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BETA-LACTAM Inhibit cell wall synthesis, BETA-LACTAM Inhibit cell wall…
BETA-LACTAM
Inhibit cell wall synthesis
BETA-LACTAM
Inhibit cell wall synthesis
PENICILLINS
Penicillinase-resistant
Methicillin
Highly penicillinase resistant, but NOT acid resistant
Inducer of penicillinase production
Adverse effects:
Haematuria
Albuminuria
Reversible interstitial nephritis
Largely replaced by Cloxacillin
Cloxacillin
Isoxazolyl side chain
Highly penicillinase & Acid resistant
More active than Methicillin against Staphyloccocci, but not MRSA
incompletely but dependably absorbed for oral route
Plasma protein bound >90%
Elimination via kidney, liver
Half-life: 1 hour
having side chain that protect B-lactam ring
Treat infections caused by penicillinase-producing Staphylococci
Except MRSA & NOT resistant to Gram-ve B-lactamase
Dose: 0.25-0.5g QID
severe infections - 0.25-1g iv/im
Antipseudomonal / Extended-spectrum
Carboxypenicillin
Carbenicillin
Not penicillinase resistant
Not acid resistant
Inactive orally
Excrete rapidly in urine
Half-life: 1hr
Used as sodium salt - Sodium for fluid retention in CHF patients
Dose: 1-2g im // 1-5g iv every 4-6 hrs
High doses cause bleeding - interfere platelets function
Indications:
Serious infections: Pseudonomas, Proteus
Burns
Urinary tract infection
Septicaemia
Active against: P. aeruginosa, Indole+ve proteus
Less active: Salmonella, E. coli, Enterobacter
Not active: Klebsiella, Gram+ve cocci
Often combine with Gentamicin
Ticarcillin
More potent than Carbenicillin against Pseudonomas
Ureidopenicillin
Piperacillin
Anti-pseudonomal penicillin
8x more active than Carbenicillin
Active against: Klebsiella
Used in neutropenic/immuno-compromised associated Gram-ve infections & burns
Elimination/Half-life: 1hr
Dose: 100-150mg/kg/day TID im/iv
Max. dose: 16g/day
IV route is preferred when >2g to be administered
Mezlocillin
Active against: Pseudonomas & Klebsiella
Parenteral administration for Enterib bacilli infections
Penicillinase-sensible
Natural / narrow spectrum
PnG
PnV
Acid-resistant
alternative to PnG
Better oral absorption
Peak conc. reach in 1 hour
Half-life: 30-60mins
Activity against:
1) Neisseria
2) Gram-ve bacteria
3) Anaerobes
4) Streptococcal pharyngitis
5) Sinusis
6) Otitis media
7) Minor pneumococcal infections
8) Prophylaxis of Rheumatic fever
Doses: 250-500mg; Children: 125-250mg QID
Aminopenicillin
[Broad/Extended-spectrum]
Bacampicillin
Ester of Ampicillin
A prodrug
Nearly complete absorption in GIT
Largely hydrolysed during absorption
Does not disturb intestinal ecology
Higher plasma levels
Better tissues penetration
Dose: 400-800mg BD
Amoxicillin
Close congener of Ampicillins
not a prodrug
Better oral absorption
Food does not interfere absorption
Higher and more sustained blood levels
Less diarrhea incident
More preferred for:
Typhoid
Bronchitis
Urinary tract infections
SABE
Gonorrhea
Dental infections - 250-500mg TDS 5days
Dose: 0.25-1g TDS oral/im
Ampicillin
Amino substitution in the side chain
some are prodrugs
Not resistant to penicillinase
Not resistant to other B-lactamases
Active against all organisms sensitive to PnG
Active against Gram-ve bacilli:
H. influenza
E. coli
Proteus
Salmonella
Shigella
More active to: Strep. viridans & Enterococci
Moderate active to: Pneumococci, Gonococci, Meningococci
Less active to: Gram+ve cocci
Not affected to:
Penicillinase-producing Staph.
Gram-ve bacilli: Pseudonomas, Kelbsiella, Indole positive Proteus
Anaerobes: Bacteroides fragilis
CHEPHALOSPORIN
3' Generation
Cefpodoxime //
PROXETIL
Oral active ester prodrug of Cefpodoxime
Highly active to:
Enterobacteriaceae
Streptococci
inhibits Staphylococcal aureus
Indications: Respiratory, Urinary, Skin, Soft tissue infections
Ceftriaxone
Longer duration action - Half-life: 8hrs
Once or twice dose per day
Good CSF penetration
Excrete equally in urine and bile
High efficacy & wide ranges:
Bacteria meningitis - especially children
Dose: 4g - 2g iv // child 75-100mg/kg OD 7-10days
Multi-resistant typhoid fever
Dose: 4g iv daily x2days - 2g/day // child 75mg/kg till 2days after fever subsides
Complicated urinary tract infections
Abdominal sepsis & Septicemias
Gonnorhoea, PPNG - single dose 250mg im
Adverse effects:
Hypoprothrombineamia
Bleeding
Cefizoxime
Similar to Cefotaxime
not metabolized
Excreted by kidney at slower rate
Half-life: 1.5-2hrs
Dose: 5-1g 8-12hrly im/iv
Ceftazidime
Indications:
Pseudonomas - highly active
Febrile neutropenic patients with: Hematological malignancy, Burns, etc
Resistant typhoid - 20mg/kg/day
Dose: 0.5-2g im/iv QID, Child 30mg/kg/day
Adverse effects:
Neutropenia
Thrombocytopenia
Rise in plasma transaminases
Rise in blood urea
Cefoperazone
Stronger activity against Pseudonomas
Indications:
Severe urinary infections
Biliary infections
Respiratory infections
Skin soft tissue infections
Meningitis
Septicaemias
Dose: 1-2g im/iv 12hrly
Cefixime
Orally active
Longer acting - Half-life: 3hrs
Indications:
Respiratory infections
Urinary infections
Biliary infections
Dose: 200-400mg BD
Side effects:
Stool changes
Diarrhea
Cefotaxime
Prototype drug
Prominent indications:
Meningitis of Gram-ve bacilli
Life-threatening, resistant, hospital-acquired infections
Septicemias
Infections in immuno-compromised
PPNG urethritis - single dose therapy: Cefotaxime 1g im + Probenecid oral
Dose: 1-2g 6-12hrly im/iv
Children: 20-100mg/kg/day
Cefdinir
Active against B-lactamase producing organisms
Against respiratory pathogens - Gram+ve cocci
Indications:
Pneumonia
Acute exacerbations of chronic bronchitis
ENT - "Otorhinolaryngology"
Skin infections
Dose: 300mg BD
Cefibuten
Against: Gram+ve & Gram-ve bacteria
Stable to B-lactamase
Indications: UTI, RTI, GIT infections
Dose: 200mg BD or 400mg OD
Highly resistant to Gram-ve B-lactamase
Less active: Anaerobes & Gram+ve cocci
4' Generation
Cefepime
Highly resistant to B-lactamases
Active against:
P. aeruginosa
Staph. aureus
High potency
Extended Spectrum
Effective for // Indicarions:
Hospital-acquired pneumonia
Febrile neutropenia
Bacteraemia
Septicaemia
Dose: 1-2g iv 8-12hrly
Cefpirone
Treat serious and resistant hospital-acquired infections: Septicaemias & Lower RTIs
Zwitter ion character - better penetration thru porin channels of Gram-ve bac.
Resistant to B-lactamase
Inhibits type I B-lactamsase producing Enterobacteriaceae
More potent against Gram+ve
Dose: 1-2g im/iv 12hourly
2' Generation
Cefoxitin
Uses:
1) Serratia
2) Indole positve proteus
3) B. fragilis
4) Gram-ve bac - highly resistant to B-lactamases
5) Anaerobes
6) Mixed obsteric/surgical infections
7) Lung abscess
Dose: 1-2g im/iv every 6-8hr
Cefuroxime axetil
Ester form
Effective orally, but incomplete absorption
Activity depends on hydrolyses & release of Cefuroxime
Dose: 250-500mg BD
Children - half dose
Cefuroxime
resistant to Gram-ve B-lactamase
High activity:
PPNG - single dose therapy
Ampicillin-resistant H. influenza
Meningitis caused by: H. influenza, Meningococci, Pneumococci
Cefaclor
Oral route
more active compared to 1st generation
Against:
H. influenza
E. coli
Proteus mirabillis
Anaerobes in oral cavity
More active to Gram-ve
Some are active to Anaerobes
1' Generation
Cephalexin
Similar to Cefazolin
Orally effective
Less active against H. influenza
Dose: 0.25-1g 6-8hrly
Children - 25-100mg/kg/day
Cephradine
Orally active, but causes diarrhea
Available for paranteral
Dose: 0.25-1g 6-16hrly oral/im/iv
Cefazolin
Active against most PnG sensitive:
Streptococci
Gonococci
Meningococci
More active: Klebsiella & E. coli
Used for surgical prophylaxis
Dose:
Mild - 0.25g 8hourly im/iv
Severe - 1g 6hourly im/iv
Cefadroxil
Close congener of Cephalexin
Dose: 0.5-1g BD
1960s
Active to Gam+ve
Weak to Gram-ve
semi-synthetic antibiotics
derived from Cephalosporin-C
obtained from fungus Cephalosporium
Bactericidal
same MOA as Penicillin
Adverse effects
Generally well-tolerated but more toxic than Penicillin
Pain after IM injection
Thrombophlebitis on IV injection
Diarrhea - alteration of gut ecology or irritation effects
Hypersensitivity reactions
10% ppl who allergy to Penicillin show cross reactivity with Cephalosporin
Nephrotoxicity
Bleeding - Hypoprothrombinaemia
Neutropenic & Thrombocytopenia - Ceftazidine
Disulfram-like interaction with alcohol - Cefoperazone
Uses
Alternative to PnG
Respiratory, Urinary, Soft tissue infections
Penicillinase-producing Staphylococcal infections
Septicaemias - in combination with Aminoglycosides
Surgical prophylaxis
Meningitis:
H. influenza
Enterobacteriaceae
Pseudonomas meningitis - Best treat by Ceftazidime + Gentamicin
Gonorrhoea - PPNG
Chancroid
Typhoid - Ceftriaxone & Cefoperazone are fatest acting
Mixed aerobic-anaerobic infections
Hospital-acquired infections resistant to common antibiotics
Dental infections
CARBAPENAMS
Imipenem
Extreme potent
Very broad spectrum:
Gram+ve cocci
Listeria
Enterobacteriacaea
P. aeruginosa
Anaerobes - Bact. fragilis & Cl. difficile
Resistant to B-lactamase & Penicillinase-producing Staph.
Rapidly hydrolysed by dehydropeptidase I, located on the brush border of renal tubular cells
In combination with Cilastatin - protect from dehydropeptidase I
Imipenem/Cilastatin:
0.5g iv 6hrly (max 4g/day)
effective for wide range serious hospital-acquired infections: Neutropenic, Cancer, AIDS
Propensity to induce seizure at high dose & predisposed pt.
Meropenem
Not required Cilastatin - Not sensitive to renal dipeptidase
Less active against Gram+ve
More active against Gram-ve
Less likely to cause seizure
Doripenem
Similar spectrum to Meropenem
Greater activity against some resistant isolates Pseudomonas
Ertapenem
Longer halt-life - OD dosing
Active against Enterobacteriaceae & Anaerobes
useful in intra-abdominal and pelvic infections
MONOBACTAMS
Aztreonam
A novel B-lactam - one ring missing
At low conc. - Inhibits Gram-ve bacilli & H. influenza
At moderate conc. - Inhibit Pseudomonas
NOT inhibit Gram+ve cocci & Feacal anaerobes
Resistant to B-lactamases
Indications:
Hospital-acquired infections: Urinary, Biliary, GI, Female genital tracts
used in allergic to Penicillin - lack of cross sensitivity
Eliminated in urine
Half-life: 1.8hrs
Dose: 0.5-2g im/iv 6-12hrly