Lec2 Flashcards
Drugs that inhibit bacterial protein synthesis
1.Macrolides
2.clindamycin
3.tetracyclin
4.aminoglycosides
Macrolides examples
1.Erythromycin 2.clarithromycin 3.Azithromycin
Macrolides mechanism of action
Bacteriostatic
Inhibit 50s ribosome subunit -> lead to misreading of mRNA->Inhibit bacterial protein synthesis
Macrolides root of administration
Oral
Erythromycin distributes well to all body fluid except…….
CSF
Root of excretion for erythromycin and azithromycin
In the Bile as active drugs
Erythromycin may used as a replacement for penicillin why?
It’s used for patient who have penicillin allergy Cuz It’s effective against many of the same organisms as penicillin
When does the erythromycin is used?
In gastroparesis cuz it promotes gastric emptying
Drug has the same effect as erythromycin and also effective against haemophilus influenza
Clarithromycin
Proffered therapy for urethritis caused by chlamydia trachomatis
Azithromycin
Adverse drug reactions of macrolides
-GIT upset nausea, vomiting, abdominal pain & diarrhoea
-ototoxicity: associated with erythromycin, especially at high dose
Contraindications of macrolides
It can accumulate in the liver in the patient who have hepatic failure
Drug to drug interaction of macrolides
Clindamycin mechanism of action
Same as macrolides
Root of administration of clindamycin
IV & oral-limited by gastrointestinal tolerance-
Distribution of clindamycin drugs in the body
Well in all body fluid and boon, poor entry into the CSF
Clindamycin root of excretion
Bile
Accommodated clindamycin occur in
Severe renal impairment or hepatic failure
Clindamycin used against….
Gram positive organisms, including MRSA and streptococcus, and anaerobic bacteria
Adverse drug reactions to clindamycin
1.Skin rashes
2 Diarrhea, which may represent a serious pseudomembranous colitis caused by overgrowth of C. difficile.
C. Difficile treatment
Oral vancomycin
Tetracyclines examples
Doxycycline or tetracycline
Mechanism of action
It has the same effect as macrolides but it bind to the 30s subunit of bacterial ribosome not the 50s subunit
Root of administration of tetracycline
Oral
Distribution of tetracycline antibiotics
Penetration into most body fluids is adequate , cross the
placental barrier and concentrate in fetal bones and teeth
Root of elimination of tetracyclines antibiotics
Primarily in urine but doxycycline eliminated via the bile
Which drug is preferred in tetracycline for renally compromised patients
Doxycycline (excretion via bile into the feces)
Adverse drug effects of tetracyclines
Gastric discomfort -commonly via irritation of the gastric mucosa.
Phototoxicity -if exposed to ultraviolet rayes
Vestibular dysfunction -dizziness,vertigo and tinnitus
Contraindications of tetracycline antibiotics
Don’t se if
-pregnant
-breast-feeding Women
-less than 8 years of age
Aminoglycoside examples
Streptomycin, amikacin or gentamicin
Mechanism of action for Aminoglycosides
Same as tetracycline
Root of administration of Aminoglycosides
IV or IM
Distribution of Aminoglycosides in the body
Poor penetration to CSF also it has a good entry to inflamed tissues
Root of excretion
Via glomerular filtration
Adverse drug effect for Aminoglycosides
Nephrotoxicity
ototoxicity (due to auditory or vestibular nerve damage)
Drug to drug interactions for Aminoglycosides
Ototoxicity is enhanced by loop diuretics(e.g.furosemide)
Drugs that inhibit bacterial nucleic acid synthesis
- Quinolones
- Rifampcin
Quinolones examples
Levofloxacin
ciprofloxacin
Mechanism of action of quinolones
Bactericidal
Inhibit DNA gyrase (bacterial topoisomerarse||)-> relaxation of supercoiled DNA(promoting DNA strand breakage) -> inhibit bacterial nucleic acid synthesis
DNA gyrase
DNA gyrase : preserve the state of supercoiling in replicating and non-replicating bacterial chromosomes )
Distribution of quinolones drug in the body
Distribute well in all body fluids and tissues
Root of excretion for quinolones
Renally (dosage adjustment is needed in cases of renal failure)
Adverse drug effect for quinolones
-Phototoxicity (if exposed to uv)
-Tendinitis or tendon rupture
Drug to drug interactions for quinolones
Inhibit hepatic drug metabolism & prolong action of theophylline and warfarin
Rifampcin mechanism of action
Bactericidal
Inhibit the DNA-dependant RNA polymerase of mycobacterium TB-> prevent transcription of DAN into mRNA
Why rifampicin has no effect in some of the mycobacteriumTB
The mycobacterium TB become resistant to the drug because of a mutation in it’s DNA-dependant RNA polymerase gene
Root of administration for Rifampicin
Oral
Distribution of
Distribution of the rifampicin in the body
Widely distributed to all body fluids and organs(including the CSF)
Potent liver enzymes inducer
Rifampicin
Root of elimination
Primarily through the bile and into the feces
a small percentage is cleared in the urine
Adverse drug effect of rifampicin
-Red-orange secretions ( tears – urine -….) -Thrombocytopenia
-Hepatotoxicity (Hepatitis)
Drug to drug interactions of rifampicin
Hepatic enzyme inducer: increase metabolism of warfarin,
phenytoin, oral contraceptive pills
Antibiotics antagonism
indicates that decreased anti-microbial effect of a drug when combined with another, leading to decreased response
Mechanisms of antagonism include:
-Decreased bactericidal activity by bacteristatic agent e.g. tetracycline and Penicillins
-Increased enzymatic inactivation e.g. ampicillin decrease pipracillin activity
Rule of right (5 Rs)
1.right drug
2. Right dose
3. Right route
4. Right time (interval and duration)
5. Right patient
