Pharmacology Flashcards
Mechanism of statins
- Lipid/cholesterol lowering agents
- Inhibit HMG-coA reductase which plays a role in cholesterol production
- Increases LDL (bad cholesterol) uptake by the liver
Mechanism of fibrates
- Lipid/cholesterol lowering agents
- Activate PPAR
- Induces transcription of genes that facilitate lipid metabolism
- Increases HDL levels (good cholesterol)
Class and mechanism of penicillin
- Broad spectrum, bactericidal beta-lactam
- Inhibit bacterial cell wall synthesis by preventing cross linking of peptides by binding to the transpeptidase enzyme (PBPs), preventing bacterial cell wall formation
- Cell walls are improperly made, this allows water to flow into the cell, causing it to burst (cytolysis)
Different examples of macrolides
Macrolides are a class of antibiotic that includes erythromycin, roxithromycin, azithromycin and clarithromycin
- Used for patients with penicillin allergy
First-line indications for macrolides
First-line indications for macrolides include the treatment of atypical community acquired pneumonia, H. Pylori (as part of triple therapy), chlamydia and acute non-specific urethritis.
Cephalosporin class?
Beta lactam, bactericidal
Mechanism of cephalosporin
- Mimic the D-Ala-D-Ala site, irreversibly inhibiting the PBP cross-linking of the peptidoglycan bacterial cell wall
Indications of cephalosporin
Septicaemia Pneumonia Meningitis Biliary-tract infections Peritonitis Urinary-tract infections
Examples of nucleoside reverse transcriptase inhibitors
Abacavir
Tenofovir
Emtricitabine
Mechanism of nucleoside reverse transcriptase inhibitors
Stop HIV changing ssRNA to dsDNA
- They cause chain termination after they have been incorporated into DNA
Examples of NNRTIs
Nevirapine
Efavirenz
Etravirine
Mechanism of NNRTIs
Stop HIV from changing ssRNA into dsDNA
- They have a high affinity for the hydrophobic binding pocked located near the active site of HIV reverse transcriptase, so it cannot catalyse DNA polymerisation
Mechanism of protease inhibitors
Block new HIV from being cut into smaller pieces and from being reassembled into new, infectious particles
- Mimic the natural peptide substrate of HIV called aspartyl protease enzyme
Mechanism of integrase inhibitors
Block HIV from being integrated into the cell DNA
- They target HIV integrase, responsible for the integration of viral genetic material into human DNA, a crucial step in the replication cycle of HIV
Mechanism of entry inhibitors
CCR5 antagonists
- Bind to CCR5 receptor which blocks HIV protein gp120 from association with the receptor, so it is unable to enter human macrophages and T cells, but it can use CXCR4 instead
Mechanism of attachment and post-attachment inhibitors
- Bind to the gp120 portion of HIV envelope protein that makes up the spikes of the virus
- Prevents HIV from attaching to CD4 receptor on T cells, which it uses to gain entry to the cell plasma membrane
Class and mechanism of clotrimazole
Anti fungal - lanosine demethylase inhibitor
Inhibition of yeast 14-alphademethylase, a cytochrome p450 enzyme which converts lanosterol to ergosterol, an important component of the fungal cell membrane
- Causes increased membrane permeability and possibly disruption of membrane bound enzymes
Class and mechanism of fluconazole
- Lanosine demethylase inhibitor
- Anti-fungal
- Inhibits 14-alpha-demethylase, a cytochrome p450 enzyme which converts lanosterol into ergosterol, an important component of the fungal cell membrane
Class and mechanism of nystatin
- Ionophore
- Anti-fungal
- Binds ergosterol in fungal cell membranes, causes formation of pores in the membrane, leading to potassium and other cellular constituents leakage, causing cell death
Class and mechanism of Amphotericin
- Ionophore
- Binds ergosterol in fungal cell membranes
- Pore formation in membrane
- Leakage of contents, e.g. K+ and other constituents
- Cell death
Class and mechanism of betamethasone & clobetasone
- Glucocorticoid receptor agonist
- Anti-inflammatory, anti-pruritic and vasoconstrictive properties
- Binds to receptor, which then translocates to the nucleus and binds to glucocorticoid response elements, causing the increase or decrease of specific target genes, having anti-inflammatory actions:
1. Induction of lipocortin-1 synthesis
2. Cox-1 and Cox-2 expression is suppressed, decreasing eicosanoid production
Class and mechanism of imatinib
- Tyrosine kinase inhibitor
- Targets the Bcr-Abl tyrosine kinase (oncoprotein - CML)
- Inhibits cell proliferation driven by Bcr-Abl positive cells
- Induces apoptosis
Class and mechanism of dacarbazine & cyclophosphamide
- Which stage of the cell cycle does it act on
- Alkylating agent (chemotherapy)
- Bind covalently to DNA via their alkyl group to guanine, preventing the strands from linking as they should
- Causes the breakage of DNA strands and then death of the cancer cell as it cannot multiply
- CELL CYCLE INDEPENDENT - works at any point
Class and mechanism of vinblastine
- Anti-microtubule agent
- Block cell division by preventing microtubule function
- Prevents cancer cells from completing mitosis, leading to apoptosis
Class and mechanism of etoposide
- Which stage of the cell cycle does it act on
- DNA topoisomerase II inhibitor
- Inhibits DNA topo II, thereby inhibiting DNA re-ligation
- Causing errors in DNA synthesis, leading to apoptosis
- S and G2
Class and mechanism of 5-fluorouracil
- Which stage of the cell cycle does it act on
- Anti-metabolite
- Pyrimidine analogue
- Anti-metabolites masquerade as purine or pyrimidine and become incorporated into DNA.
- Acts on the S phase of the cell cycle, stopping normal development and division
Ciprofloxacin class and mechanism
- Quinolone = topo II inhibitor
- Inhibits topo II (DNA gyrase) which are required for bacterial DNA replication, transcription, repair, strand supercoiling repair, and recombination
Class and mechanism of vancomycin
- DRUG OF LAST RESORT
- Not active against gram-negative bacilli, mycobacteria or fungi
- Inhibition of NAM-NAG peptide subunits into the peptidoglycan matrix, which is a major structural component of the Gram-positive cell walls
Class and mechanism of sulfamethoxazole.
- Indications
- PABA analogue
- Competes with PABA in binding to dihydrofolate synthetase
- Inhibition of dihydrofolate synthetase will inhibit the synthesis of tetrahydrofolic acid (THF)
- THF is required for the synthesis of purines and dTMP
- Inhibition of THF synthesis inhibits bacterial growth
- Similar to trimethoprim
- Indications: bronchitis, prostatitis, UTIs
Class and mechanism of trimethoprim
- Used for UTI and acute/chronic bronchitis
- Folate antagonist
- Binds to dihydrofolate reductase, inhibiting the reduction of dihydrofolic acid to tetrahydrofolic acid
- THF is an essential precursor in the thymidine synthesis pathway and therefore inhibition of this will inhibit bacterial DNA synthesis
Class and mechanism of rifampicin
Broad spectrum anti-biotic - RNA/DNA polymerase inhibitor
- Antimycobacterial
- Its mode of action is via the inhibition of DNA-dependent RNA polymerase, leading to a suppression of RNA synthesis and cell death
Class and mechanism of gentamicin
- Aminoglycoside antibiotic
- 30S/50S inhibitor
- Broad-spectrum
- Bind to bacterial 30S ribosomal subunit, inhibiting protein synthesis
- Treat TB and gram-positive infections
- Can cause significant ear and kidney damage
Class and mechanism of erythromycin
- Indications
- Macrolide antibiotic
- 50S inhibitor
- Reversibly binds 50S subunit of bacterial ribosomes at the donor binding site, blocking the translocation of peptides from the acceptor site to the donor site, inhibiting protein synthesis
- Respiratory infections
- Syphillis
- Skin infections
- Chronic prostatitis
- ONLY EFFECTIVE AGAINST DIVIDING ORGANISMS
Class and mechanism of oxytetracycline
- Broad spectrum antibiotic - 30S inhibitor
- Mechanism: inhibition of bacterial cell wall growth by binding to the 30S ribosomal subunit. Preventing amino-acyl tRNA from binding to the A site of the ribosome, causing inhibition of translation
Class and mechanism of benzylpenicillin / penicillin G
- Transpeptidase inhibitor
- Use for gram-positive organisms
- Binds to PBP, causing the inhibition of bacterial cell wall synthesis