Pharmacology Quiz on Antibiotics and Mechanisms

A class of synthetic antibiotics with a unique structure involving a pyridone ring fused to another aromatic ring.

The most common quinolone drugs end with the suffix '-floxacin'.

Quinolones are effective against a wide range of bacteria, including those causing urinary tract infections (UTIs), skin infections, and respiratory tract infections (RTIs).

Quinolones are available both for oral and intravenous administration.

A class of antibiotics that disrupt the synthesis of nucleic acids (DNA and RNA).

A group of antibiotics that disrupt the synthesis of important molecules needed for bacterial growth.

Antibiotics that damage or disrupt the bacterial cell membrane, leading to leakage of essential components and cell death.

A class of antibiotics that inhibit the synthesis of cell walls, essential for bacterial survival.

A chemical group that enhances the activity of a drug, commonly found at the C5 position in quinolone antibiotics. It contributes to the drug's effectiveness without increasing phototoxicity.

A chemical modification that improves the pharmacokinetic properties of quinolones, often present at the C6 position.

The presence of an aromatic ring is essential for the activity of quinolones, but the ring can have optional nitrogen atoms.

Substitution at specific positions like C5, 6, 7, and 8 on the quinoline structure usually enhances the antibiotic's activity.

A chemical group that improves the activity and broadens the spectrum of quinolones, commonly found at the C7 position.

Alkyl groups, such as methyl, ethyl, and cyclopropyl, have an impact on the activity of quinolones, with larger groups generally providing more activity.

Aryl groups can also attach to quinolones and lead to active compounds, a common example being the 2,4-difluorophenyl group.

Ring condensation in quinolones, such as between positions 1 and 8, generally increases activity and prolongs the duration of the drug's effects.

Rifamycins are a class of antibiotics that target bacterial RNA polymerase. They work by binding to a specific peptide chain unique to bacterial RNA polymerase, preventing the initiation of transcription. Rifamycins are particularly effective against Gram-positive bacteria, including Mycobacterium tuberculosis, making them a key treatment for tuberculosis.

Metronidazole is an effective antimicrobial drug used to treat different infections, particularly amebiasis and anaerobic infections. Once inside the cell, Metronidazole works by converting its nitro group to a nitroso group through a process called nitro reduction. This process ultimately produces harmful free radicals that attack and fragment the DNA of the target bacteria.

Polymyxin B is a potent antibiotic that targets bacterial cell membranes. It effectively disrupts the integrity of the membrane by binding to it, leading to leakage of vital molecules like nucleosides. This process alters cellular permeability and causes cell death.

Nitrofurans are a group of antibiotics that showcase a broader spectrum of activity than nitroimidazoles. This group is known for having a low incidence of resistance. Their primary action is similar to metronidazole, involving the reduction of the nitro group to form damaging free radicals that disrupt bacterial DNA.

Nitrofurantoin is a commonly used antibiotic in the Nitrofurans group. It's usually effective against both Gram-positive and Gram-negative bacteria, making it a suitable treatment for urinary tract infections (UTIs). Nifuroxazide, another member of the Nitrofurans group, is primarily used to target colitis and diarrhea.

Sulfadiazine, Sulfamethoxazole, and Suladoxine are examples of sulfonamides that work in the body. Their effects last for an intermediate amount of time.

Sulfonamides are commonly used to fight urinary tract infections (UTIs).

Sulfonamides can be combined with trimethoprim to create a potent antibiotic called cotrimoxazole.

These drugs block the enzyme dihydrofolate reductase (DHFR), which is crucial for bacterial DNA synthesis.

Sulfadoxine, a long-acting sulfonamide, is often used for malaria treatment.

Sulfasalazine, a prodrug, splits into 5-amino Salicylic Acid (5-ASA) and Sulfapyridine in the body. 5-ASA has anti-inflammatory properties, while Sulfapyridine is antibacterial, making it effective for treating ulcerative colitis and bacterial diarrhea.

Silver Sulfadiazine cream is used on wounds and burns, while Sulfacetamide eye drops treat eye infections like conjunctivitis.

Trimethoprim, another important antibiotic, inhibits DHFR in bacteria and, therefore, DNA synthesis. It is highly selective for bacterial DHFR, meaning it has a much greater effect on bacteria.

Sulfonamides are a class of antibiotics that inhibit the synthesis of dihydrofolic acid (DHFA), a crucial coenzyme for bacterial growth. They achieve this by mimicking para-aminobenzoic acid (PABA), a key substrate for DHFA synthesis.

Sulfonamides are selectively toxic to bacteria, meaning they primarily target bacterial cells without significantly affecting human cells. This is because humans obtain folic acid from their diet, unlike bacteria which synthesize it.

Sulfonamides are typically bacteriostatic, meaning they inhibit bacterial growth without directly killing them. They achieve this by blocking the first step in the folic acid synthesis pathway, leading to an interruption in DNA and RNA synthesis, ultimately halting bacterial growth.

Sulfonamides exhibit a synergistic effect when combined with folate reductase inhibitors like trimethoprim. This combination blocks the biosynthesis of folic acid at multiple steps, resulting in a broader antibacterial spectrum and a reduced likelihood of developing resistance.

Prontosil, the original sulfonamide, was inactive in vitro but activated in vivo. This is because it was a prodrug, meaning it was metabolized in the body to its active form, sulfanilamide.

The structure-activity relationship of sulfonamides indicates that the aromatic ring, sulfonamide group, and para-amino group are crucial for activity. Modifications to these parts can lead to inactivity.

The para-amino group of sulfonamides is essential for their activity and acts as the electron-withdrawing group (EWG) required for activity. Modifications to other positions on the aromatic ring can render the molecule inactive.

Sulfonamides with a primary or secondary amine group attached to the sulfonamide group are active, while those with a tertiary amine are inactive. This indicates the importance of the nitrogen atom and its substituents.