Anti-infective Agents

Question 1

Germicidal agent

Answer 1

Kills the microorganism

Question 2

Germistatic agent

Answer 2

Prevents the microorganism’s growth

Question 3

Disinfectant

Answer 3

Destroys “bugs” on inanimate objects

Question 4

Antibacterial properties of alcohols

Answer 4

Primary alcohols: antibacterial properties increase with molecular weight (through octanol)
Branching decreases antibacterial properties

Question 5

Phenols

Answer 5

One of the first classes of compounds to be used as a surgical antiseptic
Today, fairly obsolete (skin irritants)
Alkyl, aryl, and halogen substitution increase potency

Question 6

Oxidizing agents

Answer 6

Exert activity through generation of oxygen or oxygen radicals in tissues
Especially effective against anaerobic bacteria
Topical treatments (ex-benzoyl peroxide)

Question 7

Iodine

Answer 7

Inhibits proteins: iodinates aromatic amino acid residues and oxidizes sulfhydryl groups (cysteine)

Question 8

Hypochlorous acid (HClO)

Answer 8

Usually exist as hypochlorite salts

Chlorinates nitrogen atoms in amides and oxidizes sulfhydryl groups in proteins

Question 9

Cationic surfactants

Answer 9

Detergents, which can be used as anti-infectives

Common structural features: quaternary nitrogen atom and long aliphatic tail

Question 10

Preservatives

Answer 10

Compounds added to foods, drugs, and cosmetics that prevent microbial contamination
Typically effective at low concentrations and non-toxic to host

Question 11

2 types of fungal infections

Answer 11

Superficial (ringworm, skin, and nail infections)

Deep-seated (systemic infections)

Question 12

Source of selectivity for targeting fungal infections

Answer 12

Fungi use ergosterol in their lipid bilayers, whereas humans use cholesterol

Question 13

Topical antifungal agents

Answer 13

Fatty acids (resemble natural antifungal on skin)
Phenols and derivatives: interfere with cell membrane integrity and function in fungi

Question 14

Antimetabolites

Answer 14

Drugs that prevent the production or degradation of a normal cellular metabolite

Question 15

Flucytosine

Answer 15

Nucleoside antifungal that is used to treat systemic infections
Converted into 5-fluorouracil in the body, preventing synthesis of thymine (and thus, DNA)

Question 16

2 classes of antifungal antibiotics

Answer 16

Polyenes
Griseofulvin
Natural products: hard to synthesize

Question 17

Allylamine antifungals

Answer 17

Act by interfering with ergosterol biosynthesis: inhibit squalene epoxidase while leaving mammalian enzymes unaffected

Question 18

Azole antifungals

Answer 18

Broadly effective against many topical and systemic infections
At low concentrations, inhibit fungal cell growth (inhibit membrane-bound enzymes)
At high concentrations, kill fungal cells (cause damage to cell membranes)

Question 19

Quinolones

Answer 19

Synthetic antibacterial agents derived from nalidixic acid

Inhibit bacterial DNA synthesis via inhibition of DNA gyrase

Question 20

Quinolone SAR

Answer 20

Must have alkyl group bound to nitrogen
Adding substituents to carbon atom to the right of the nitrogen removes activity
Adding a fluorine at C6 (4 carbons to the left of the nitrogen) increases activity

Question 21

First developed effective systemic agents for bacterial infections

Answer 21

Sulfonamides (sulfa drugs; original drug: prontosil)

Question 22

How sulfonamides work

Answer 22

Inhibition of tetrahydrofolate (THF) coenzyme synthesis from pteridine diphosphate and p-aminobenzoic acid (PABA)

Question 23

Limitations of sulfonamides

Answer 23

Can cause crystalluria (crystallizing in kidney, damaging it)
Have been overprescribed: some bacterial strains are resistant to it (can increase synthesis of PABA, competing with the drug, or can pump the drug out faster than it can enter)

Question 24

Sulfonamide SAR

Answer 24

Aniline ring is necessary for activity (cannot be alkylated)

Sulfonamide portion of molecule (SO2 and amine) is most likely the active structure

Question 25

Trimethoprim

Answer 25

Antibacterial agent: inhibits dihydrofolate reductase (enzyme required for synthesis of tetrahydrofolate coenzyme)

Question 26

Sulfones

Answer 26

Less effective than sulfonamides, but effective in treating leprosy
Dapsone is the only one with appreciable clinical utility