Pharmaceutics: Physical Properties Of Drug Molecules

Front 1

Additive Property

Back 1

A property that you can sum up. More of the substance = more of the property.
This is derived from the sum of properties of individual atoms or functional groups within a molecule.
>For instance, mass is an additive property.
>The molecular weight is the sum of masses of each atom in a molecule.
>Likewise volume is an additive property.

Front 2

Constitutive property

Back 2

Property remains the same regardless of how much of a substance you have.
This is derived from the structural arrangement of atoms within a molecule.
>For example, optical rotation is a constitutive property as it depends on the chirality of a molecule.
>Absorption of light, fluorescence etc are examples of constitutive property.
>Color is an example of something that is both additive and constitutive. A substance has a certain color regardless of the amount, but an increase in amount can increase the intensity of that color (ex. dye in solution)

Front 3

Chemical Property

Back 3

Intramolecular and intermolecular interactions of atoms and molecules.

Front 4

Therapeutic Property

Back 4

Drug's effect on the body.
Potency
Strength of Effect
Time in Body

Front 5

Physical Properties

Back 5

Shape
State of Matter
Melting Point
Boiling Point
Mass
Volume
Color
Size

Front 6

Pulmonary Size Requirements

Back 6

To get to the deepest area of the lungs, the optimum particle size range is 1-5 µm
>Bigger: gets stuck further up
>Smaller: particles come back out when you exhale.

Front 7

Particle Size and Tablets

Back 7

Particle size needs to be in a certain range, often paired with a disintegrant, so that it dissolves at a reasonable rate.

Front 8

Rifampin

Back 8

Anti-tubercular medication. Turns bodily excretions a pinkish color.
> Measuring the absorption of light at that color's wavelength using spectrophotometry, say in urine, can tell you how much of the drug is coming out.

Front 9

Absorption

Back 9

Matter absorbs some light, and then transmits (emits) it in a characteristic pattern.
>More concentration = less transmission of light.

Front 10

Absorption is Constitutive

Back 10

If a given substance absorbs spectra around 230 nm, even if you increase the amount, the peak on the readout remains at 230 nm.
>However, the intensity is additive, and this can be used to measure concentrations of substances.

Front 11

Absorption and Emission Spectra

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Absorption and emission spectra can be used to identify a drug molecule.
>Each drug has a characteristic spectrum.
>Characterization techniques which utilize electromagnetic radiation for determination of drug molecules and concentrations are UV/Visible spectrophotometry, HPLC, fluorescence, phosphorescence, infrared spectroscopy, and nuclear magnetic resonance spectroscopy (NMR).

Front 12

Emission

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When matter absorbs light, its electrons are moved into a higher state of energy.
>When they return to their ground state, they emit light. This is called "emission."
S₀ + UV → S* → S₀ + fluorescence
S₀ = ground state
S* = excited state

Front 13

Frequency

Back 13

(ν), is the number of waves passing a fixed point in 1 sec.

Front 14

Wavelength

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(λ), is the extent of single wave of radiation i.e. the distance between two successive maxima or minima.

Front 15

Wave Number

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Inverse of wavelenth, 1/λ.

Front 16

λmax

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The wavelength at which a drug's emission or absorption peak is the highest. (What you set your spectrophotometer to).

Front 17

Light Waves (Spectra)

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Both electric and magnetic fields can be described by sinusoidal waves with characteristic amplitude, A and frequency, ν
>The relationship between frequency and wavelength is:
c = ν x λ
where c = velocity of propagation (speed of light)

Front 18

SAR

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Structure Activity Relationship
>Relationship between the structure of a drug and its therapeutic/toxic effects.
>Test by changing functional groups on a drug, see what substitution effects therapeutic activity and toxicity and which don't.
>Allows beneficial modification

Front 19

Assay

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To determine concentration.

Front 20

Spectrophotometry

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Colorimetric Assay: Can only detect light absorption within the visible light spectrum, wavelength (λ) between 390 µm and 750 µm.
>If the drug does not have a characteristic color, you will have to use UV
>Not always reliable, because multiple drugs might absorb the same wavelength.

Front 21

HPLC

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High Performance Liquid Chromatograph
>HPLC and NMR are better at detecting different compounds that Spectrophotometry, because they can detect very slight differentiations in molecules.

Front 22

Flourescense

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An emission that occurs when the electrons of a substance absorb light and move from the excited state (S*) back to the ground state (S₀).
>Not all drugs fluoresce, but for those that do, their spectra is characteristic.
>Rapid when compared to phosphorescnence (10⁻⁶ to 10⁻⁹ s)
>Emissions must be within the visible range because it can be seen with the naked eye.
>Require a setting of two different λmax. One for its absorption and one for its emission.

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Phosphorescense

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Sometime the electrons enter a third state T*, when they return from this state, they emit light called phosphorescence, which is also characteristic for a given substance.
>Slower than fluorescence, can last from minutes to hours.
>Emissions must be within the visible range because it can be seen with the naked eye.
>Require a setting of two different λmax. One for its absorption and one for its emission.

Front 24

G-protein

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Fluoresces green. Often added to molecules that don't fluoresce as a tag so that they can be detected by fluorescence.
>Green color
>Can show when drugs have gotten into the cell, or where drugs go in the body.