Pharmacology Flashcards
How do alpha-2-agonists work?
These act by stimulating pre-synaptic α2 receptors in the lateral reticular nucleus reducing central sympathetic outflow and in the spinal cord where they augment endogenous opioid release and modulate descending noradrenergic nociceptive pathways
How do oxazolidinones work?
Eg linezolid
Inhibit 50s ribosomal subunit
Gram positive cover incl MRSA and VRE
Aw myelosuppression, thrombocytopenia, peripheral and optic neuropathy, lactic acidosis and MAOI - like effects
How do lincosamides work?
Clindamycin
Acts on 50s ribosomal subunit
Used in necrotising soft tissue infections
Missed aerobic/ anaerobic infections esp in penicillin resistance
Anti- exotoxins effect so used in group a strep infections
How do macrolides work? What are they used for?
Reversibly inhibit 50s ribosomal subunit, prevents ribosome moving along mRNA strand
Eg erythromycin, clarythromycin, azithromycin
Atypical cover
Strep and MSSA
How do aminoglycosides work? What are they used for?
Eg gent and amikacin
Cause insertion of incorrect amino acid, producing false proteins and causing cell death.
Gram negative cover plus enterococcus and MRSA
How do tetracyclines work?
Eg tetracycline - gram positive and negative cover
Oxytetracycline- used for atypicals, ricketsiae and Protozoa
Tigecycline - broad spec but not anti pseudomonal
Reversibly bind to 30s ribosomal subunit
Prevent tRNA binding with mRNA
What is dapsone used for?
Leprosy
Acinomycoses
Toxoplasmosis
What’s co- trimoxazole used for?
PCP
Stenotrophomonas maltophilia
Burkholderia cephacia
How does trimethoprim work?
Inhibits conversion of dihydrofolate to tetrahydrofolate by blocking DHF reductase
THF is an co- enzyme required for the synthesis of DNA and RNA
Used for uncomplicated UTId
Which antibiotics inhibit THF synthesis?
Trimethoprim
Sulphonamides eg co- trimoxazole
Dapsone
How does ciprofloxacin work/ what’s it used for?
Inhibits DNA gyrase and topoisomerase-4 ( DNA synthesis)
Active against Gram negatives, atypicals and some streptococci
How does rifampicin work/ what’s it used for?
Inhibits DNA dependent RNA polymerase
Anti- staphylococcal activity incl MRSA and anti- streptococcal activity
TB and leprosy
Post exposure prophylaxis in neisseria/ haemophilus meningitis
How do nitroimidazoles work?
Eg metronidazole
Inhibit DNA synthesis - form complexes with DNA and cause strand breakage
Activity against anaerobes and Protozoa
What is colistin used for?
Binds to LPS in cell wall of Gram negative organisms
Used for acinetobacter and pseudomonas esp in CF
What cover do glycopeptides have?
Vanc is highly polar and not absorbed from GIT - used in c.diff
Vanc has poor chest penetration ( teicoplanin better)
Aerobic and anaerobic gram positive cover incl MRSA
What is the spectrum of activity of 3rd generation cephalosporins?
Improved Gram negative, reduced gram positive
CNS penetration
Ceftazidime has pseudomonal cover
Eg ceftriaxome, cefotaxime
What is the spectrum of activity of 2nd gen cephalosporins?
Some Gram negative cover eg e.coli, klebsiella
Eg cefuroxime
What is the spectrum of activity of 1st generation cephalosporins?
Eg cephalexin
Gram positive cover
How do cephalosporins work?
Beta-lactam ring as per penicillin
Describe the spectrum of activity of carbapenems
Eg meropenem
Beta- lactamase resistant
Increased Gram negative and anaerobes
May be combined with another drug for improved Gram positive cover
Can be used for ESBL
Emerging resistance of enterococcus (CRE)
No activity against MRSA, atypicals or stenotrophomonas
Describe the spectrum of activity for tazocin
Gram positive
Gram negative
Pseudomonas
First line for HAP/VAP/ neutropenic sepsis
Describe the spectrum of activity for amoxicillin/ augmentin
Improved Gram negative cover
First line for CAP
Clavulanic acid prevents the action of beta- lactamase
What is penicillin active against?
Streptococci
Enterococcus
Neisseria
Spirochetes
How do penicillins work?
Transpeptidase inhibition ( enzyme that forms cross links in cell wall) Beta lactam ring confers anti- transpeptidase activity. Beta-lactamase - producing organisms are penicillin resistant.
What chemotherapy drugs do you know and what are their common side effects?
- Alkylating agents e.g. Cyclophosphamide. Causes DNA cross links preventing replication. Causes idiopathic interstitial pneumonitis, haemorrhagic cystitis
- Anti-metabolites e.g. methotrexate, 5-FU. Diverse mechanism - may interfere with nucleotide metabolism and therefore DNA synthesis and repair. Cause pulmonary fibrosis, nephrotoxicity, cardiotoxicity and acute cerebellar syndrome
- Antibiotics/topoisomerase interactive agents e.g. doxorubicin and bleomycin. Interact with topoisomerase enzymes causing DNA damage. Cause cause cardiotoxicity, pulmonary fibrosis - exposure to high FiO2 causes rapid progression to fibrosis
- Anti-microtubule agents e.g. Paclitaxel and vincristine. Interfere with mitotic and non-mitotic processed. Cause pulmonary and cardiotoxicity and peripheral neuropathy
