antimicrobial drugs

Class: Sulfonamide
Mech.: Comp. inhib. of PABA incorp. into dihydropteric acid → inhib. of folic acid.
Bacteriostatic.
Absorption: Rapidly absorbed in GI tract. Parenteral.
Distribution: Widely distrib; CSF. Crosses placenta.
Metab.: Acetylated in liver
Excretion, t_: Renal filtration, secretion
Toxicity/S.E.s: Hypersensitivity—fever, rash, photosensitivity; UT disturbances—
deposition of crystalline aggregates; hematopoetic
disorders—dyscrasias
Utility: Uncomplicated UTIs, trachoma (contag. disease of eyelid, conjunct,
cornea), nocardiosis (tuberculosis-like infect.), prophylaxis (burnt skin,
suppressing recurring UTIs, rheumatic fever)
Special Features: Spectrum—gram +, gram -. Less renal toxicity than other
sulfas. Protoype.

Class: Sulfonamide
Mech.: Comp. inhib. of PABA incorp. into dihydropteric acid → inhib. of folic
acid. Bacteriostatic.
Absorption: Rapidly absorbed in GI tract (slower than isoxazole). Parenteral.
Distribution: Widely distrib; limited CSF. Crosses placenta.
Metab.: Acetylated in liver
Excretion, t_: Renal filtration, secretion
Toxicity/S.E.s: Hypersensitivity—fever, rash, photosensitivity; UT
disturbances— deposition of crystalline aggregates;
hematopoetic disorders—dyscrasias
Utility: Uncomplicated UTIs, trachoma (contag. disease of eyelid, conjunct,
cornea), nocardiosis (tuberculosis-like infect.), prophylaxis (burnt skin,
suppressing recurring UTIs, rheumatic fever)
Special Features: Spectrum—gram +, gram -.

lass: Sulfonamide
Mech.: Comp. inhib. of PABA incorp. into dihydropteric acid → inhib. of folic acid.
Bacteriostatic.
Absorption: Rapidly absorbed in GI tract. Parenteral.
Distribution: Widely distrib; good CSF. Crosses placenta.
Metab.: Acetylated in liver
Excretion, t_: Renal filtration, secretion
Toxicity/S.E.s: Hypersensitivity—fever, rash, photosensitivity; UT disturbances—
deposition of crystalline aggregates; hematopoetic
disorders—dyscrasias
Utility: Uncomplicated UTIs, trachoma (contag. disease of eyelid, conjunct,
cornea), nocardiosis (tuberculosis-like infect.), prophylaxis (burnt skin,
suppressing recurring UTIs, rheumatic fever)
Special Features: Spectrum—gram +, gram -.

Class: Sulfonamide
Mech.: Comp. inhib. of PABA incorp. into dihydropteric acid → inhib. of folic
acid.
Absorption: Poorly absorbed in GI tract.
Distribution: GI tract
Metab.: Hydrolized to active form by intest. bacteria.
Excretion, t_: feces
Toxicity/S.E.s: Interferes w/normal flora → ↓ vit. K synth.
Utility: Active in bowel lumen. Used prior to surgery to reduce microbe
population. Treat inflammatory bowel disease, rheumatoid arthritis
Special Features: Broken down in intestines to liberate 5-aminosalicylate (antiinflammatory).

Class: Sulfonamide
Mech.: Releases silver → toxicity for bacteria and fungi.
Absorption:
Distribution: Topical
Metab.:
Excretion, t_:
Toxicity/S.E.s:
Utility: Used topically to reduce infection of burns, but not to treat established
infections.

Class: Sulfonamide
Mech.: Comp. inhib. of PABA incorp. into dihydropteric acid → inhib. of folic
acid.
Absorption:
Distribution: Ophthalmic application. Penetrates into ocular fluids at high conc.
Metab.:
Excretion, t_:
Toxicity/S.E.s:
Utility: Ophthalmic infections
Special Features: High aqueous concentrations are not irritating.

Class:
Mech.: Acts on two sequential steps in synth of folic acid. PABA competitive
inhib, dihydrofolate reductase inhib. Bacteriostatic.
Absorption: Oral, IV
Distribution:
Metab.:
Excretion, t_:
Toxicity/S.E.s: Megaloblastic anemia, leukopenia, granulocytopenia (prevented
by admin. of folic acid)
Utility: Uncomp. UTIs, otitis media, acute exacerbations of chronic bronchitis,
various pneumonias. DOC for Travelers’ diarrhea, P. carinii pneumonia,
Shigella enteritis, systemic Salmonella infects, prostatitis.
Special Features: Trimethoprim = highly selective inhib. of bacterial dihydrofolate
reductase.

Class:
Mech.: Bacteriostatic. Inhib protein synth by binding to 50S subunit.
Absorption: Rapid oral absorption
Distribution: Body fluids, good CSF. Crosses placenta. Milk.
Metab.: Liver (glucuronyl transferase)
Excretion, t_: Urine (filtration, secretion), 1.5-3.5 hr.
Toxicity/S.E.s: Bone marrow depression (anemia, leukopenia, thrombocytopenia,
prob. due to inhib. of mitoch. protein), aplastic anemia
(allergic/idiosync, rare, irreversible, often fatal), Gray Baby
Syndrome (neonate overdose due to reduced ability to conjuate
CA and secrete metabolites), superinfection (S. aureus,
Pseudomonas, fungi, can be life threatening).
Utility: DOC for severe Bacteroides infects (esp. CNS), backup for memingitis,
rickettsial infects, brucellosis.
Special Features: Never use if safer antibiotic avail. Never use for mild infects.

Class: Tetracycline
Mech.: Active uptake into bacteria →inhib protein synth by binding to 30S
ribosome. Bacteriostatic
Absorption: Oral adequate, but incomplete. Impaired by divalent cations. IM
painful. IV may cause thrombophlebitis. Never intrathecal.
Distribution: Good CSF. Conc. in liver → enterohepatic circ. Penetrates most
tissues and fluids. Crosses placenta.
Metab.:
Excretion, t_: filtration (1°), bile
Toxicity/S.E.s: GI — burning, discomfort, nausea, vomitiing; superinfection — due to broad
spectrum, candida albicans (1°), staph enterocolitis, pseudomemb. colitis;
hepatotoxicity (esp. in pregnancy); renal toxicity; Fanconi synd.; perm. brown
discoloration of teeth; slowing of bone growth; phototoxicity; thrombophlebitis;
hematopoetic changes; rare hypersens. rxns.
Utility: gram - cocci, gram - bacilli, acid fast bacilli, chlamydiae, mycoplasma,
rickettsia, spirochetes. No effect on viruses or fungi. Also used for
acne, prophylaxis for Travelers’ diarrhea.
Special Features: Broad spectrum. Decreased effect of oral contraceptives.

Class: Tetracycline
Mech.: Active uptake into bacteria →inhib protein synth by binding to 30S
ribosome. Bacteriostatic
Absorption: Good oral absorption. Impaired by divalent cations. IM painful. IV
may cause thrombophlebitis. Never intrathecal.
Distribution: Good CSF. Conc. in liver → enterohepatic circ. Penetrates most
tissues and fluids. Crosses placenta.
Metab.:
Excretion, t_: bile; doesn’t require renal excretion
Toxicity/S.E.s: GI — burning, discomfort, nausea, vomitiing; superinfection — due to broad
spectrum, candida albicans (1°), staph enterocolitis, pseudomemb. colitis;
hepatotoxicity (esp. in pregnancy); renal toxicity; Fanconi synd.; perm. brown
discoloration of teeth; slowing of bone growth; phototoxicity (more than others);
thrombophlebitis; hematopoetic changes; rare hypersens. rxns.
Utility: gram - cocci, gram - bacilli, acid fast bacilli, chlamydiae, mycoplasma,
rickettsia, spirochetes. No effect on viruses or fungi. Also used for
acne, prophylaxis for Travelers’ diarrhea.
Special Features: Broad spectrum. Decreased effect of oral