First Aid USMLE Step 1: Pharmacology (Complete)All the drugs from every section of First Aid and maybe some extra from UWorld ★ = 1st line drug

Penicillin G (IV and IM) Penicillin M (oral) *MOA:* *β-lactam*: a structural analog of D-ala-D-ala (a normal component of cell walls) which binds and inactivates bacterial transpeptidases (penicillin-binding protein, PBPs) to block peptidoglycan cross linking *Clinical use:* Bactericidal for Gram-⊕ cocci/rods, Gram-⊖ cocci (Neisseria), and spirochetes Mostly used for Gram-⊕ organisms (S. pneumoniae, S. pyogenes, Actinomyces). Also used for Gram-⊖ cocci (mainly N. meningitidis) and spirochetes (namely T. pallidum). Bactericidal for Gram-⊕ cocci, Gram-⊕ rods, Gram-⊖ cocci, and spirochetes. Penicillinase sensitive. *Toxicity:* Hypersensitivity reactions (type II), hemolytic anemia *MOR:* Penicilinase (a type of β-lactamase) in bacteria cleaves Oxacillin Nafcillin Dicloxacillin Penicillinase-resistant penicillins *MOA:* Same as penicillin. *Narrow spectrum*; penicillinase resistant because bulky R group blocks access of β-lactamase to β-lactam ring. *Clinical use:* Bactericidal, narrow spectrum: *S. aureus* (except MRSA; resistant due to altered penicillin-binding protein target site). *Toxicity:* Hypersensitivity reactions (type II), interstitial nephritis "Use *naf* (*naf*cillin) for staph." Nafcillin has penetration to CNS 00:10 01:26 Aminopenicillins: Ampicillin Amoxicillin Penicillinase-sensitive penicillins *MOA:* Same as penicillin. Wider spectrum with better activity against Gram-⊖ bugs; penicillinase sensitive. Administer with clavulanic acid to protect against destruction by β-lactamase. *Clinical use:* Bactericidal for Gram-⊕ cocci/rods, Gram-⊖ cocci, spirochetes; Extended-spectrum penicillin: *H.* influenzae, *H.* pylori, *E.* coli, *L*isteria monocytogenes, *P*roteus mirabilis, *S*almonella, *S*higella, enterococci. *HHELPSS* *Toxicity:* Hypersensitivity reactions (type II), ampicillin rash (often with EBV infection- reaction-not an allergy), pseudomembranous colitis *MOR:* β-lactamase activity Ticarcillin Piperacillin Ureidopenicillins: "Antipseudomonals" *MOA:* Same as penicillin. Extended spectrum. *Clinical use:* *Pseudomonas spp.* and Gram-⊖ rods Hospital-acquired pneumonias (Klebsiella, H. influenzae, Enterobacter) Susceptible to penicillinase; use with β-lactamase inhibitors. *Toxicity:* Hypersensitivity reactions (type II) Clavulanic Acid Sulbactam Tazobactam *MOA:* β-lactamase inhibitors *Clinical use:* Often added to penicillin antibiotics (aminopenicillins, antipseudomonals) to protect the antibiotic from destruction by β-lactamase (penicillinase). "*CAST*" - *C*lavulanic *A*cid, *S*ulbactam, *T*azobactam Cefadroxil Cephalexin Cephradine (PO) Cefazolin (IV) Cefazolin Cephalexin *1st Generation Cephalosporins* *MOA:* Same as that of penicillins *Clinical use:* Gram-⊕ cocci: streptococci, methicillin-susceptible staphylococci Community-acquired strains of enteric Gram-⊖ rods, *P*roteus spp., *E. c*oli, *K*lebsiella spp. (*PEcK*) Cefazolin: used prior to surgery to prevent S. aureus wound infections. *Toxicity:* Hypersensitivity reactions, autoimmune hemolytic anemia, disulfiram-like reaction, vitamin K deficiency. Exhibit cross-reactivity with penicillins. Potentiate the nephrotoxicity of aminoglycosides. *MOR:* Structural change in penicillin-binding proteins (transpeptidases). All cephalosporins are typically inactive against *L*isteria monocytogenes, *A*typical pneumonias (Chlamydia, Mycoplamsa), *M*RSA, and *E*nterococci. (*LAME*) Cefaclor (PO) Cefuroxime (PO) Cefoxitin (IV) *2nd Generation Cephalosporins* *MOA:* Same as that of penicillins *Clinical use:* Less activity than 1st generation against Gram-⊕ cocci, though enough be useful; more activity against enteric Gram-⊖ rods *Cefuroxime & cefaclor:* Haemophilus influenzae and Neisseria meningitides *Cefoxitin:* very active against enteric anaerobes (Bacteroides & Prevotella spps.) *HEN PEcKS* *H*aemophilus influenzae, *E*nterobacter aerogenes, *N*eisseria spp., *P*roteus mirabilis, *E. c*oli, *K*lebsiella, *S*erratia marcescens. *Toxicity:* Hypersensitivity reactions, autoimmune hemolytic anemia, disulfiram-like reaction, vitamin K deficiency. Exhibit cross-reactivity with penicillins. Potentiate the nephrotoxicity of aminoglycosides. *MOR:* Structural change in penicillin-binding proteins (transpeptidases). All cephalosporins are typically inactive against *L*isteria monocytogenes, *A*typical pneumonias (Chlamydia, Mycoplamsa), *M*RSA, and *E*nterococci. (*LAME*) *Ceftriaxone* Cefotaxime Ceftazidime Cefixime Cefpodoxime Loracarbef (PO) *3rd Generation Cephalosporins* *MOA:* Same as that of penicillins *Clinical use:* Serious Gram-⊖ infections resistant to other β-lactams. More activity against nosocomial Gram-⊖ bacilli, like Enterobacter spp., Citrobacter spp., and Serratia marcescens *Ceftriaxone:* Neisseria spp., disseminated Lyme disease, anthrax, H. influenzae meningitis, S. typhi *Ceftazidime:* some activity against Pseudomonas spp. but less against Gram-⊕ cocci; the opposite is true for ceftriaxone, cefotaxime, and the oral 3rd generation drugs *Toxicity:* Hypersensitivity reactions, autoimmune hemolytic anemia, disulfiram-like reaction, vitamin K deficiency. Exhibit cross-reactivity with penicillins. Potentiate the nephrotoxicity of aminoglycosides. *MOR:* Structural change in penicillin-binding proteins (transpeptidases). All cephalosporins are typically inactive against *L*isteria monocytogenes, *A*typical pneumonias (Chlamydia, Mycoplamsa), *M*RSA, and *E*nterococci. (*LAME*) Cefepime *4th Generation Cephalosporins* *MOA:* Same as that of penicillins. Binds PBP 2z, which is produced by MRSA strains *Clinical use:* Combines the features of 3rd generation cephalosporins broad activity against streptococci, methicillin-susceptible staphylococci, and Gram-⊖ bacilli including nosocomial strains and with ↑ activity against *Pseudomonas* *Toxicity:* Hypersensitivity reactions, autoimmune hemolytic anemia, disulfiram-like reaction, vitamin K deficiency. Exhibit cross-reactivity with penicillins. Potentiate the nephrotoxicity of aminoglycosides. *MOR:* Structural change in penicillin-binding proteins (transpeptidases). All cephalosporins are typically inactive against *L*isteria monocytogenes, *A*typical pneumonias (Chlamydia, Mycoplamsa), *M*RSA, and *E*nterococci. (*LAME*) Ceftaroline *5th Generation Cephalosporins* *MOA:* Same as that of penicillins. Binds PBP 2z, which is produced by MRSA strains *Clinical use:* Broad Gram-⊕ and Gram-⊖ organism coverage, *including MRSA*; does not cover Pseudomonas *Toxicity:* Hypersensitivity reactions, autoimmune hemolytic anemia, disulfiram-like reaction, vitamin K deficiency. Exhibit cross-reactivity with penicillins. Potentiate the nephrotoxicity of aminoglycosides. *MOR:* Structural change in penicillin-binding proteins (transpeptidases). All cephalosporins are typically inactive against *L*isteria monocytogenes, *A*typical pneumonias (Chlamydia, Mycoplamsa), *M*RSA, and *E*nterococci. (*LAME*) Aztreonam *MOA:* Monobactam. Similar MOA to penicillins: binding to PBPs, causing autolysin production and cellular lysis Binding is nearly all to PBP-3, which is present only in aerobic Gram-⊖ rods *Clinical use:* Aerobic Gram-⊖ bacilli (*Pseudomonas spp.*) Used in penicillin-allergic patients and those with renal insufficiency who cannot tolerate aminoglycosides. Inactive against Gram-⊕ cocci, anaerobic bacteria, and other types of bacteria *Toxicity:* Usually nontoxic; occasional GI upset or rashes due to delayed hypersensitivity, but not immediate hypersensitivity