Pharmacology Antimicrobials Flashcards
Treatment regime for common cold (acute rhinitis)
Symptomatic:
-NSAIDs and/or paracetamol -Nasal Decongestant ( a1- adrenergic agonist)
Nasal decongestants used for acute rhinits
Phenylephrine (short-acting)
Oxymetazoline (longer-acting)
Cautions with Intranasal α1-adrenergic agonists?
rebound nasal congestion (rhinitis medicamentosa).
When used for more than 3 days
Treatment of Allergic Rhinitis
Antihistamine (H1 receptor antagonists)
1st gen
Diphenhydramine
Chlorpheneramine
short/intermediate acting cross BBB — sedation and psychomotor impairment atropine -like effect 2nd gen Cetrizine Loratidine longer acting low incidence of sedation
Topical intranasal antihistamine for Allergic Rhinitis
Azelastine
Intranasal corticosteroids for Allergic Rhinitis
Beclomethasone
Bbbudesonide
Empiric antimicrobial therapy for Acute bacterial sinusitis
Amoxycillin + Clavulanic acid
Moa of Amoxycillin
Inhibits bacterial transpeptidases ⇒ inhibit crosslinking & cell wall synthesis⇒ lysis & cell death
Examples of β-Lactamase Inhibitors
Clavulanic acid (with amoxycillin & ticarcillin)
Sulbactam (combined with ampicillin)
Tazobactam (combined with piperacillin)
Cephalosporins drugs
1st generation: Cephalexin
2nd generation: Cefaclor
3rd generation: Ceftazidime
Pharyngitis/Tonsillitis: Antibiotics regimen
S. pyogenes - highly susceptible to penicillins
• Amoxycillin 8hrly for 10 days
Patients with a history of acute rheumatic fever • Benzathine penicillin (IM – single dose)
For penicillin-sensitive (allergic) patients : ▪ Macrolide or Clindamycin
Macrolides drugs
❑ Erythromycin
❑Clarithromycin
❑ Azithromycin
Moa of Macrolides
Bind 50S subunits of bacterial ribosomes & inhibit protein synthesis
Uses of macrolides
-Penicillin-sensitive (allergic) patients
– Infections caused by mycoplasma, legionella & chlamydial
– Clarithromycin: Infections (M avium complex, H. pylori)
Tetracyclines drugs
❑ Doxycycline
❑ Tigecycline
MoA of Tetracyclines
Bind 30 S subunits of bacterial ribosomes & inhibit protein synthesis
PK of Tetracyclines
Absorption↓↓ by food, cations (Ca2+, Mg2+, Fe2+ or Al3+) and byiron preparations like ferrous sulfate
Milk, dairy products, & antacids also ↓↓absorption
Chelate with calcium & get deposited in teeth & growing bones
Cross the placenta & also secreted in milk
Doxycycline & Tigecycline undergo biliary excretion
No dosage adjustment in renal failure
Uses of Tetracyclines
Infections caused by gram-positive/negative bacteria, rickettsiae,
chlamydiae, legionella, and mycoplasms
• Tigecycline: Multidrug resistant organisms such as MRSA, VREF, PRE
ADRs of Tetracyclines
• GI disturbances – direct irritation & effects on gut flora (Clostridium difficile associated diarrhea)
• Photosensitivity
• Teratogenic:
– Permanent yellow or brown discoloration of teeth in the fetus – Impairment of fetal long bone growth
Tetracyclines Contraindications:
▪ Pregnancy
Risk of hepatotoxicity in the mother
Teratogenicity
▪ Young children (< 8 years)
Discoloration of teeth & inhibition of bone growth in children
Otitis externa treatment regimen
Antiseptic-olive oil: to cleanse the ears / drying agent
Antibacterial ear drops
Neomycin; Chloramphenicol
Topical antifungals: Clioquinol or Nystatin
Combined antimicrobial + corticosteroid ear drops
Dexamethasone + Framycetin & Gramicidin (antibact. anifungal)
Alternatives for Amoxicillin+clavulanic acid for Otitis media
Cefuroxime, Cefaclor, Macrolides
Bronchitis treatment regimen
Treatment: largely symptomatic
• Consider antimicrobials if:
• Pertussis (whooping cough)
Use a macrolide
Anti-influenza drugs
Adamantane derivatives:
Amantadine
Neuraminidase inhibitors:
Oseltamivir: Prodrug given orally
Zanamivir (inhalation)
Amantadine MOA:
Block the M2 proton ion channel of the virus particle and inhibit uncoating of the viral RNA (influenza A) thus preventing their replication
Neuraminidase inhibitors MOA:
Inhibit neuraminidase, thereby prevent the release of new virions and their spread from cell to cell
ADRs of NA inhibitors
GI discomfort and nausea (oseltamivir)
Cough and bronchospasm (zanamivir)
Caution: Asthma & COPD (zanamivir)
Pneumonia: Treatment
CAP:
Uncomplicated:
• Benzylpenicillin or amoxicillin
• Macrolides (azithromycin) if patient allergic to penicillins
Severe:
▪ Cefuroxime or cefotaxime + azithromycin
▪ Vancomycin, Linezolid or Ceftaroline (if MRSA suspected)
❑ Atypical pneumonia:
Macrolide or tetracycline (doxycycline)
HAP Pneumonia: Treatment
Pseudomonas: Ceftazidime + Fluoroquinolone, Imipenem
MRSA: Vancomycin, Linezolid, Ceftaroline
Aspiration pneumonia:
Beta-lactam/beta-lactamase inhibitor or clindamycin or metronidazol plus amoxicillin.
COVID-19: Specific Therapy
Low-dose dexamethasone
Remdesivir:
Nucleotide analogue that inhibits viral RNA polymerases Must be given within 7 days of when symptoms start
Used for severe COVID-19
ANTI TUSSIVES Drugs
(opioids): Centrally acting
Codeine
Pholcodeine
Dextrometharphan:
• Centrally acting NMDA receptor antagonist.
Benzonatate
- Local anesthetic
-Acts by anesthetizing the stretch receptors in the respiratory passages, lungs, & pleura ↓ cough reflex
MUCOLYTICS drugs
ACETYLCYSTEINE:
• viscosity of mucus and sputum by cleaving disulfide
bonds of mucoproteins
Uses: Cystic fibrosis & chronic bronchitis
BROMOHEXINE:
• Depolymerises mucopolysaccharides of mucus &
lysosomal activity that breaks fibre-network of tenacious
sputum
AMBROXOL – (derivative of bromohexine)
DORNASE – alfa:
• Depolymerizes DNA of purulent airways secretions &
the viscosity of sputum.
• Given by nebulization.
Expectorants drugs:
GUAIFENESIN
Stimulates gastric mucosa (vagal receptors) which
initiate the reflex secretions of respiratory tract fluid.
