CD 07 Flashcards
How are antibiotic drugs classified?
- By their effect on bacteria
- By their spectrum of activity
- Mechanism of action
What does Bacteriostatic mean?
Inhibit bacterial growth and replication
Bactericidal mean ?
Kill bacteria
What is Narrow spectrum: ?
Limited to specific microbe families
What is Broad spectrum?
Extensive, affects Gram +/Gram -
According to the mechanism of action Antibiotics are classified in 3 broad classes. However in class 1 reaction what energy source Bacteria use
Host and organism similar
Bacteria can use alternative energy sources
in Class II drugs antibiotics works on
Synthesis of essential growth factors
E.g. folate synthesis
In Class III drugs antibiotics works on
Assembly of macromolecules
DNA, RNA, proteins
Peptidoglycans
What are the unwanted effects of antibiotics?
- Gastrointestinal toxicity
2. Nephrotoxicity
What are the unwanted effects of antibiotics?
Idiosyncratic reactions
Skin rashes, eruptions, itching
Liver toxicity
Blood cells (hematological toxicity e.g. anemia)
In bacteria How Folate synthesis work?
PABA converted to (Para-aminobenzoic acid (PABA) is a chemical found in the folic acid) =>DHF=>THF=>Purine and Methionine and Thymidylate
Does (Sulfonamides) Sulfadiazine is static or cidal?
• BacterioSTATIC(Gram+/-)
Pharmacokinetics of sulfadiazine
Mostly absorbed orally
Metabolised in liver
Excreted by kidney (t1/2 =12h)
What are the Unwanted effect of sulfadiazine?
Stevens-Johnson Syndrome
Hypersensitivity reactions
Hepatitis
Bone marrow suppression
Clinical Use of sulfadiazine
Inflammatory bowel disease (sulphasalazine)
For infected burns
topical: silver sulfadiazine
Trimethoprim is a bacterio static or bacterio cidal ?
Bacterio static for both G+ or G- bacteria
Trimethoprim inhibit ?
Inhibits dihydrofolate reductase
Synergistically prevent folate synthesis
PK of Trimethoprim
Given orally
Fully absorbed from GI tract
High conc. in lung, kidney,
Eliminated by the kidney (t1/2 =24)
Unwanted effects of TMP ?
Folate deficiency=> megaloblastic anaemia (long term use) Nausea, vomiting Blood disorders Rashes
Clinical Use of TMP?
Urinary tract infections(UTI)
Bacterial DNA replication Occurs by what?
Binary fission
Bacterial DNA replication occurs by
bianary fission
Work of Topoisomerase of DNA in Bacteria replication is?
- Break rotate and reseal
- It removes extra DNA supercoils
- Separates intertwined DNA
How many Types of Topoisomerase is?
2 Types
- DNA gyrase (Topoisomerase ll )
- Topoisomerase IV
What are the Quinolones (Fluoroquinolones) class of drug?
Ciprofloxacin
Moxifloxacin
anything with oxacin are quinolones groups
What Quinolones inhibits?
DNA gyrase in (G-) bacteria Inhibits topoisomerase (IV) in Gram positive bacteria
Quinolones are static or cidal and narrow spectrum or broad spectrum?
are Bacteriacidal (Kill) and Broad spectrum
Pharmacokinetics of Quinolones /Fluoroquinolones are
Absorb orally
Accumulate perdominantly in kidney Prostate and lung
Excrete by urine
Quinolones or Fluoroquinolones can not cross BBB ?
Except ofloxacin
Quinolones or fluoroquinolones are Metabolised by which enzyme
CYP 450
As quinolones are predominantly exceriated by kidney so what needs to monitor and have to do?
so Dose adjustment is required for renal failure patients
Unwanted effect of Quinolones or fluoroquinoles are
skin rash and GI problem
Headache and dizziness
Quinolones/ fluoroquinoles Clinical Use
Travellers diarrhoea (moderate/severe) Gonorrhoea Prostatitis, bone and joint infections (if no alternative)
Important drug drug interection of quinolones is
Al and Mg containing ANTACIDS inhibit abosorbpoton from the gut.
Ciprofloxacin is a moderate inhibitor of CYP1A2 as a result
- Caffeine (limited clinical importance)
* Theophylline (historically most important)
Clozapine, & olanzapine (antipsychotics) metabolized by which enzyme?
by CYP 1A2
Who are the tetracycline group of drugs ?
Doxycycline, minocycline, tetracycline
Tetracyclines are bacteriostatic or cidal?
static
Tetracycline inhibit
30s by binding of aa-tRNA
What are the unwanted effect of tetracycline
tetracycline deposition in bone and teeth
Sunburn so avoid sun light
hepatotoxicity
avoid in pregnency
Clinical use of tetracycline is
Acne
Respiratory infections
Aminoglycosides class of drugs are
gentamycin, tobramycin
How aminoglycosides are work against bacteria?
Inhibit 30s miscoding mRNA
Aminoglycocydes are bactrio?
Cidal
What is the pharmcokinetics of Aminoglycosides?
IV or IM given
eleminate via kidney
What are the unwanted effect of Aminoglycosides
Allergy
Nephrotoxicity
Renal impairment
What are the clinical use of aminoglycosides for?
Pneumonia
Meningitis
What are the Macrolides group of drugs?
Erythromycin
Clarithromycin
Azithromycin
Roxithromycin
How macrolides work against bacteria?
Inhibit 50s ribosomal subunit
Dissociation of tRNA
Does macrolides are static or cidal
Static
What is the pharmacokinetics of Macrolides?
Orally given metabolised in liver and excreted by kidney.
they are CYP 1A2 and 3A4 inhibitor
Drug drug interaction of Macrolides are also CYP 1A2 and 3A4 inhibitor
Benzodiazepines
Simvastatin
Warferin
What are the unwanted effect of Macrolides?
GI toxicity
Cardiac toxicity
What are the clinical usage of Macrolides
Respiratory infection
Skin infection
