Pharmacology Antimicrobials

Question 1

Treatment regime for common cold (acute rhinitis)

Answer 1

Symptomatic:

-NSAIDs and/or paracetamol
-Nasal Decongestant ( a1- adrenergic agonist)

Question 2

Nasal decongestants used for acute rhinits

Answer 2

Phenylephrine (short-acting)
Oxymetazoline (longer-acting)

Question 3

Cautions with Intranasal α1-adrenergic agonists?

Answer 3

rebound nasal congestion (rhinitis medicamentosa).
When used for more than 3 days

Question 4

Treatment of Allergic Rhinitis

Answer 4

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

Question 5

Topical intranasal antihistamine for Allergic Rhinitis

Answer 5

Azelastine

Question 6

Intranasal corticosteroids for Allergic Rhinitis

Answer 6

Beclomethasone
Bbbudesonide

Question 7

Empiric antimicrobial therapy for Acute bacterial sinusitis

Answer 7

Amoxycillin + Clavulanic acid

Question 8

Moa of Amoxycillin

Answer 8

Inhibits bacterial transpeptidases ⇒ inhibit crosslinking & cell wall synthesis⇒ lysis & cell death

Question 9

Examples of β-Lactamase Inhibitors

Answer 9

Clavulanic acid (with amoxycillin & ticarcillin)
Sulbactam (combined with ampicillin)

Tazobactam (combined with piperacillin)

Question 10

Cephalosporins drugs

Answer 10

1st generation: Cephalexin
2nd generation: Cefaclor
3rd generation: Ceftazidime

Question 11

Pharyngitis/Tonsillitis: Antibiotics regimen

Answer 11

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

Question 12

Macrolides drugs

Answer 12

❑ Erythromycin

❑Clarithromycin

❑ Azithromycin

Question 13

Moa of Macrolides

Answer 13

Bind 50S subunits of bacterial ribosomes & inhibit protein synthesis

Question 14

Uses of macrolides

Answer 14

-Penicillin-sensitive (allergic) patients

– Infections caused by mycoplasma, legionella & chlamydial

– Clarithromycin: Infections (M avium complex, H. pylori)

Question 15

Tetracyclines drugs

Answer 15

❑ Doxycycline

❑ Tigecycline

Question 16

MoA of Tetracyclines

Answer 16

Bind 30 S subunits of bacterial ribosomes & inhibit protein synthesis

Question 17

PK of Tetracyclines

Answer 17

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

Question 18

Uses of Tetracyclines

Answer 18

Infections caused by gram-positive/negative bacteria, rickettsiae,
chlamydiae, legionella, and mycoplasms

• Tigecycline: Multidrug resistant organisms such as MRSA, VREF, PRE

Question 19

ADRs of Tetracyclines

Answer 19

• 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

Question 20

Tetracyclines Contraindications:

Answer 20

▪ Pregnancy
Risk of hepatotoxicity in the mother
Teratogenicity

▪ Young children (< 8 years)

Discoloration of teeth & inhibition of bone growth in children

Question 21

Otitis externa treatment regimen

Answer 21

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)

Question 22

Alternatives for Amoxicillin+clavulanic acid for Otitis media

Answer 22

Cefuroxime, Cefaclor, Macrolides

Question 23

Bronchitis treatment regimen

Answer 23

Treatment: largely symptomatic
• Consider antimicrobials if:
• Pertussis (whooping cough)
Use a macrolide

Question 24

Anti-influenza drugs

Answer 24

Adamantane derivatives:
Amantadine

Neuraminidase inhibitors:
Oseltamivir: Prodrug given orally
Zanamivir (inhalation)

Question 25

Amantadine MOA:

Answer 25

Block the M2 proton ion channel of the virus particle and inhibit uncoating of the viral RNA (influenza A) thus preventing their replication

Question 26

Neuraminidase inhibitors MOA:

Answer 26

Inhibit neuraminidase, thereby prevent the release of new virions and their spread from cell to cell

Question 27

ADRs of NA inhibitors

Answer 27

GI discomfort and nausea (oseltamivir) Cough and bronchospasm (zanamivir) Caution: Asthma & COPD (zanamivir)

Question 28

Pneumonia: Treatment

Answer 28

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)

Question 29

HAP Pneumonia: Treatment

Answer 29

Pseudomonas: Ceftazidime + Fluoroquinolone, Imipenem MRSA: Vancomycin, Linezolid, Ceftaroline Aspiration pneumonia: Beta-lactam/beta-lactamase inhibitor or clindamycin or metronidazol plus amoxicillin.

Question 30

COVID-19: Specific Therapy

Answer 30

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

Question 31

ANTI TUSSIVES Drugs

Answer 31

(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

Question 32

MUCOLYTICS drugs

Answer 32

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.

Question 33

Expectorants drugs:

Answer 33

GUAIFENESIN Stimulates gastric mucosa (vagal receptors) which initiate the reflex secretions of respiratory tract fluid.