HES 033: General Pharmacology - Sulfonamides

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Questions and Answers

What must happen to the dosage of sulfonamide in patients with renal failure?

  • It must be reduced. (correct)
  • It must remain unchanged.
  • It must be increased for better efficacy.
  • It must be discontinued.

Which drug combination is the first-line treatment for acute toxoplasmosis?

  • Dihydrofolate reductase alone
  • Sulfadiazine and pyrimethamine (correct)
  • Sulfadoxine and pyrimethamine
  • TMP-SMZ

Which of the following infections is TMP-SMZ primarily indicated for?

  • Pneumocystis jiroveci pneumonia (correct)
  • Influenza
  • Tuberculosis
  • Bacterial meningitis

What defines sulfadoxine in the context of malaria treatment?

<p>It is a long-acting sulfonamide. (C)</p> Signup and view all the answers

What is the role of dihydrofolate reductase in the context of pyrimethamine treatment?

<p>It is inhibited by pyrimethamine. (D)</p> Signup and view all the answers

What conditions can TMP-SMZ be used to treat, besides pneumonia?

<p>Toxoplasmosis and nocardiosis (C)</p> Signup and view all the answers

In treating malaria, what is the combination of sulfadoxine and pyrimethamine commonly referred to?

<p>Fansidar (B)</p> Signup and view all the answers

Which of the following conditions requires the use of sulfonamide as a second-line treatment?

<p>Malaria (A)</p> Signup and view all the answers

What is the primary mechanism by which sulfonamides exert their antibacterial effect?

<p>They inhibit dihydropteroate synthase. (A)</p> Signup and view all the answers

Which feature is true about the solubility of sulfonamides?

<p>They are more soluble at alkaline pH. (B)</p> Signup and view all the answers

What is the effect of bacterial mutations on the effectiveness of sulfonamides?

<p>They can lead to PABA overproduction. (C)</p> Signup and view all the answers

Which of the following categories includes sulfonamides that can be absorbed orally?

<p>Oral absorbable sulfonamides (B)</p> Signup and view all the answers

Which of the following combinations provides synergistic activity with sulfonamides?

<p>Sulfonamide and a dihydrofolate reductase inhibitor (D)</p> Signup and view all the answers

How does the protein binding of sulfonamides vary?

<p>It can range from 20% to over 90%. (D)</p> Signup and view all the answers

What type of bacteria do sulfonamides primarily inhibit?

<p>Both gram-positive and gram-negative bacteria (A)</p> Signup and view all the answers

Which of the following statements is true regarding the action of sulfonamides?

<p>They are bacteriostatic. (B)</p> Signup and view all the answers

What is a primary adverse effect associated with sulfonamides that can lead to obstruction in the urinary tract?

<p>Crystalluria (D)</p> Signup and view all the answers

Which topical sulfonamide is specifically mentioned as being effective for bacterial conjunctivitis?

<p>Sodium sulfacetamide (C)</p> Signup and view all the answers

Which condition can be triggered by the absorption of mafenide acetate from burn sites?

<p>Stevens-Johnson syndrome (C)</p> Signup and view all the answers

What complication may occur due to the use of sulfonamides in pregnant patients?

<p>Kernicterus (D)</p> Signup and view all the answers

Which of the following sulfonamides may slow the healing of burn wounds?

<p>Silver sulfadiazine (A)</p> Signup and view all the answers

What treatment is suggested for crystalluria caused by sulfonamides?

<p>Administer sodium bicarbonate to alkalinize urine (A)</p> Signup and view all the answers

Which group of patients is at risk for hemolytic reactions when taking sulfonamides?

<p>Patients with glucose-6-phosphate dehydrogenase deficiency (B)</p> Signup and view all the answers

Which of the following is a sulfonamide that is used in treating inflammatory bowel disorders?

<p>Sulfasalazine (B)</p> Signup and view all the answers

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Study Notes

Sulfonamides Overview

  • Structural analogs of p-aminobenzoic acid (PABA), influencing their pharmacological properties.
  • Sulfonamides are synthesized by modifying the sulfanilamide nucleus with various substituents.
  • More soluble at alkaline pH; prepared as sodium salts for intravenous use.

Mechanism of Action

  • Act as competitive inhibitors of dihydropteroate synthase, blocking folate synthesis crucial for nucleic acid production.
  • Resistance arises from bacterial mutations leading to PABA overproduction, changes in target enzyme affinity, or impaired drug permeability.

Classification of Sulfonamides

  • Oral absorbable sulfonamides: Absorbed in the stomach and small intestine; distributed widely including CNS.
  • Non-absorbable and topical agents: Include treatments for localized infections.

Clinical Applications

  • Fixed-drug combination TMP-SMZ is effective against Pneumocystis jiroveci pneumonia and other infections.
  • First-line treatment for acute toxoplasmosis: sulfadiazine with pyrimethamine.
  • Long-acting sulfadoxine combined with pyrimethamine is a second-line choice for malaria.
  • Sulfasalazine is used for inflammatory bowel disorders, while topical agents like sodium sulfacetamide treat conjunctivitis.

Adverse Effects

  • Risk of crystalluria, hematuria, or renal obstruction due to precipitate formation.
  • Potential for hemolytic reactions in G6-PD deficiency patients.
  • Increased risk of kernicterus in newborns if taken late in pregnancy.

Notable Sulfonamide Drugs

  • Sulfisoxazole, Sulfamethizole, Sulfacytine, Sulfamethoxazole, Sulfasalazine, Sodium Sulfacetamide, Mafenide, Sulfadiazine, Sulfapyridine, Sulfadoxine.

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