Pharm - Acetaminophen, Penicillin

Question 1

How does it work?

Answer 1

Inhibits COX-3 pathway by competing with COX enzyme for the active site on arachidonic acid. Thereby, blocking prostaglandin synthesis in the CNS.

Question 2

What symptoms does COX-3 bring about?

Answer 2

Pain and fever (NOT inflammation)

Question 3

Contraindications for acetaminophen:

Answer 3

• History of liver disease (including alcoholism)

- Kawasaki’s (can cause coronary aneurysm)

Question 4

What is it a good substitute for and why?

Answer 4

• Substitute for aspirin and other NSAIDs as an analgesic and antipyretic for patients with GI complaints, coagulopathy, and renal contraindications
• Does not effect COX-1 (which affects GI, Renal, Platelet f(x), Homeostatic f(x), and Macrophage differentiation)

Question 5

Adverse effects?

Answer 5

• Hepatic damage (acet. NAPQI reduces glutathiol to toxic byproducts)
• Therapeutic doses -> possible increase in hepatic enzymes
• Large doses -> dizziness, excitement, disorientation, LFT abnormalities
• Overdose - liver necrosis, ART necrosis

Question 6

Mechanism of Action?

Answer 6

• Acts on CNS
• Reversibly inhibits COX-3 by competing with COX enzyme for active site on arachidonic acid -> blocks fm of prostaglandins -> inhibits endogenous pyrogens action on heat reg. ctrs in hypothalamus
• Reduces pain and fever (by blocking PG fm.)

Question 7

Prostaglandin:

Answer 7

• Local hormone produced by almost all tissues

- Pro-inflammatory, pain, and fever

Question 8

Arachidonic Acid:

Answer 8

• Main precursor for PGs
• Formed from phospholipids (cell membrane)
• Synthesized into eicosanoids (defense molecules) via COX (cyclooxygenase) or LOX (lipooxygenase)

Question 9

COX-1:

Answer 9

• Isoenzyme of COX in most body tissues
• Produces prostanoids -> affects GI (stomach lining and acid prod.), vascular homeostasis, platelet aggregation (thromboxane A2), renal f(x)

Question 10

COX-2:

Answer 10

• Isozyme active/induced at site of inflammation

- Inhibited by glucocorticoids

Question 11

COX-3:

Answer 11

• Isozyme encoded by COX-1
• Expressed in the brain
• Weak involvement in inflammation (Think Pain and Fever!)

Question 12

Classifications for acetaminophen:

Answer 12

Paracetamol, N-acetyl-P-aminophenol, Tylenol

Question 13

What is Penicillin VK?

Answer 13

Phenoxymethylpenicillin w/Potassium (ORAL FORM)

Question 14

Classification of Penicillin?

Answer 14

b-lactam antibiotic

Question 15

Indications for Penicillin?

Answer 15

Tx for gram-positive bacterial infection (resp. tract, otitis media, sinusitis, rheumatic fever prophylaxis)

Question 16

Contraindications for penicillin?

Answer 16

Hypersensitivity/allergy to penicillin or any component of the drug

Question 17

Adverse effects for penicillin?

Answer 17

> 10%: melanoglossia (black/furry tongue), mild diarrhea, nausea, yeast infection (mouth/vaginal), vomiting
1%: Exfoliative dermatitis, interstitial nephritis

Question 18

MOA for penicillin?

Answer 18

Prevents synthesis of bacterial peptidoglycan layer (binds to penicillin-binding protein on bacteria) -> lysis
-Also activates autolysin activity -> lysis

Question 19

How does resistance to Penicillin form?

Answer 19

• B-lactamase production -> destroys b-lactam ring on penicillin
• Reduction/alteration of PBPs -> decrease in active sites for penicillin
• Failure to activate autolysin
• Alternate forms of bacterial cell wall -> no peptidoglycan to affect

Question 20

What are some ways to fight back against Penicillin resistance?

Answer 20

• Clavulanic acid, Sulbactam, Tazobactum
• > Contain same b-lactam ring
• > Out-compete penicillin for b-lactamase
• > Penicillin not destroyed and can be effective