Veterinary Sulfonamides Administration
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Questions and Answers

What is the main reason for the continued widespread use of sulfonamides in veterinary medicine?

  • Their low cost and relative efficacy in common bacterial diseases (correct)
  • Their broad spectrum of activity against all bacterial diseases
  • Their high cost and wide availability
  • Their minimal side effects and long duration of action

    • What renders sulfonamides much more effective than sulfonamides alone?

  • Their combination with diaminopyrimidines (correct)
  • Their duration of effect
  • Their lipid solubility
  • Their water solubility

    • How often are standard-use sulfonamides typically administered in most species to control systemic infections due to susceptible bacteria?

  • Once a week
  • Every 1 to 2 days
  • Every 6 to 24 hours (correct)
  • Every 3 to 4 days

    • What is the primary use of very water-soluble sulfonamides like sulfisoxazole and sulfasomidine?

    <p>To treat urinary tract infections</p> Signup and view all the answers

    What is the most common route of administration for therapeutic doses of sulfonamides in monogastric animals?

    <p>Oral (PO)</p> Signup and view all the answers

    In which animals is the absorption of trimethoprim delayed and tends to be trapped in the ruminoreticulum?

    <p>Ruminants</p> Signup and view all the answers

    Where are concentrations of sulfadiazine ≥90% bound to plasma proteins?

    <p>In the kidneys</p> Signup and view all the answers

    Which body fluid may contain 50%–90% of the concentrations of sulfonamides found in blood?

    <p>Cerebrospinal fluid (CSF)</p> Signup and view all the answers

    Where are trimethoprim and ormetoprim likely to accumulate due to their basic properties?

    <p>In acidic urine</p> Signup and view all the answers

    What is the distribution pattern of sulfonamides based on?

    <p>The ionization state, vascularity of specific tissues, and barriers to diffusion</p> Signup and view all the answers

    What is the main route of excretion for trimethoprim?

    <p>Urine</p> Signup and view all the answers

    Which species shows some suggestion of extensive hepatic biotransformation for trimethoprim?

    <p>Ruminants</p> Signup and view all the answers

    Where are sulfonamide residues often detected due to passive diffusion?

    <p>Milk</p> Signup and view all the answers

    Which route of administration greatly decreases the bioavailability of sulfachlorpyridazine?

    <p>Oral (PO)</p> Signup and view all the answers

    What is the main route of administration for therapeutic doses of sulfonamides when dealing with acute life-threatening infections?

    <p>Intravenous (IV)</p> Signup and view all the answers

    Which tissue may have concentrations of trimethoprim higher than corresponding plasma concentrations?

    <p>Kidneys</p> Signup and view all the answers

    What is the effect of sulfonamides on ruminal microflora?

    <p>Sulfonamides depress the cellulolytic function of ruminal microflora</p> Signup and view all the answers

    What adverse effect has been associated with prolonged sulfonamide treatment in dogs?

    <p>Hypothyroidism</p> Signup and view all the answers

    How does high-dose trimethoprim treatment affect hematopoiesis?

    <p>Promotes maturation defects</p> Signup and view all the answers

    What adverse effect is associated with treatment using trimethoprim-sulfamethoxazole in horses?

    <p>Immune-mediated hemolytic anemia</p> Signup and view all the answers

    Which parameter is increased by sulfonamides according to the text?

    <p>Eosinophil count</p> Signup and view all the answers

    What is the effect of antacids on the gastrointestinal absorption of sulfonamides?

    <p>Inhibits absorption</p> Signup and view all the answers

    Which statement about withdrawal times for food-producing animals is true?

    <p>Attention to withdrawal times is essential due to adverse effects in people</p> Signup and view all the answers

    How does urinary acidification affect sulfonamide excretion?

    <p>Reduces sulfonamide excretion</p> Signup and view all the answers

    What type of wounds do sulfonamides retard healing of?

    <p>Uncontaminated wounds</p> Signup and view all the answers

    Which species may experience mild follicular thyroid hyperplasia due to prolonged administration of sulfonamides?

    <p>Dogs</p> Signup and view all the answers

    What is the potential effect of concurrent administration of acidic drugs with higher binding affinities on sulfonamides?

    <p>Decreased plasma-protein binding of sulfonamides</p> Signup and view all the answers

    How does alkalinization of urine affect sulfonamide excretion?

    <p>Promotes sulfonamide excretion</p> Signup and view all the answers

    What is the optimal in vitro ratio for the combination of trimethoprim or ormetoprim and a sulfonamide?

    <p>1:20</p> Signup and view all the answers

    Why do commercially available preparations use a ratio of 1:5 for the combination of trimethoprim or ormetoprim and a sulfonamide?

    <p>Due to pharmacokinetic considerations</p> Signup and view all the answers

    When are sulfonamides most effective?

    <p>In the early stages of acute infections</p> Signup and view all the answers

    What happens once the stores of folic acid, purines, thymidine, and amino acids are depleted?

    <p>Bacteriostasis occurs</p> Signup and view all the answers

    Why are adequate cellular and humoral defense mechanisms critical for successful sulfonamide treatment when used as sole agents?

    <p>To counteract the bacteriostatic nature of sulfonamides</p> Signup and view all the answers

    What is the most common mechanism of resistance to sulfonamides?

    <p>Increased affinity of altered proteins</p> Signup and view all the answers

    Why are sulfonamides less effective in purulent environments?

    <p>Due to increased concentration of PABA</p> Signup and view all the answers

    What is a common characteristic among all sulfonamides?

    <p>Cross-resistance between different species</p> Signup and view all the answers

    Which microorganisms are highly resistant to sulfonamides?

    Signup and view all the answers

    What is the main reason why a group of diaminopyrimidines is used in combination with sulfonamides?

    <p>To block microbial enzyme systems sequentially</p> Signup and view all the answers

    Which of the following best describes the effect of using diaminopyrimidines alone against bacteria?

    <p>Moderately effective and resistance develops rapidly</p> Signup and view all the answers

    What is the role of sulfonamides when used in combination with pyrimethamine to treat protozoal diseases?

    <p>Potentiate the effect of pyrimethamine</p> Signup and view all the answers

    What is the basis for the use of triple sulfonamide mixtures clinically?

    <p>Higher solubility compared to single drug at the same total concentration</p> Signup and view all the answers

    Which functional group substitution results in compounds with varying physical, chemical, pharmacological, and antibacterial properties?

    <p>Substitution on the amido group</p> Signup and view all the answers

    What happens to the solubility of N4-acetylated sulfonamides compared to their nonacetylated forms?

    <p>Decreases</p> Signup and view all the answers

    What is the pKa range for sulfonamides of therapeutic interest?

    <p>$4.8-8.6$</p> Signup and view all the answers

    How are water-soluble sodium or disodium salts of sulfonamides used for parenteral administration prepared?

    <p>As highly alkaline solutions</p> Signup and view all the answers

    How do diaminopyrimidines such as trimethoprim inhibit bacteria and protozoa?

    <p>By competitively inhibiting dihydrofolate reductase (DHFR)</p> Signup and view all the answers

    Which enzyme is facilitated by PABA as a substrate for the synthesis of dihydrofolic acid?

    <p>Dihydropterate synthetase (DPS)</p> Signup and view all the answers

    What does blockade of several enzymes needed for the biogenesis of purine bases result in?

    <p>Inhibition of growth and replication</p> Signup and view all the answers

    At what concentrations do sulfonamides exhibit a bactericidal action?

    <p>High concentrations found in urine</p> Signup and view all the answers

    What is the mechanism of action of potentiated sulfonamides?

    <p>Inhibition of folic acid synthesis</p> Signup and view all the answers

    What is the reason for commercially available preparations to use a ratio of 1:5 for the combination of trimethoprim or ormetoprim and a sulfonamide?

    <p>Pharmacokinetic considerations</p> Signup and view all the answers

    What is the primary reason for the lag period before the effects of sulfonamide treatment become evident?

    <p>Bacteria use existing stores of folic acid and other compounds</p> Signup and view all the answers

    What is the most common mechanism of resistance to sulfonamides?

    <p>Altered proteins with decreased affinity</p> Signup and view all the answers

    Why are sulfonamides less effective in purulent environments?

    <p>Release of PABA from decaying neutrophils</p> Signup and view all the answers

    What leads to bacteriostasis once the existing stores are depleted?

    <p>Depletion of folic acid, folinic acid, purines, thymidine, and amino acids</p> Signup and view all the answers

    What characteristic distinguishes potentiated sulfonamides from standard sulfonamides in terms of antibacterial efficacy?

    <p>Potentiated sulfonamides are bactericidal while standard sulfonamides are bacteriostatic</p> Signup and view all the answers

    What effect does overproduction of PABA have on the inhibition of dihydropterate synthetase?

    <p>Precludes inhibition of dihydropterate synthetase</p> Signup and view all the answers

    What is the main factor influencing the efficacy of sulfonamides?

    <p>Cellular and humoral defense mechanisms</p> Signup and view all the answers

    What is the primary factor determining the antibacterial efficacy of potentiated sulfonamides?

    <p>Concentration at the site of infection</p> Signup and view all the answers

    What renders potentiated sulfonamides time dependent in their antibacterial efficacy?

    <p>Bacteriostatic nature</p> Signup and view all the answers

    What leads to an optimal ratio for the combination of trimethoprim or ormetoprim and a sulfonamide at the site of infection?

    <p>Pharmacokinetic considerations</p> Signup and view all the answers

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