Drug discovery + extraction and sample prep

Question 1

What are the processes used to extract drugs from natural sources?

Answer 1

infusion, decoction, maceration, percolation, continuous hot extraction & counter current

Question 2

Describe the process of infusion

Answer 2

drug stood in hot or cold water for a short time / solid

Question 3

Describe the process of decoction

Answer 3

extraction of soluble constituents by simmering in boiling water for specified time / solid material should be hard and conc not adjusted / thermal degradation

Question 4

Describe the process of maceration

Answer 4

prolonged infusion in aq alcohol in a closed container

Question 5

Describe the process of percolation

Answer 5

maceration then flow of fresh solvent passing over ground material at a specified time

Question 6

What is continuous hot extraction?

Answer 6

uses a soxhlet extractor also called continuous hot percolation , drug extracted using hot solvent

Question 7

What is counter current?

Answer 7

multiple liquid-liquid extractions

Question 8

What does Galenical mean?

Answer 8

medicinal extract or tincture derived from natural sources

Question 9

What does Menstruum mean?

Answer 9

solvent used in extraction

Question 10

What does marc mean?

Answer 10

insoluble materials remaining after extraction

Question 11

What are the types of purification methods available?

Answer 11

SPE/sPME (solid phase) / filtration (solid phase) / chromatography (solid phase) / Separating funnel (immiscible liquid phases) / counter current distribution (immiscible liquid phases) / crystallization (miscible liquid phases) / fractional distillation (miscible liquid phases)

Question 12

What do acid base extractions require?

Answer 12

pH change of aq phase

Question 13

What are the methods used to separate drugs from miscible phases?

Answer 13

rotary evaporation (vacuum & heat) / fractional distillation / fractional crystallization (based on solubility) / sublimation/ lyophilisation (freeze drying, solid to gas using lyophiliser)

Question 14

What are the key stages of a drug discovery project?

Answer 14

target identification / hit or lead identification / lead optimisation / pre-clinical development / clinical development phase 1,2,3

Question 15

What is a hit?

Answer 15

a compound with biological activity in a basic model

Question 16

What is a lead?

Answer 16

a compound with biological activity in in vitro models

Question 17

What is a candidate?

Answer 17

a compound with an overall profile consistent with target product profile

Question 18

What is LogD and how is it calculated?

Answer 18

same as LogP apparent / D = conc of drug in Octanol/conc in water / should always be quoted with pH 7.4

Question 19

What is LogP?

Answer 19

a measure of lipophillicity in a compound, its partition coefficient between and organic and an aq solvent. P = conc of drug in Octanol/ conc of unionised drug in water

Question 20

What’s significant about the logD value of neutral drugs?

Answer 20

It’s the same as its logP value

Question 21

For ionisable drugs how does their logD value relate to logP?

Answer 21

LogD is less than or equal to logP

Question 22

What does an increase in logD result in and why is it important?

Answer 22

it will cause an increase in potency and permeability / decrease in solubility ,metabolism, protein bonding and toxicity therefore its ability to affect other factors makes it important