen, or fluorine
in a solution, what are the solutes?
medicinal agents OR additional agents (excipients) such as color, flavor, sweetness, or stability)
to achieve the solute-solvent attraction, what has to happen?
the solute-solute forces and the solvent-solvent forces must be broken to achieve the solute-solvent attraction
the SOLUBILITY of an agent in a particular solvent indicates what?
the maximum concentration of the drug in solution
when is a solution said to be saturated?
when a solvent at a given temp has dissolved all of the solute possible
what is unique about Calcium Hydroxide Topical Solution, USP?
calcium has negative heat effect. the solubility of calcium hydroxide DECREASES with rising temperature
name the solute(s) and solvent(s) of Calcium Hydroxide Topical Solution, USP
1 solute: Calcium hydroxide (excess amount)
1 solvent: purified water
what is the % w/v of Calcium Hydroxide Topical Solution USP?
explain
0.14% w/v
0.14 g solute in 100mL solution
this is the solubility of calcium hydroxide at room temperature
VERY LOW SOLUBILITY
Name the solute and solvent of Potassium Iodide Oral Solution USP
1 solute: potassium iodide
1 solvent: purified water
give the solubility of Potassium Iodide Oral Solution USP at room temp.
100% w/v
100 g of solute in 100 mL solution
What can be changed in regards to the SOLUTE to increase solubility?
-solubilizing agent (excipient)
-using a chemical salt of the API (medicinal agent)
Is it preferred to alter the solubility by changing the API or changing the solvent(s)?
preferred to change the solvents.
How can the solvent be altered to adjust the solubility of a drug?
substitution (in part or whole)
ie: use of a cosolvent is done most of the time
Explain how the SOLUTION ITSELF can be altered to adjust the solubility of the API
changing the pH or the temperature of the final solution.
pH of the solution is adjusted based on what equation?
hendersen hasselbach equation
why is changing the temperature of the final solution NOT really used to increase solubility?
because the solution is stored at room temperature usually and the solubility will change once the heat is removed in the laboratory setting
Explain how altering the solution of iodine granules + purified water can increase solubility.
iodine granules by itself is not very soluble in purified water. 1 g of solute in 3000mL solution (0.033%w/v)
however, Iodine Topical Solution USP has the iodine granules (2%) and 2.4% of sodium iodide (SERVES AS A SOLUBILIZING AGENT) as the solutes and purified water as the solvent.
this makes the solution much more soluble
SOLUTES: iodine and sodium iodide (solubilizing agent; excipient)
SOLVENT: the same – purified water
Name the USP relative terms of solubility and the meaning behind them
very soluble
freely soluble
soluble
sparingly soluble
slightly soluble
very slightly soluble
Practically insoluble/insoluble
“parts of solvent required to dissolve 1 part of the solute”
very soluble: <1
freely soluble: 1-10
soluble: 10-30
sparingly soluble: 30-100
slightly soluble: 100-1,000
very slightly soluble: 1,000-10,000
practically insoluble/insoluble: >10,000
“parts of solvent required to dissolve 1 part of the solute”
be specific…
mL of solvent required to dissolve 1 g of solute
Explain what happens when you convert a drug to its salt form
when a drug is converted to its salt form, the drug’s solubility in water is increased due to the “like dissolves like” principle (both are polar)
however, converting to salt form means that if alcohol is the solvent, much more of it is required to dissolve this salt form of the drug.
what is the salt form of codeine? explain the process in getting to this point
the acceptable salt form of codeine is codeine PHOSPHATE.
Codeine sulfate was originally made, but this salt form turned out to be only soluble in water, and very slightly soluble in alcohol (1,280)
so, codeine phosphate was created to combat this issue of insolubility in alcohol. Codeine phosphate is freely soluble in water, and slightly soluble (325) in alcohol, which is much more acceptable than the 1,280 of codeine sulfate.
which are more soluble in alcohol – organic bases or their corresponding salt forms?
organic bases
name the 10 POLAR GROUPS from the slides
OH
CO
CHO
COH
CH2OH
COOH
CHOH
NO2
NH2
SO3H
Are most drugs organic or inorganic? What does organic/inorganic mean?
must drugs are organic, meaning that they contain carbon