Pharmacology Core Concepts: Drug Actions and Clinical Uses

Key Pharmacological Points

1. Paracetamol’s Antipyretic Action

Paracetamol’s antipyretic activity involves inhibiting COX-3.

2. NSAIDs vs. Opioids: Key Differences

(Information on differences not provided in the source text.)

3. COX-2 Inhibitors: Cardiovascular Risks

(Explanation for why cardiovascular adverse reactions occur with selective COX-2 inhibitors not provided in the source text.)

4. NSAID Contraindication: Gastric Ulcer

A contraindication for Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) is a gastric ulcer.

5. Oral Second-Generation Cephalosporins

Examples of oral second-generation cephalosporins include:

• Cefaclor
• Cefuroxime

6. Oral Penicillin: Penicillin V

An example of an oral penicillin is Penicillin V.

7. Imipenem-Cilastatin: Renal Protection

Cilastatin is combined with Imipenem because it inhibits renal dehydropeptidase I, preventing Imipenem’s renal degradation.

8. Intramuscular Penicillin: Benzathine

An example of an intramuscular penicillin is Benzathine penicillin.

9. Carbapenems: Action Mechanism

Carbapenems inhibit bacterial cell wall synthesis and have a high affinity for Penicillin-Binding Proteins (PBPs).

10. Drugs Active Against Anaerobes

An example of a drug with activity against anaerobic bacteria is the third-generation cephalosporin Ceftazidime. (Note: Anaerobic coverage of Ceftazidime can be limited; other agents are often preferred for significant anaerobic infections.)

11. Parenteral Vancomycin: Non-Indications

Parenteral vancomycin is generally not indicated for pseudomembranous colitis (for which oral vancomycin is used).

12. Gram-Negative Resistance Mechanisms

Mechanisms of resistance in Gram-negative bacteria to antibiotics (e.g., macrolides, or aminoglycosides like streptomycin as mentioned in original context) can include:

• Peptidyl mutations
• ARNT (as per original text, specific enzyme type or mechanism unclear)
• Esterases
• Bacterial phosphorylases

13. Macrolide for H. Pylori: Clarithromycin

Clarithromycin is a macrolide used in the eradication of Helicobacter pylori.

14. Clarithromycin: Pediatric Dosage

The pediatric dosage for Clarithromycin is 7.5 mg/kg every 12 hours.

15. IV Aminoglycosides: Safe Administration

When administering intravenous (IV) aminoglycosides, dilute in 50-100 mL of solution and infuse over 30 minutes to avoid neuromuscular blockade.

16. Trimethoprim-Sulfamethoxazole: MOA

The mechanism of action for Cotrimoxazole (Trimethoprim-Sulfamethoxazole) involves:

• Sulfamethoxazole: Competitively inhibits dihydropteroate synthase, interfering with para-aminobenzoic acid (PABA) utilization.
• Trimethoprim: Inhibits dihydrofolate reductase.

17. Cotrimoxazole: Pregnancy Category C

Cotrimoxazole is classified as Pregnancy Category C.

18. Cotrimoxazole: Prophylaxis for PJP

Cotrimoxazole is indicated for the prevention of Pneumocystis jirovecii pneumonia (PJP) (formerly Pneumocystis carinii pneumonia) in patients with AIDS.

19. Quinolones: Antacid Interaction

Antacids containing magnesium and aluminum can reduce the absorption of quinolones. The source text specifies this includes reduction of parenteral absorption, though this interaction predominantly affects oral absorption.

20. TB Prophylaxis: Isoniazid Intolerance

For tuberculosis (TB) prophylaxis in individuals who cannot tolerate Isoniazid, Rifampicin 600mg can be used.

21. Kanamycin Derivatives

Derivatives of Kanamycin include:

• Amikacin
• Dibekacin

22. Pseudomonas: Aminoglycoside Combinations

For Pseudomonas infections, justified aminoglycoside combinations include:

• a) Antipseudomonal penicillins and an aminoglycoside for serious infections with Pseudomonas aeruginosa.
• b) Antipseudomonal penicillins or cephalosporins with an aminoglycoside for empirical therapy in immunocompromised patients.

23. Aminoglycoside Resistance: Enzymes

Mechanisms of resistance to aminoglycosides include enzymatic modification by:

• Adenyltransferases
• Nucleotidyltransferases
• Phosphotransferases

These enzymes catalyze changes in the aminoglycoside structure, inactivating the drug.

24. Gentamicin: Pregnancy Category C

Gentamicin is classified as Pregnancy Category C. (Note: Often considered Category D, especially in later pregnancy, due to potential ototoxicity and nephrotoxicity in the fetus.)

25. Adult Amebiasis: Secnidazole Treatment

The most appropriate treatment for adult amebiasis (intestinal) can be Secnidazole 2g as a single dose.

26. Adult Trichomoniasis: Drug Therapy

(Specific drugs for adult trichomoniasis treatment not listed in this entry.)

27. Amebic Liver Abscess: Metronidazole

The most appropriate treatment for amebic liver abscess is Metronidazole 750mg three times daily (TID) for 5-10 days.

28. Adult Ascariasis: Mebendazole, Albendazole

Treatment for ascariasis in adults includes Mebendazole and Albendazole.

29. Benzimidazoles: Action Mechanism

(Mechanism of action for benzimidazoles not detailed in this entry.)

30. Fluconazole: QT Prolongation Interactions

Fluconazole can interact with other drugs, potentially increasing the risk of QT prolongation. Examples of interacting drugs mentioned include:

• Probenecid (increases fluconazole concentration)
• Astemizole (risk of QT prolongation)
• Terfenadine (implied by “TERB”, risk of QT prolongation)

31. Polyene Antibiotics: Examples

Examples of polyene antibiotics include:

• Natamycin
• Nystatin
• Amphotericin B

32. Terbinafine Cream: Topical Uses

Terbinafine 1% topical cream is used 1-2 times daily for various fungal infections:

• Tinea corporis/cruris and cutaneous candidiasis: 1-2 weeks
• Pityriasis versicolor: 2 weeks
• Tinea pedis: 2-4 weeks

33. Amphotericin B: Reducing Toxicity

To diminish the toxic effects of Amphotericin B, the following may be administered:

• Hydrocortisone 50 mg.
• Heparin 5 mg if using a peripheral IV route (if a central line is used, heparin may not be necessary).
• Potassium supplementation (100-200 mEq/day) is recommended to prevent hypokalemia.

34. Trypanosomiasis: First-Choice Drug

A first-choice drug for Trypanosomiasis is Pentamidine. (Note: Choice depends on the species of Trypanosoma and stage of the disease.)

35. Nystatin: Pediatric Dosage

The dosage of Nystatin in children is 200,000 Units, 4 times daily.

36. Resistant P. Falciparum: Mefloquine

For treating multidrug-resistant Plasmodium falciparum malaria, Mefloquine can be employed.

37. Ketoconazole: Dermatophyte Tx Duration

(Duration of Ketoconazole treatment for dermatophyte infections not specified in this entry.)

38. HIV Protease Inhibitor: Indinavir

An example of an anti-HIV drug from the protease inhibitor family is Indinavir.

39. Lamivudine: Adult and Pediatric Dosing

The dosage of Lamivudine is:

• Adults: 150mg every 12 hours.
• Children: 4 mg/kg every 12 hours.

40. Cutaneous Leishmaniasis: First Drug

The first-choice drug for cutaneous leishmaniasis is Meglumine Antimoniate.

41. Chlorhexidine: Key Feature – Adherence

A salient feature of Chlorhexidine is its ability to adhere to tissues (substantivity), providing prolonged antimicrobial effect.

42. Iodine Solutions: Antimicrobial Spectrum

Iodine solutions have a broad spectrum of activity, effective against:

• Viruses
• Bacteria
• Fungi
• Protozoa
• Parasites
• Spores

43. Aminopenicillins: Amoxicillin, Ampicillin

Examples of aminopenicillins include:

• Amoxicillin
• Ampicillin