Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Pharm Exam 4 > Sulfonamides and Trimethoprim > Flashcards

Sulfonamides and Trimethoprim Flashcards

1
Q

First effective chemotherapeutic agent employed systemically for the prevention and cure of bacterial infections in man?

A

Sulfonamides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the important structural features of the sulfonamides?

A

Sulfamide (SO2) attached to a benzene ring and an amino group (NH2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What causes inactivation of the sulfonamide and how?

A

Hepatic metabolism of amino group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Are sulfonamides broad spectrum or narrow spectrum?

A

Broad spectrum (both Gram + and -)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Are sulfonamides bacteriostatic or bacteriocidal?

A

Bacteriostatic, so immune system is key for resolution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Instance when a sulfonamide can be bacteriocidal?

A

High concentration achieved in urine to treat UTI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

On what part of the bacteria will sulfonamide work in treating the UTI?

A

Effect cell’s ability to replicate by starving it of thymine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Sulfonamides are structural analogues to what compound?

A

Para aminobenzoic acid (PABA) so it’s a competitive inhibitor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why is PABA important to bacteria and why is its antagonism not toxic to humans?

A

Bacteria use PABA to make folic acid. We get our folic acid from our diet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is folic acid used for?

A

Synthesis of purines, pyrimidines, and proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Is there a delay in the effect of sulfonamides and why?

A

Yes, bacteria can use up folate pools before taking up sulfonamide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How can sulfonamide be bacteriocidal instead of its normal bacteristatic?

A

When it achieves high enough concentration to cause a thymine-less death by stopping DNA synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Sulfonamides are synergistic with what drug?

A

Trimethoprim

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Where does Trimethoprim work on the bacteria?

A

Still at folic acid, except it inhibits dihydrofolate reductase from transforming dihydrofolate to tetrahydrofolate, the carbon donor to proteins, DNA, & RNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What does Sulfamethoxazole and Trimethoprim do (SMZ/TMP)?

A

Sequential blockade of folic acid in bacteria (PABA—SMZ—>Dihydrofolic acid–TMP–> Tetrahydrofolic acid—–>DNA helper

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How can bacteria gain resistance to sulfonamides (4)? Note the primary method.

A
  1. Alter enzyme using PABA so it only uses PABA and not the sulfonamide
  2. Increase capacity to inactivate or destroy sulfonamide
  3. Alternative metabolic pathway for synthesis
    * 4. Increase PABA synthesis to outcompete the sulfonamide (primary)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Are sulfonamides soluble or insoluble?

A

Insoluble; transformed to soluble salts.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Character of gut absorption for Sulfonamide?

A

Rapid: 70-100% absorbed from oral

19
Q

Can Sulfonamides be given subcutaneously or intramuscular and why?

A

No, sulfonamide salts are highly alkaline

20
Q

2 specific uses of sulfonamides?

A

Opthalmic solutions/ointments due to good aqueous humor penetration
Meningitis (can cross BBB)

21
Q

How do sulfonamides travel in the blood and what does this mean for their activity?

A

Bound to plasma protein (displace bilirubin), only unbound drugs can enter the cell & act

22
Q

What is a toxicity that can occur with sulfonamide binding to plasma proteins?

A

They displace bilirubin that can then cross blood brain barrier and deposit in basal ganglion causing brain damage

23
Q

Distribution of Sulfonamides?

A

Uniform throughout body, crosses blood brain barrier and get into aqeous humor of eye

24
Q

How is Sulfonamide metabolized?

A

Hepatic at the amino group which eliminates the antibacterial, but keeps the toxicity

25
Q

How is Sulfonamide eliminated? What fluids have high and low concentrations?

A

In urine by filtration through the kidneys; has high concentration in intestinal juices (most reabsorbed) and low levels are in saliva, milk, and prostatic fluid

26
Q

Why is sulfonamide the drug of choice for a kidney infection?

A

Its excretion provides for levels 10-25 higher than that in serum

27
Q

Toxic effects from Sulfonamides?

A

GI intolerance, anorexia, nausea, vomiting

28
Q

2 major toxic effects of Sulfonamides

A

Hypersensitivity rash: Stevens-Johnson syndrome (loss of mucosal lining) in children could be fatal
Crystallization in kidneys

29
Q

Two ways to prevent sulfonamide crystallization in kidneys?

A

Maintain high urine ph (alkaline w/ NaHCO3) and high urine flow via high fluid intake (1.5-2L/day)

30
Q

What genetic deficiency will react with sulfonamides? What does this cause?

A

Glucose-6-phosphate dehydrogenase deficiency; acute hemolytic anemia

31
Q

What is a toxic effect sulfonamides will have on newborns?

A

Sulfonamide displaces bilirubin causing its deposit in brain leading to brain damage

32
Q

Is sulfonamide prescribed for oral dental lesions?

A

No. Used in UTI, topical infections (burns, eyes)

33
Q

What are six therapeutic uses for sulfonamides?

A

Pulmonary lesions, brain abscesses, joint infections, urinary tract infections (often 1st agent tried), systemic infections, topical infections (burn wounds, eye infections)

34
Q

What is a characteristic of sulfonamides that even if put with other sulfonamides they act as if they are alone in solution?

A

Principle of Independent solubility

35
Q

What does principle of independent solubility help with in Sulfonamide treatment?

A

Decreases risk of urine crystallization

36
Q

What does treating with 3 sulfonamide cocktail allow?

A

Can get higher therapeutic dose, while avoiding precipitating out in urine

37
Q

How does trimethoprim work?

A

Selective inhibitor of dihydrofolate reducatase in lower organism (has a higher affinity for the bacterial version of this enzyme–> in humans, a 20-60kx greater needed)

38
Q

When is trimethoprim bacteriostatic? Bacteriocidal?

A

Bacteriostatic: absence of all products of one-carbon metabolism
Bacteriocidal: Absence of thymine (but presence of purines and amino acids)

39
Q

Why does thymine play such a big role in trimethoprim?

A

“Thymineless death” causes unbalanced growth, killing the bacteria

40
Q

What two ways bacteria form resistance to trimethoprim?

A
  1. Increased levels of enzyme, dihydrofolate reductase

2. Reduced binding to trimethoprim to target enzyme

41
Q

What is one potential toxicity of trimethoprim?

A

To bone marrow progenitors causes suppression of blood cell production

42
Q

What is the half life of SMZ/TMP?

A

5-15 hours

43
Q

Where in the body is SMZ/TMP bacteriocidal?

A

Blood and urine due to low thymine [ ] (high amino acid content)

Pharm Exam 4 (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions