Penicillin - Noha AI

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Questions and Answers

What type of formulation is benzathine penicillin marketed as?

  • Dry powder for reconstitution (correct)
  • Liquid formulation with water additives
  • Ready-to-use liquid solution
  • Stable aqueous suspension ready for use

At what pH level is a ready injection most stable according to its formulation?

  • 4-6
  • 9-11 (correct)
  • 12-14
  • 7-9

What can accelerate the degradation of antibiotics when mixed with other drugs?

  • Admixture with acidic drugs (correct)
  • Reconstitution with neutral pH solutions
  • Use of alkaline solutions
  • Dilution with sterile water

What is a characteristic of procaine penicillin's formulation?

<p>Is available as a stable aqueous suspension (C)</p> Signup and view all the answers

What is the consequence of an admixture of antibiotics with acidic drugs?

<p>Accelerates degradation of antibiotics (B)</p> Signup and view all the answers

Which condition describes an injection that must be reconstituted with sterile water before use?

<p>Benzathine penicillin (C)</p> Signup and view all the answers

Which characteristic of lipid-soluble drugs contributes to their better penetration through capillaries?

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

What is a recommended practice regarding the dilution of a substance with NaCl in a medical context?

<p>It should only be used directly in a canula. (B)</p> Signup and view all the answers

Which of the following oral antimicrobial agents is mentioned as having 100% bioavailability at IV levels?

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

What is a potential consequence of administering high oral doses of certain antimicrobial medications?

<p>Toxicity in the gastrointestinal tract (A)</p> Signup and view all the answers

Which factor does NOT influence the formulation of oral antimicrobials?

<p>Price of the medication (C)</p> Signup and view all the answers

Which of the following statements about routes of administration is false?

<p>All drugs administered orally achieve 100% bioavailability. (B)</p> Signup and view all the answers

What is a crucial consideration when deciding on the route of antimicrobial administration?

<p>Risk of gastrointestinal toxicity from overdosing (B)</p> Signup and view all the answers

Which type of drugs is generally less effective at penetrating capillaries compared to lipid-soluble drugs?

<p>Water-soluble drugs (B)</p> Signup and view all the answers

What is the best predictor of activity for certain antimicrobial agents (AMs)?

<p>Area under the concentration-time curve to minimum inhibitory concentration (AUC/MIC) (B)</p> Signup and view all the answers

Which type of antimicrobial activity is associated with a ratio of peak concentration to minimum inhibitory concentration (Cmax/MIC)?

<p>Concentration-dependent activity (C)</p> Signup and view all the answers

Which pharmacokinetic parameter is important for defining the response to antimicrobial treatment?

<p>Duration the drug concentration remains above MIC (C)</p> Signup and view all the answers

What determines whether an antimicrobial is time-dependent or concentration-dependent?

<p>The specific characteristics of the antimicrobial agent (B)</p> Signup and view all the answers

What does MIC stand for in the context of pharmacodynamics?

<p>Minimum Inhibitory Concentration (A)</p> Signup and view all the answers

Which statement is true regarding the relationship between antimicrobial drug treatments and bacterial sensitivity?

<p>Combination of pharmacokinetic parameters and bacterial sensitivity defines treatment response. (D)</p> Signup and view all the answers

What primarily determines the height of the peak plasma drug level in intravenous administration?

<p>The rate of IV infusion and dose size (C)</p> Signup and view all the answers

Why is bolus administration preferred for achieving peak plasma drug levels?

<p>It achieves the highest concentration in a shorter duration. (C)</p> Signup and view all the answers

What occurs when the rate of IV infusion is slowed?

<p>Lower drug concentrations and increased elimination. (C)</p> Signup and view all the answers

What is a consequence of rapid IV administration in severe infections?

<p>Rapid increase in peak concentration. (A)</p> Signup and view all the answers

What process is primarily affected by the variable rate of drug administration?

<p>Rate of drug absorption into tissues. (D)</p> Signup and view all the answers

Which factor does NOT influence peak plasma drug levels?

<p>The drug's molecular structure. (B)</p> Signup and view all the answers

In the context of pharmacokinetics for severe infections, what does 'Cmax' refer to?

<p>The peak concentration of the drug in plasma. (D)</p> Signup and view all the answers

What is the likely impact of choosing a slower infusion rate for a drug?

<p>Prolonged duration of therapeutic effect. (A)</p> Signup and view all the answers

What does the term 'volume of distribution' signify in pharmacokinetics?

<p>The space that the drug occupies within the body. (B)</p> Signup and view all the answers

Why might a healthcare provider choose bolus administration over continuous infusion?

<p>It achieves a quick therapeutic effect at high concentrations. (C)</p> Signup and view all the answers

Flashcards

Procaine penicillin

A stable aqueous penicillin suspension, ready for use.

Benzathine penicillin

A dry penicillin powder that needs reconstitution with sterile water.

Antibiotic stability

How long an antibiotic stays effective.

Acid-catalyzed hydrolysis

Breaking down penicillin in acidic environments.

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Oral antibiotic formulation

How antibiotics are made for swallowing.

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Oral bioavailability

The amount of antibiotic that reaches the bloodstream after taking orally.

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Peak plasma drug level

The highest concentration of a drug in the blood.

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Bolus administration

Giving a drug quickly in a single dose.

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Time-dependent activity

How long an antibiotic stays above a certain level to be effective.

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Concentration-dependent activity

How the drug's peak concentration affects its effectiveness.

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Minimum inhibitory concentration (MIC)

The smallest drug concentration that stops bacterial growth.

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AUC/MIC ratio

A measure of antibiotic effectiveness.

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Post-antibiotic effect (PAE)

Extended bacterial growth suppression after drug removal.

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Aminoglycosides

A type of antibiotic with a long PAE.

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β-lactam antibiotics

Antibiotics with little to no PAE against Gram-negatives.

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Antimicrobial Distribution

How an antibacterial moves from the blood to the infection.

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Lipid solubility

Ability of a drug to dissolve in fats.

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Tissue Concentration

Drug concentration at the infected area.

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IV Antimicrobials

Antimicrobials delivered intravenously.

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Infusion rate

Rate at which a drug is infused.

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Volume of distribution

The volume the drug appears to be spread in.

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Elimination rate

Rate at which the body removes the drug.

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Lipophilicity

The tendency of a molecule to dissolve in fat.

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Extravascular infections

Infections outside the blood vessels.

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Tissue-related factors

Aspects of tissues influencing drug distribution.

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Study Notes

Penicillin Formulation

  • Procaine penicillin is a stable aqueous suspension, ready for use
  • Benzathine penicillin is a dry powder for reconstitution with sterile water before use

Antibiotic Stability

  • Ready injection formulations are most stable at their formulated pH
  • Mixing antibiotics with other drugs can accelerate degradation
  • Acid-catalyzed hydrolysis of penicillins is accelerated by acidic drugs

Routes of Administration

  • Oral antimicrobial (PO) formulation is dependent on solubility, acid stability, and lipophilicity
  • Lipid-soluble drugs penetrate capillaries better than water-soluble drugs
  • Oral bioavailability varies significantly between antibiotics
  • Some antibiotics have 100% bioavailability like fluoroquinolones, tetracycline, metronidazole, and rimethoprim-sulfamethoxazole
  • High oral doses can lead to excessive GI tract toxicity

Pharmacokinetics of IV Antimicrobials

  • Peak plasma drug level is determined by infusion rate, dose size, volume of distribution, and elimination rate
  • Bolus administration results in higher peak plasma levels due to shorter infusion time
  • Slowing infusion rate allows drug distribution and elimination, resulting in lower peak levels

Time- vs Concentration-Dependent Activity

  • Time-dependent activity correlates with drug concentration remaining above MIC (minimum inhibitory concentration)
  • Concentration-dependent activity correlates with the ratio of peak concentration to MIC
  • AUC/MIC ratio can also predict activity
  • The type of activity depends on the specific antimicrobial

Post Antibiotic Effect (PAE)

  • PAE is species and drug dependent
  • Aminoglycosides, metronidazole, and fluoroquinolones exhibit pronounced PAE
  • β-Lactam antibiotics have little to no PAE against Gram-negative organisms
  • PAE influences dosing schedules:
    • Long PAE allows for less frequent dosing
    • Short or no PAE may require continuous infusion

Antimicrobial Distribution

  • Most infections are extravascular, requiring antimicrobial movement from the bloodstream
  • Drug distribution is influenced by tissue-related factors (perfusion, vascular surface area, tight junctions) and drug-related factors (lipid solubility, molecular size, pKa, and protein binding)
  • Tissue concentration can be similar to, lower than, or greater than blood concentration
  • Tissue effectiveness may diverge from blood concentration predictions

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