Drugs as Organic Compounds Flashcards
(21 cards)
What is the valency of carbon, and how does this define its bonding in organic molecules?
Carbon has a valency of 4, meaning it can form four covalent bonds. This makes it ideal as the backbone for organic molecules, allowing for diverse structures
Term: Aliphatic compound
A compound consisting of a straight or branched carbon chain (not aromatic) with functional groups attached. The chain is named starting from the carbon bonded to the main functional group
What determines the parent name of an aliphatic organic compound?
The number of carbon atoms in the longest continuous chain (root) determines the parent name
Term: Aromatic compound
Definition: Organic molecules that contain a benzene ring (6 carbon atoms with alternating single and double bonds). When a hydroxyl group is attached, it is called a phenol.
Name the straight-chain alkanes from 1 to 10 carbon atoms.
Methane (1C)
Ethane (2C)
Propane (3C)
Butane (4C)
Pentane (5C)
Hexane (6C)
Heptane (7C)
Octane (8C)
Nonane (9C)
Decane (10C)
What is the correct name for a molecule with a 3-carbon chain, an alcohol group, and a fluorine on carbon 3?
3-fluoropropanol
What does the prefix “di-” or “tri-” signify in organic nomenclature?
These prefixes indicate that more than one identical side chain or substituent group is present (e.g. 1,2-dimethylbenzene).
What is the valency of the following atoms in their uncharged states:
F
Br
O
C
N
Fluorine (F): 1
Bromine (Br): 1
Oxygen (O): 2
Carbon (C): 4
Nitrogen (N): 3
What is Structure-Activity Relationship (SAR)?
SAR describes how the pharmacological activity of a molecule changes when its functional groups are altered.
Give an example of SAR using barbituric acid
Barbituric acid is inactive.
Adding a phenyl group at C5 makes it an anticonvulsant.
Adding an alkyl group (1–5C) makes it hypnotic.
5C in the alkyl group induces convulsant effects.
Replacing the oxygen at C2 with sulfur (oxybarbiturate → thiobarbiturate) increases lipid solubility, enhancing BBB penetration.
What are the structural features of volatile anaesthetics?
They are either ethers or halogenated hydrocarbons
How do halogens affect the potency and stability of volatile anaesthetic agents?
Chloride or bromide: ↑ Potency
Fluoride: ↑ Stability
Ether groups: ↑ Molecular stability
What are the three structural components of a local anaesthetic?
Aromatic group
Intermediate chain
Amine group
How are local anaesthetics classified?
Esters or Amides based on intermediary group:
E: - C(=O),-O-
A: - NH-C(=O)-
What determines the speed of metabolism of a local anaesthetic?
The type of linkage (ester vs. amide) in the intermediate chain.
Esters metabolised faster due to plasma esterases whereas amides metabolised in liver
How is potency and duration of action enhanced in local anaesthetics?
By increasing lipid solubility, achieved through:
Larger side chains on the amine group (e.g. butyl group)
Additions to the aromatic ring (e.g. aminobutyl group)
Why are amine groups considered bases in drug chemistry?
They have a lone pair on nitrogen which can accept a proton (because it has a valency of 3), forming an ammonium ion.
Is phenol a weak or a strong acid
Weak
What happens to midazolam in acidic environments?
The amine group is ionised (protonated), making the molecule water-soluble and buffered.
What structural change occurs in midazolam at physiological pH?
The ring closes to form a non-ionised, lipid-soluble benzodiazepine ring that can cross the BBB.
How does thiopental behave under different pH conditions?
Alkaline pH: Exists as an ionised, water-soluble enol (proton substituted with sodium)
Physiological pH: Undergoes keto-enol tautomerization to become a lipid-soluble, unionised ketone form that can cross the BBB.
