Drugs Flashcards
(62 cards)
Streptomycin
- rapidly bactericidal against aerobic Gram-negative bacteria
- used for one and one thing only, tuberculosis (used in combination with other drug, rifampin and INH)
Tobramycin
Gentamicin
mainly used in cases of severe infection by aerobic Gram-negative infections that are likely resistant to other drugs
-usually used in combination with Beta-lactam antibiotics for synergistic effects and prevent emergence of resistance.
Gentamicin is the preferred simply due to cost.
Gentamicin, Tobramycin are some of the most nephrotoxic aminoglycosides. Nephrotoxic effects are reversible upon discontinuation
Amikacin
the preferred drug if gentamicin and tobramycin don’t work.
It is a cyborg of kanamycin (part synthetic) but is less toxic.
again, gram negative aerobic bacteria
Neomycin
Kanamycin
both drugs are too toxic for ingestion and are primarily topical use.
They are used on infected surfaces- skin or eyes, or injected into joints, pleural cavities, tissue spaces and abscess cavities.
ointments are often formulated as a neomycin-polymyxin-bacitracin combination - neosporin
Neomycin is one of the most nephrotoxic
Aminoglycoside toxicity
All aminoglycosides are nephrotoxic, most likely if taken more than 5 days.
Neomycin, gentamicin, tobramycin
are some of the most toxic
All aminoglycosides are ototoxic: auditory damage (tinnitus, high frequency hearing loss, or vestibular damage, vertigo, ataxia
Again, ototoxic effects most likely to appear if taken more than 5 days or at higher doses in elderly.
Neomycin, kanamycin and amikacin cause the most auditory damage while streptomycin, gentamicin cause the most vestibular damage.
What are the mode of action of Aminoglycosides, Tetracyclines
Aminoglycosides; they can be bacteriocidal and act be performing 3 things. They inhibit protein initiation, protein elongation and inhibit proofreading leading to the post antibiotic effect.
Tetracyclines only do one of those things, they bind to the 30S subunit and prevent elongation so they are bacteriostatic. They are however much broader and can cover aerobic, anaerobic GN GP bacteria some protozoa.
Tetracyclines have basically all the same activity, what differs between them?
The half life, the longer the half life, the more compliance:
Short (6-8) :
Oxytetracycline
Tetracycline
(oral)
intermediate (12):
Demeclocycline
(oral)
Long (16-18):
*doxycycline (oral or IV)
minocycline (oral)
Superfucking long
*Tigecycline (IV) only 36 hours
Tetracycline uses
Rickettsial infections:
________________________
Rocky mountain spotted fever, typhus, Q fever
Sexually Transmitted Infections:
______________________________
Chlamydia, urethritis, epididymitis, cervicitis
Respiratory Tract infections:
_______________________________
community-acquired pneumonia
Skin and Soft-tissue infections:
________________________________
community-acquired staph, severe acne
**Anthrax, malaria, Lymes disease: doxycycline
***community acquired pneumonia, MDR bacteria, MDR S. aureus (MRSA), MDR enterococci (VRE) , MDR acinetobacter, Penicillin-resistant streptococci
Tetracycline toxicities
Absorption of orally administered drugs is impaired by food (except for doxycycline
and minocycline) and alkaline pH. • Tetracyclines chelate multivalent cations (Ca2+, Mg2+, Fe2+, and Al3+). • Absorption is therefore also impaired by these cations and by products that contain
them (e.g., dairy products and antacids).
(GI disturbances): fine
(Bony structures and teeth): tetracyclines will bind to the calcium on newly deposited teeth and is of primary concern for young children.
(Photosensitization): systemic administration can produce mild-to severe sensitivity reactions in skin of treated individuals
Liver disturbances:
-contraindicated during pregnancy because of hepatoxic effects
What are the pharmacokinetics of macrolides (50S inhibitors)
Aminoglycosides: aerobic gram negative
Macrolides: mostly aerobic gram positive
Include erythromycin, clairthromycin, telithromycin, azithromycin
they inhibit the translocation step of elongation.
Antibacterial properties of all are again similar like tetracycline, they have difference in half lifes.
(**only thing is that telithromycin is active against many macrolide resistant bacteria)
Erithromycin - short, 1.5 hours
Clarithromycin: 6 hours
Telithromcyin 10 hours
Azithromycin (Z pack) -3 days
What are the uses of macrolides?
- Pertusis
- Chlamydial infections
- **Streptococcal pharyngitis the best!
- for those allergic to penicillin, useful alternative for Staph infections of skin or soft tissue
So mostly respiratory tract infections (community acquired pneumonia (telithromycin), chronic bronchitis
What is toxicity of macrolides?
GI effects: anorexia, nausea, vomiting and diarrhea
(just eat food)
Liver toxicity: can produce acute cholestatic hepatitis, likely a hypersensitive reaction
Telithromycin can only be used for community acquired pneumonia because of toxicity.
Clindamycin
A lincosamide - it is only for gram positive bacteria and bacteriostatic. Used for treatment of skin and soft tissue infections. It was once ideal for staph but now MRSA will not be effected.
Quinupristin/Dalfopristin
These are streptogramins that are taken in combination through IV.
Used for treatment of infections caused by vancomycin resistent enterococcus faecium. Also used for complicated skin infections caused by methicillin sensitive S:aureus
Linezolid: super important
One of the newest drug, wonderdrug for Multi Drug resistant bacteria including MRSA VRE and penicillin resistant streptococci.
What are the two functional classes of DNA synthesis inhibitors and their members/
Antifolate drugs: which inhibit bacterial biosynthesis of DNA (can’t make purines)
- Sulfonamides (PABA analogs)
- Trimethoprim
- Both
DNA gyrase/topo 4 inhibitors: block bacterial DNA synthesis by blocking bacterial topoisomerase II (DNA gyrase) and Topoisomerase 4
- fluoroquinolones.
What is the mechanism of action of
Sulfonamides, trimethoprim
Sulfonamides are PABA analogs which act as competitive inhibitors of dihydropteroate synthase which converts PABA to dihydrofolic acid.
bacterial DHFR is inhibited by Trimethoprim which converts Dihydrofolic acid to THF.
Combination is often bacteriocidal, alone they are bacteriostatic
Sulfisoxazole
Sulfamethoxazole
Rarely used, these are sulfonamides used only for treating UTIs
Sulfasalazine (**)
Worth knowing because it is widely used in ulcerative colitis, enteritis and other IBDs. It is the front line for it.
Adverse effects of TMP-SMX
Sulfonamides:
They are all partially cross-allergenic so they promote allergies. (short course of treatment< 5 days)
- fever, skin, rashes, dermatitis, photosensitivity, urticaria, nausea, vomiting, diarrhea
- may precipitate in urine** causing crystalluria (super painful), hematuria or even obstruction
Longer course of treatment > 5 days
-megaloblastic anemia and leukopenia
What are uses of TMP-SMX (Bactrim)
- UTIs
- Pneumocystis jiroveci pneumonia - number one opportunistic killer of AIDS
- Acute exacerbations of chronic bronchitis
**-systemic salmonella infections
- prostatitis
- shigellosis
Fluoroquinolones: pharmacodynamics and uses and toxicities
Ciprofloxacin Lomefloxacin Levofloxacin Ofloxacin -(gram negative activity-gyrase)
Gemifloxacin, moxifloxacin
(gram positive-topo IV)
-bacterial diarrhea caused by Shigella, E. coli and Campylobacter
**Ciprofloxacin is the drug of choice for anthrax
Levofloxacin, gemifloxacin, moxifloxacin (aka the “respiratory FQs”) used increasingly for treatment of upper and lower respiratory tract infections
Sulfasalazine:
Used for IBD (ulcerative colitis, enteritis .
Sulfisoxazole and sulfamethoxazole
are used almost exclusively for UTIs