States of Matter (1)

non polar molecule

all nuclei in the molecule have similar electron withdrawing abilites

polar molecule

nuclei in the molecule have different electron withdrawing abilities

electronegativity

the ability of the nucleus to withdraw or attract electrons

Van der Waal forces

proportional to the molecular weight (higher the molecular weight, the stronger the interaction)

what is important to remember about vapor pressure?

the stronger the intermolecular forces, the lower the number of molecules that can escape the liquid state, the lower the vapor pressure

boiling point

the temperature at which the VP of a liquid equals the atmospheric pressure

advantages of aerosols as a dosage form:

-deliver medications as fine droplets deep into the alveoli for instant response

-minimize irritation to damaged skin

methods to use to polarize non-polar gas molecules to turn gas into liquid:

1. applying high pressure

2. decreasing their kinetic energy by cooling them down to very low temperatures

how can the volatility of an unfamiliar liquid be assessed?

by comparing its VP and/or BP to those of water memorizing that highly volatile liquids have high VP but low BP

non-polar molecules have lower BP than polar molecules because…

non-polar molecules are held together by the weak induced dipole-induced dipole forces

polar molecules have high BP because…

the molecules associate by the strong polar interactions such as H-bonding

branching of molecules weakens their associations therefore…

lowers the BP

the higher the BP…

the lower the VP at room temp

what is the most important point to memorize about solid drugs?

solid drugs are only absorbed from solution form

what are the two states solids exist in?

1. crystalline

2. amorphous

crystalline

-arranged in fixed geometric patterns

-sharp well defined melting points

-lower solubility

-higher stability

amorphous

-random arrangement of units

-do not melt but soften over a temperature range

-more soluble

-less stable (transform to crystalline over time)

which form of solid drugs are more biologically active?

amorphous

which solid drug form is more biologically inactive?

crystalline

polymorphism

when the molecules of the same compound arrange in more than one crystal form

why is polymorphism a problem in the pharmaceutical industry?

the different crystal forms of the same active ingredient may have different aqueous solubilities which leads to varied biological response

all pharmaceutical products should exist as…

a homogenous one phase system to ensure equal distribution if active ingredients in all parts of the product to ensure consistent dosing

ointments

made entirely of non-polar fatty substances like vaseline or bees wax

creams

mixtures of oils and water