PTCB Pharmacology #2 3 Flashcards

Which of the following best describes a drug's "half-life"?

Answer: Time required for the plasma drug concentration to decrease by 50%

Half-life (t½) is the time required for the plasma concentration of a drug to decrease by 50%. It determines dosing frequency — drugs with short half-lives require more frequent dosing.

Fluoroquinolone antibiotics (e.g., ciprofloxacin) work by:

Answer: Inhibiting DNA gyrase and topoisomerase IV

Fluoroquinolones inhibit DNA gyrase (topoisomerase II) and topoisomerase IV, enzymes essential for bacterial DNA replication, repair, and transcription.

A drug's "volume of distribution" (Vd) indicates:

Answer: The extent to which the drug distributes throughout the body relative to plasma

Volume of distribution (Vd) is a theoretical volume that relates plasma concentration to total drug in the body. A high Vd indicates extensive tissue distribution (lipophilic drugs); a low Vd indicates drug stays in plasma.

Which of the following is a tetracycline antibiotic?

Answer: Doxycycline

Doxycycline is a tetracycline antibiotic that inhibits protein synthesis by binding to the 30S ribosomal subunit. It is used for atypical pneumonia, Lyme disease, acne, and malaria prophylaxis.

Which of the following drug classes are typically used as "rescue" medications for acute asthma attacks?

Answer: Short-acting beta-agonists (SABA)

Short-acting beta-agonists (SABAs) like albuterol are quick-relief/rescue medications for acute asthma. Inhaled corticosteroids are controller/maintenance therapy; LABAs are never used as monotherapy or rescue.

Macrolide antibiotics (e.g., azithromycin) work by:

Answer: Inhibiting protein synthesis by binding the 50S ribosomal subunit

Macrolides bind the 50S ribosomal subunit, blocking translocation and inhibiting bacterial protein synthesis. They are used for atypical pneumonia, community-acquired pneumonia, and STIs.