Drugs List Block 9 Flashcards
Paracetamol
- It indirectly inhibits COX, which is ineffective in the presence of peroxides. This could explain why it does not work well within platelets.
- It inhibits COX-3. This enzyme is not well undertood.
- Its antipyretic effects are due to effects on the hypothalamus, resulting in peripheral vasodilation and sweating.
Amoxicillin
Amoxicillin is active against a wide range of Gram-positive, and a limited range of Gram-negative organisms. Amoxicillin binds to penicillin-binding protein 1A (PBP-1A) located inside the bacterial cell well. This inactivation of PBP-1A prevents the cross-linking of two linear peptidoglycan strands, inhibiting bacterial cell wall synthesis. Cell lysis is then mediated by bacterial cell wall autolytic enzymes such as autolysins. Amoxicillin can be combined with clavulanic acid, a β-lactamase inhibitor, to overcome bacterial antibiotic resistance mediated through β-lactamase production.
Methicillin
Meticillin is a narrow spectrum beta-lactam antibiotic. It is largely replaced by flucloxacillin and dicloxacillin
inhibits bacterial cell wall synthesis, via inhibition of transpeptidase enzyme used by bacteria to cross-link the peptide (D-alanyl-alanine) used in peptidogylcan synthesis
Cefuroxime
bactericidal, highly active against gram-negative cocci and bacilli,
Its mechanism of action is similar to penicillin, and so it inhibits cell wall synthesis, leading to bacterial lysis.
Cefuroxime can cross the blood brain barrier.
Benzylpenicillin
Penicillin G is a beta-lactam antibiotic used to target usually gram-positive organisms. But has been shown in vitro to target gram-negative aerobic and anaerobic bacteria in addition.
inhibition of cell wall synthesis. In addition it may inhibit the action of bacterial autolysin inhibitor. Penicillin G is stable against hydrolysis by a variety of beta-lactamases, including penicillinases, and cephalosporinases and extended spectrum beta-lactamases
Oxytetracycline
Oxytetracycline is known as a broad-spectrum antibiotic. It is used to treat many infections, including acne.
The mechanism of action of Oxytetracycline is the inhibition of bacterial cell growth by binding to the 30S ribosomal subunit.
Oxytetracycline is lipophilic and therefore can pass through the cell membrane or passively diffuse through porin channels in the bacterial membrane.
Erythromycin
Erythromycin is used to treat multiple infections, including respiratory infections, syphillis, skin infections, etc but is effective only against actively dividing organisms.
Macrolide.
reversibly binds to the 50 S subunit of bacterial ribosomes, at the donor binding site. This binding blocks the translocation of peptides from the acceptor site to the donor site, inhbiting protein synthesis.
After absorption, erythromycin diffuses readily into most body fluids, and will pass into both breast milk, and across the placental barrier.
Gentamicin
broad spectrum aminoglycoside antibiotic, useful for infections involving Gram-negative bacteria, such as Pseudomonas, Acinetobacter, and Enterobacter. Aminoglycosides bind to the bacterial 30S ribosomal subunit, inhibiting protein synthesis. However, aminoglycosides can be used to treat mycobacteria (TB) and gram positive infections.
However, aminoglycosides can cause significant ear and kidney damage.
30s and 50s inhibitor
Rifampicin
Rifampicin is a broad spectrum antibiotic (targets both gram-positive and gram-negative organisms)
inhibits DNA-dependent RNA polymerase, leading to a suppression of RNA synthesis and cell death. Importantly Rifampicin can target bacterial but not mammalian versions of the enzyme. Due to the emergence of resistant bacteria, the use of Rifampicin is restricted to mainly mycobacterial infections.
Rifampin is metabolized in the liver and eliminated mainly in bile and, to a limited extent, in urine.
Trimethoprim
Trimethoprim is used to treat urinary-tract infections, acute and chronic bronchitis.
binds to dihydrofolate reductase inhibiting the reduction of dihydrofolic acid to tetrahydrofolic acid (THF).
Folate antagonist
Sulfamethoxazole
Sulfamethoxazole is used to treat bronchitis, prostatitis and urinary tract infections.
It competes with para-aminobenzoic acid (PABA) in binding to dihydrofolate synthesase. It can therefore cause the inhibition of dihydrofolate synthetase, inhibiting the synthesis of tetrahydrofolic acid (THF) synthesis. THF is required for the synthesis of purines and dTMP and inhibition of its synthesis inhibits bacterial growth.
Trimethoprim and sulfamethoxazole are commonly used in combination as they target the same pathway and their synergistic effects reduce the development of bacterial resistance.
Sulfonamide
Paba analogue
Vancomycin
Vancomycin is often reserved as the “drug of last resort”, used only after other antibiotics have failed, and is active against Listeria monocytogenes, Streptococcus pyogenes, Streptococcus pneumoniae (including penicillin-resistant strains), Streptococcus agalactiae, Actinomyces species, and Lactobacillus species.
Vancomycin is not active in vitro against gram-negative bacilli, mycobacteria, or fungi.
inhibition of incorporation of N-acetylmuramic acid (NAM)- and N-acetylglucosamine (NAG)-peptide subunits into the peptidoglycan matrix; which forms the major structural component of Gram-positive cell walls. (Peptidoglycan inhibitor)
In addition, vancomycin alters bacterial-cell-membrane permeability and RNA synthesis.
Colistin
Colistin is used to treat acute or chronic infections due to sensitive strains of certain gram-negative bacilli, particularly Pseudomonas aeruginosa.
disrupts the bacterial cell membrane, changing its permeability.
In addition colistins can enter the bacteria and precipiate cytoplasmic compnoents, mainly ribosomes.
Polymyxins were largely superceded by extended-spectrum penicillins and cephalosporins. However, the emergence of multidrug-resistant gram-negative bacteria, have led to the revived use of the polymyxins.
Ciprofloxacin
Gram +-
inhibition of topoisomerase II (DNA gyrase) and topoisomerase IV, which are required for bacterial DNA replication, transcription, repair, etc
Topoisomerase II inhibitor
Fusidic acid
Fusidic acid is a bacteriostatic antibiotic typically used in creams and eyedrops. inhbits the translocation of the elongation factor G (EF-G) from the ribosome, leading to inhbition of protein synthesis. In addition it also can inhibit chloramphenicol acetyltransferase enzymes.
Translocation inhibitor
Ibuprofen
Reversible COX enzyme inhibitor
inhibition of (COX-2) which decreases the synthesis of prostaglandins involved in mediating inflammation, pain, fever and swelling.
The antipyretic effects may be due to action on the hypothalamus,
Aspirin
The analgesic, antipyretic, and anti-inflammatory effects of acetylsalicylic acid are due to actions by both the acetyl and the salicylate portions of the intact molecule as well as by the active salicylate metabolite.
Acetylsalicylic acid directly and irreversibly inhibits the activity of both types of cyclooxygenase (COX-1 and COX-2) to decrease the formation of precursors of prostaglandins and thromboxanes from arachidonic acid.
Irreversible inhibition of COX prevents the formation of the aggregating agent thromboxane A2 in platelets. Platelets cannot produce more COX enzyme and thus, the effects of aspirin persist for the life of the exposed platelets (7-10 days).
Aciclovir
Aciclovir is an antiviral agent activated by viral thymidine kinase. Aciclovir triphosphate competitively inhibits viral DNA polymerase. Once incorporated into DNA, aciclovir acts as a termination signal.
Aciclovir is selective and low in cytotoxicity as the cellular thymidine kinase of normal, uninfected cells does not use aciclovir effectively as a substrate.
DNA polymerase inhibitor
Amantadine
Viral ion channel disruptor
Amantadine is
1) an antiviral drug
2) an antiparkinson agent, (usually combined with L-DOPA).
The mechanism of action against virus infection is the inhibition of a viral protein, M2 (an ion channel), which is needed for the viral particle to become “uncoated” once it is taken inside the cell by endocytosis.
Diamorphine
Heroin is a mu-opioid agonist. Heroin, targets four endogenous neurotransmitters (beta-endorphin, dynorphin, leu-enkephalin, and met-enkephalin). Heroin reduces (and sometimes stops) production of the endogenous opioids.
The onset of heroin’s effects is dependent on the method of administration. Taken orally, heroin is totally metabolized in vivo into morphine before crossing the blood-brain barrier; so the effects are the same as oral morphine. Taken by injection, heroin crosses into the brain, where it is rapidly metabolized into morphine by removal of the acetyl groups. It is the morphine molecule that then binds with opioid receptors and produces the subjective effects of the heroin high.
morphine more common in clinical practice.
Amprenavir
Amprenavir is a protease inhibitor used to treat HIV-1. Its mechanims of action is to inhibit HIV-1 protease, which is required for the proteolytic cleavage of the viral polyprotein precursors into the individual functional proteins found in infectious HIV-1. This inhibition of the protein cleavage results in the formation of immature non-infectious viral particles. Protease inhibitors are generally used in combination with other anti-HIV drugs.
