Controlled Substances

Partitioning

Occurs at a phase boundary (solid, liquid, gas) and is a function of pressure and temperature

Why is partitioning important?

Allows chromatography to work

Equilibrium

the state where the concentration of all reactants and products remains constant with time

Le Chatelier’s Principle

Disturbance of equilibrium results in a counteraction to reestablish equilibrium

How are pKa and Ka related?

pKa is the exponent of a Ka value, so the smaller the pKa, the more products you have

Why is lipophilicity important?

solubility of a drug through lipid membranes-where the drug will be absorbed

Equation for lipophilicity

LogP=log[Aorg]/[Aaq] where a positive value indicates lipophilicity

What is LogD?

The distribution coefficient, represents the partition coefficient for both the neutral and ionized for of the compound at any pH

Describe the Strength of an Acid

a molecules tendency to donate an electron

What is pH really a measure of?

Amount of free H+ or OH- in solution

pH= to what

-[logH+]

pOH= to what

-log[OH-] or Kw-pH

Common acidic groups

phenolic or carboxylic acid

Common basic groups

Amino groups

Henderson-Hasselbalch equation

pH/OH=pKa/b + log[conjugate form/natural form]

When is equilibrium completely one sided?

when a concentration is 100 times on one side (corresponds to 2 pH units)

Order the digestive tract from most to least acidic

stomach (1-3), small intestine(5-7), colon(7-8)

When will a drug absorb in the digestive tract?

Where it is most least polar as that makes it better able to cross cell barriers into the blood stream

What is the isoelectric (pI) point?

The average pKa of all the acidic/basic centers in a molecule and where the molecule is neutral

Dry extraction

The most simplistic extraction, add an organic solvent to a powder. This allows the extraction of drugs from common diluents

Liquid-Liquid extraction

AKA solvent extraction. Separates molecules based on pH dependence between an aqueous and organic layer. Solvents must be immiscible and density is an important consideration

Liquid-Liquid extraction advantages

Quick and easy for qualitative analysis, and has a high capacity for eluants and high selectivity.

liquid-Liquid extraction disadvantages

Large solvent consumption, emulsions possible, and includes bulky and expensive glassware

Liquid-Liquid micro extraction

Same principle as a liquid-liquid extraction but on a much smaller scale (solvent volumes<5mL)

Solid-Phase Extraction

Includes dissolved analyses from the solution and the affinity of a solute for sorbent material relative to solution. (essentially a column)

What is Kd in solid-phase partitioning?

Expresses the degree of interaction =[stationary]/[mobile]

Normal phase in SPE

polar stationary phase, non polar solvent (elute with polar solvent)

Reversed phase in SPE

Non-polar stationary phase, polar solvent (elute with non polar solvent)

Ion exchange in SPE

Anion (positively charged stationary phase) and cation (negatively charged stationary phase)

SPE General Process

1. Condition the sorbent material

2. Load the sample solution

3. Wash the sorbent material

4. Elute analyses from sorbent material

How does SPE elution strength change as the elution continues?

It increases in strength, making is more likely to elute whatever analyses are left in the column

One SPE concern

Binding capacity of stationary phase determines volume of solution

SPE advantages

Enhanced separation compared to LLE, greater recovery, reduced organic solvent waste, less apparatus required

SPE disadvantages

More complex chemistry, requires method development, more steps in the extraction process, cost of SPE equipment

Solid-Phase Microextraction (SPME)

Fiber coated with extracting phrase, targets volatile and semi-volatile compounds. The sample is heated and allowed to reach equilibrium between the headspace and the solution

SPME advantages

Targes colatile and semi-volatile compounds, preconcentration step, automation

SPME disadvantages

Lower effectiveness (reduced surface area), requires method optimization, only limited commercially available chemistries

Define Drug

Substance capable of physiological change

Name the five methods of drug classification

origin, effect, chemistry, use, and scheduling (potential for abuse)

Three ways to classify drugs by origin

natural product, semi-synthetic, synthetic

Name the 7 potential effects of drugs

CNS depressant/stimulant, hallucinogens, dissociative anesthetics, narcotic analgesics, inhalants, cannabis

CNS Depressants

Slow down the operation of the brain/body (slow heartbeat, lower blood pressure, reduced anxiety)

CNS stimulant

Speed up/overstimulate the body, accelerated heart rate and elevated blood pressure.

Hallucinogens

Cause the user to have an altered perception of reality

Dissociative anesthetics

Inhibit pain by dissociating the brain’s perception of pain

narcotic analgesics

relieve pain, induce euphoria, and create mood changes

inhalants

Breathable substances that produce mind altering results and effects

Cannabis

Marijuanna

Chemical classification categories

acid/base character, salt vs freebase, similarity in structure, functional groups

Use classification categories

Predator, club, and performance-enhancing

What is scheduling based on?

Accepted medical use, potential for abuse, safety/dependence liability

Variants of cannabis

Sativa, Indica, ruderalis

Main component of marijuana

delta 9 THC

Difference between male and female cannabis plants

males are harvest for hemp and females for the THC content

Ways to collect resin from marijuana plants

Hand rubbing, shaking, sieving, water extraction, tumbling

Effects of marijuana

Euphoria, relaxation, distortions of sensory perceptions, increase in appetite, anxiety, fear, panic

How does the federal farm bill differentiate Marijuana from hemp?

Hemp is a cannabis plant with <0.3% delta 9 THC concentration

How is the potency trend for cannabis changing?

It is increasing

Describe the macroscopic morphology of a cannabis plant

Serrated palmate leaves, grooved stems, tortoise shell patterned seeds with a ridge

List the three types of trichomes on a cannabis plant

Cystolic hairs (bear claw), glandular hairs, cover hairs (long and thing)