Antimetabolites: Sulfonamides & Trimethoprim

Question 1

regarding sulfonamides, explain MOA, therapeutic uses, adverse effects

Answer 1

MOA: bacteriostatic–so need adequate host defenses. suppress bacterial growth by inhibiting synthesis of tetrahydrofolate, a derivative of folic acid. Folate is required by all cells to make DNA, RNA, and proteins.

therapeutic uses: UTIs, nocardiosis, listeria infection, infections caused by C. trachomatis.

adverse effects;
hypersensitivity reactions: rash, drug fever, photosensitivity (avoid by no sunlight, long clothes, apply sunscreen).
most severe is steven-johnson syndrome: widespread lesions of the skin and mucous membranes combined with fever, malaise, and toxemia. mortality rate 25%, most common in long acting sulfonamides, which are now banned in the US.

Question 2

regarding trImethoprIm, explain mechanisms of action, therapeutic uses, adverse effects.

Answer 2

MOA: inhibits DIhydrofolate reductase (stops the addition of hydrogens), the enzyme needed to convert dihydrofolic acid to it’s active form, tetrahydrofolic acid. No folic acid, no DNA/RNA/Protein synthesis.

therapeutic uses: only for initial therapy of acute, uncomplicated UTIs.

AE’s: megaloblastic anemia, thrombocytopenia, neutropenia–these occur ONLY in individuals with pre-existing folate deficiency.

Question 3

state the advantages of the TMP/SMZ combination drug in terms of MOA and therapeutic uses

Answer 3

MOA: inhibiting consecutive steps in he synthesis of tetrahydrofolic acid. Reduced ability of target organism to make nucleic acids and proteins.

therapeutic uses: UTIs, pneumocystis pneumonia, GI infections (gram negative)

Question 4

list patient teaching points for sulfonamides and trimethoprim

Answer 4

complete treatment course
dc drug use and notify a provider at the first sign of hypersensitivity (rash)
avoid prolonged exposure to sunlight, long clothes, apply sunscreen to exposed skin
consume 8-10 glasses of water per day
inform patients about early signs of blood disorders (sore throat, fever (pallor easy bruising or bleeding), and instruct them to notify the provider if these occur.

Question 5

describe drug treatment protocol for acute cystitis and UTIs, using trimethoprim as a first line drug

Answer 5

3 days if uncomplicated, 7 days if complicated.

Question 6

labs to watch with these drugs

Answer 6

K+ for trimethoprim (d/t possible hyperkalemia)

check K+ four days into tx

Question 7

define the conditions:

acute uncomplicated pyelonephritis, complicated UTI, recurrent UTI

Answer 7

pyelonephritis: inflammation of the substance of the kidney as a result of bacterial infection.

acute uncomplicated pyelonephritis: Acute pyelonephritis is considered uncomplicated if the infection is caused by a typical pathogen in an immunocompetent patient who has normal urinary tract anatomy and renal function

complicated UTI: A complicated urinary tract infection (UTI) is a term to describe a UTI that doesn’t respond to traditional treatments. This may be due to underlying medical conditions or other risk factors, such as age and anatomical differences.

recurrent UTI: Recurrent urinary tract infection (UTI) refers to ≥2 infections in six months or ≥3 infections in one year.