Pharmaceutics: Physical Pharmacy and States of Matter

quiz tuesday

pharma

was derived from the Greek word “Pharmakon”, which means “drug”

pharmaceutics

Converts a drug into a medicine’

Mainly concerned with the scientific and technological aspects of the design and manufacture of dosage forms

drug

any chemical agent that can interact with the living system and produce a biological response

physical pharmacy

Focused on studying the physical and chemical properties of drugs and their dosage forms.

Studies the essential physicochemical properties and processes involved in transforming a drug (mostly in crystalline form) into a usable dosage form

Intermolecular forces

Weak electrostatic attractions between different molecules determining physical properties like boiling and melting points of a compound.

intramolecular forces

are strong chemical bonds (covalent, ionic, or metallic) within a single molecule, holding it together and affecting chemical properties

The intermolecular forces between the molecules/atoms of a substance.

What does the state in which a substance will exist depend on?

True

When molecules interact, both attractive and repulsive forces are involved.

more condensed phase

if the attractive forces between molecules are stronger than the repulsive forces, the molecules will come together and form a ___

kinetic energy

These attractive forces which hold the molecules or atoms together, can be overcome by sufficient ___

less condensed phase

Once overcome by sufficient kinetic energy it leads to the formation of a ___-

cohesive forces

represent the attractive forces between similar molecules

cohesive forces and adhesive forces

there are two types of attractive forces

adhesive forces

are those involved in attraction between different molecules

repulsive forces

Separation of molecules takes place due to?

Van der Waals forces, Ion dipole forces, hydrogen bonding, hydrophobic interactions

What are the four types of intermolecular attractive forces?

Van der Waals Forces

weak forces that involve the dispersion of charges across molecules → dipole (partial charges)

Keesom Forces (dipole-dipole)

Molecules with both partial positive and partial negative charges align themselves so the negative pole of one molecule interacts with the positive pole of another molecule

WEAK strength due to the partial charges

Ex. water and peptide bonds in peptide/protein.

debye forces (dipole-induced dipole)

can occur when a permanent dipole in a polar molecule produces a temporary electrical dipole in a neighboring nonpolar molecule

WEAKER than Keesom forces

London Forces (induced dipole-induced dipole or dispersion forces)

WEAKEST intermolecular forces

Temporary attractive force that results when electrons in two adjacent atoms occupy positions that make atoms form temporary dipoles,

cause nonpolar substances to condense to liquids and freeze into solids when temperatures are lowered sufficiently

Ion-dipole Forces

Involved in the interaction of polar molecules with molecules possessing either positive or negative charges

Plays a crucial role in the stability of ionic crystalline substances like NaCl in water

hydrogen bonds

The interaction between a molecule containing a hydrogen atom and a strongly electronegative atom such as fluorine, oxygen, nitrogen, and sulfur

Occurs in ice and liquid water and accounts for water’s high boiling point

can be inter OR intramolecular

STRONG because they are partially covalent

hydrogen

Has a small size and a large electrostatic field, resulting in its ability to move close to an electronegative atom and form an electrostatic interaction, hydrogen bond, or hydrogen bridge

Hydrophobic interactions

attractive forces between nonpolar atoms and molecules in water

cause nonpolar species to come closer to each other

critical for the stabilization of the structure of many molecules

temperature

Kinetic energy is directly proportional to?

Intermolecular forces

Kinetic energy under nonideal conditions is governed by?

intermolecular, interatomic, or ionic forces

Molecules, atoms, and ions in the solid state are tightly held together in proximity by?

fixed position

In the solid state, atoms can vibrate only about a?

mesophase

This phase lies between the liquid and crystalline solid phases

Some molecules exhibit this fourth phase

supercritical fluid

lies between liquids and gases

Random Paths

Gas molecules travel in __

Exert pressure

When gas molecules collide with each other and with the walls of the container in which they are confined, and so they __

Gas Molecules

They are molecules that have higher kinetic energy

• They produce rapid motions

• They are held together by weak intermolecular forces

• They have no regular shape

• They are capable of filling all available space

• They are compressible

• Many of them are invisible
• Many of them are invisible

Ideal gas law

At normal temperature and pressure, gases such as oxygen, nitrogen, and

hydrogen can be defined by ___

Useful in calculating the properties of gases at atmospheric pressure and temperatures higher than their boiling points

definite volume

Liquids are denser than gases and occupy a

Temperature and pressure

Transition from a gas to a liquid and from liquid to solid depends on what?

kinetic energy

When a gas molecule is cooled it loses some of its ___ in the form of heat

decreases

When a gas is cooled the velocity of the molecule __

critical pressure

If the temperature is raised sufficiently, it can reach a value above which it is impossible to liquefy a gas irrespective of the pressure applied. What is this value called?

critical pressure

The pressure required to liquefy a gas at its critical temperature is called __? Which is also the highest vapor pressure a liquid can have

True

True or False: Gases can be liquefied under high pressure in a closed chamber as long as

the chamber is maintained below the critical temperature. When pressure is reduced, the molecules expand, and the liquid reverts to a gas.

Pharmaceutical aerosols

The reversible change of state of gases being able to turn liquid is the basic principle involved in the preparation of __

propellant

In pharmaceutical aerosols, the drug is dissolved or suspended in a material that is liquid under the pressure conditions that exist inside the container but forms a gas under normal atmospheric conditions. What is this material?

True

True or False: Some molecules have more energy and higher velocities than others at any moment due to kinetic energy not being distributed evenly among molecules

Gaseous State

When a liquid is placed in an evacuated container at constant temperature, molecules that have the break away from the surface of the liquid and pass into the___. Some molecules will return to the liquid state or condense.

Saturated

When the rate of condensation is equal to the rate of vaporization at a definite temperature, the vapor becomes ___ and a dynamic equilibrium is established

equilibrium vapor pressure

The pressure of the saturated vapor above the liquid is then known as

does not

The presence of gas, like air, above the liquid results in a decrease in the rate of vaporization but (does not/does) affect the equilibrium pressure of the vapor.

boiling point

The temperature at which the vapor pressure of the liquid equals the external or atmospheric pressure

May also be considered the temperature at which thermal agitation can overcome the attractive forces between the molecules of a liquid

magnitude of the attractive forces of a molecule

similar to the heat of vaporization and the vapor pressure at a definite temperature, the boiling point can provide a rough indication of the___

Greater

Attractive van der Waals forces become ___ with the increasing number of atoms

strong

Solids tend to have __ intermolecular forces

little

solids have very ___ kinetic energy

crystalline, amorphous, polymeric

three main types of solids

repetitious three-dimensional lattice

In crystalline solids molecules or atoms are arranged in ___ units indefinitely throughout the crystal

crystallization

occurs by the precipitation of the compound out of solution and into an ordered array.

highest

Cubic system exhibits the ___ symmetry

lower

Triclinic system exhibits the __ symmetry

lower symmetry

Drug substance molecules are usually found in what system?

atoms, molecules, or ions

Units that make up the crystal structure

ionic and atomic

What crystals are hard and brittle and have high melting points?

Molecular

What crystal is soft and have relatively low melting points?

melting point

a single temperature at which the onset or complete melting is first observed.

homomeric crystals

composed of identical molecules or atoms

heteromeric crystals

composed of more than one type of molecule or atoms ex. solvates, salt crystals, and cocrystals

polymorphism

means that substances exist in more than one crystalline form.

In this case, each form is known as a polymorph.

They are chemical entities that exist in more than one crystalline structure.

changes in intermolecular bonding pattern, conformational change in the molecule, and/or change in the molecular orientation between neighboring molecules in the solid.

the change in the crystalline forms (polymorphism) arises from?

different

Polymorphs have __ stabilities and can convert from the metastable form at a temperature to the stable form

yes

Do polymorphs exhibit different melting points and solubilities?

differences in solubilities

Polymorphism is of great important because the ___ can affect the rate of drug dissolution, resulting in differences in the therapeutic activity of the different polymorphs.

salts

The lattice can also incorporate other molecules such as acids and bases to form?

weak bases or weak acids

Most drugs are either

amorphous

A solid material is referred to as __ when its molecules are arranged in a somewhat random manner, as in the liquid state.

amorphous

What type of solids tend to flow when subjected to sufficient pressure over time, don’t have definite melting points but are defined by a glass transition temperature?

glass transition temperature (Tg)

The temperature at which an amorphous material converts from a glass to a supercooled liquid upon heating

Less stable (physically)

Due to relatively weak interactions between their molecules, amorphous materials are __ than crystalline materials

more soluble

Amorphous form of a drug will usually be __ __ than crystalline form because there is no crystalline lattice to be broken before the material can dissolve.

amorphous dispersion

which an amorphous drug is stabilized by a polymer or a combination of polymers and/or surfactants.