#1_1 Drug Absorption — Answer the questions below.
1. Primary site of drug and nutrient absorption?
Answer & Explanation
Most drugs are absorbed in the small intestine (large surface area, rich blood flow); the ileum is a major site.2. Which factor most increases passive diffusion across gut epithelium?
Answer & Explanation
Non-polar, unionized drugs diffuse best through lipid membranes.3. First-pass metabolism mainly occurs in the…
Answer & Explanation
Drugs absorbed from GI tract reach the liver via the portal vein and may be extensively metabolized before systemic entry.4. Which route bypasses first-pass metabolism?
Answer & Explanation
Sublingual absorption drains to systemic veins → avoids hepatic first-pass.5. Gastric emptying that is faster will generally…
Answer & Explanation
Faster emptying delivers drug to the main absorptive surface sooner → quicker onset (often ↑Cmax).6. Pancreatic bicarbonate secretion into the duodenum mainly…
Answer & Explanation
Neutralization improves solubility/dissolution; bile is still needed for lipids/lipophilic drugs.7. Which statement about the esophagus is correct?
Answer & Explanation
The esophagus transports contents to the stomach and contributes little to absorption.8. Food with high fat content most likely…
Answer & Explanation
Fatty meals stimulate bile → micelles → better uptake of lipophilic drugs (but effect is drug-specific).9. Weak acids are better absorbed in the stomach than weak bases because…
Answer & Explanation
Unionized form diffuses better. Note: most absorption still occurs in small intestine.10. Which factor decreases oral bioavailability?
Answer & Explanation
Enterocyte P-gp pumps drug back to lumen → lowers net absorption.11. Difference between the ileum and the intestine?
Answer & Explanation
“Ileum” is one segment of the small intestine; “intestine” refers to the whole intestinal tract.
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#1_2 Drug Distribution — Answer the questions below.
1) Which statement best defines Volume of Distribution (Vd)?
Answer & Explanation
B. Vd is an apparent volume: Vd = (amount in body) / (plasma concentration). It is a conceptual parameter, not a real anatomical space.2) A highly lipophilic drug with minimal plasma protein binding will most likely have:
Answer & Explanation
C. Lipophilic drugs partition into tissues/fat and, with low binding, leave little in plasma → large apparent Vd.3) Which factor most decreases distribution of a BASIC drug?
Answer & Explanation
A. Basic drugs bind α1-acid glycoprotein; higher levels increase binding → lower free fraction → reduced distribution.4) Perfusion-limited distribution is best described as:
Answer & Explanation
B. If the drug crosses membranes readily, distribution speed is determined by perfusion.5) Which structure most restricts entry of polar, non-transported drugs into the CNS?
Answer & Explanation
B. BBB tight junctions and transporters (e.g., P-gp) limit CNS penetration of polar drugs.6) A 70-kg patient receives 500 mg IV bolus; initial plasma concentration C₀ = 10 mg/L. What is Vd?
Answer & Explanation
D. Vd = Dose/C₀ = 500 mg ÷ 10 mg·L⁻¹ = 50 L, indicating extensive tissue distribution.7) Which situation increases the free concentration of a highly albumin-bound ACIDIC drug?
Answer & Explanation
A. Displacement from albumin raises the unbound fraction → ↑ pharmacologic effect and clearance; monitor toxicity.8) The rapid loss of effect after a single IV dose of thiopental occurs primarily because:
Answer & Explanation
B. Highly lipophilic thiopental redistributes rapidly from well-perfused brain to peripheral tissues, terminating anesthesia.9) In pregnancy, which is most accurate regarding placental transfer?
Answer & Explanation
B. Weak bases become protonated in relatively more acidic fetal circulation → ionized → trapped.10) Which clinical state most increases Vd for HYDROPHILIC drugs (e.g., aminoglycosides)?
Answer & Explanation
B. Expanded extracellular water increases the distribution space for hydrophilic drugs → larger Vd and higher loading doses.
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#1_3 Liver Metabolism — Answer the questions below.
1) Which vessel delivers nutrient-rich blood from the GI tract for first-pass metabolism?
Answer & Explanation
B. The portal vein carries blood from the gut to the liver, exposing drugs to first-pass metabolism.2) Phase I reactions are classically catalyzed by which system and where?
Answer & Explanation
A. Phase I (oxidation/reduction/hydrolysis) is mainly mediated by CYPs on the smooth ER.3) Which of the following is a Phase II conjugation?
Answer & Explanation
B. Glucuronidation conjugates glucuronic acid to drugs, markedly increasing polarity.4) Which statement about first-pass effect is CORRECT?
Answer & Explanation
B. Oral/upper-rectal absorption drains to portal circulation → hepatic metabolism before systemic entry lowers F.5) An active metabolite formed by CYP2D6 from codeine is:
Answer & Explanation
B. Codeine is O-demethylated by CYP2D6 to morphine, a more potent μ-agonist (pharmacogenetically variable).6) Which situation most likely decreases hepatic clearance of high-extraction drugs (e.g., propranolol)?
Answer & Explanation
A. High-extraction drugs are flow-limited; less hepatic perfusion → lower clearance.7) Which pair correctly matches inhibitor → affected CYP?
Answer & Explanation
B. Grapefruit components inhibit intestinal CYP3A4 → ↑oral bioavailability of CYP3A substrates.8) Which statement about the ligaments labeled on the liver is TRUE?
Answer & Explanation
C. Ligamentum teres is the obliterated umbilical vein; falciform ligament attaches liver to anterior abdominal wall; coronary ligament to diaphragm.9) Which patient factor typically reduces hepatic metabolic capacity?
Answer & Explanation
A. Loss of functional hepatocyte mass and blood flow reduces intrinsic clearance.10) Which route best avoids first-pass metabolism for a drug requiring rapid systemic effect?
Answer & Explanation
B. Oral mucosal absorption drains to systemic veins, providing rapid effect while bypassing first-pass metabolism.
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#1_4 Kidney Excretion — Answer the questions below.
1) Which structure is the primary site of drug filtration in the kidney?
#1_5 Routes of Administration
1. Which route of administration completely avoids the first-pass metabolism?
Explanation: Sublingual administration bypasses the portal circulation and thus avoids first-pass metabolism.
2. Which route delivers the fastest onset of drug action?
Explanation: Intravenous administration provides immediate systemic circulation access, fastest onset.
3. Which route is specifically designed for sustained release?
Explanation: Transdermal patches provide a slow, steady release of drug.
4. Which route involves drug delivery directly into cerebrospinal fluid?
Explanation: Intrathecal administration places drug into cerebrospinal fluid for direct CNS action.
5. Which route of administration is often used for local dermatological conditions?
Explanation: Topical administration delivers drug directly to skin or mucosa for local effect.
6. Which administration route is MOST suitable for unconscious patients?
Explanation: Intravenous is preferred for unconscious patients because oral/sublingual routes are unsafe.
7. Which route is partly subject to first-pass effect?
Explanation: Rectal administration undergoes ~50% first-pass metabolism depending on venous drainage.
8. Which route allows for highly targeted and rapid respiratory drug delivery?
Explanation: Inhalation delivers drug rapidly to lungs for local or systemic effect.
9. Which route is most commonly used for vaccines?
Explanation: Vaccines are usually given intramuscularly (e.g., deltoid muscle).
10. Which route provides a balance between ease of administration and steady absorption?
Explanation: Subcutaneous injections provide relatively steady absorption, easy to administer.
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Answer & Explanation
B. The glomerulus filters free (unbound) drug into Bowman’s capsule.2) Which factor most limits glomerular filtration of a drug?
Answer & Explanation
A. Only free drug passes glomerular pores; bound drug is retained in plasma.3) Where does active tubular secretion of weak acids (e.g., penicillin) primarily occur?
Answer & Explanation
B. Organic anion/cation transporters in proximal tubule secrete drugs into lumen.4) Weak bases are most likely to be trapped and excreted when urine is:
Answer & Explanation
C. In acidic urine, weak bases are protonated → ionized → poorly reabsorbed → excreted.5) Which clearance value indicates renal drug excretion is primarily via secretion?
Answer & Explanation
A. If clearance exceeds GFR, tubular secretion is contributing.6) In renal failure, which PK parameter is most directly affected?
Answer & Explanation
B. Decreased renal function directly lowers clearance of renally excreted drugs.7) Which drug property favors renal tubular reabsorption?
Answer & Explanation
B. Non-ionized lipophilic molecules diffuse back into blood.8) Which renal parameter is used clinically to estimate GFR?
Answer & Explanation
B. Creatinine clearance is a standard clinical surrogate of GFR.9) For a weak acid drug overdose, which intervention enhances excretion?
Answer & Explanation
B. Alkaline urine ionizes weak acids → trapped in lumen → excreted.10) Which is TRUE about renal drug excretion?
Answer & Explanation
C. Polar, ionized molecules can’t diffuse back → efficiently eliminated in urine.11. Which of the following is a key feature of vaginal drug administration?
Answer & Explanation
B. Vaginal administration allows both local treatment and systemic absorption while avoiding significant first-pass metabolism.12. How does vaginal drug administration relate to first-pass metabolism?
Answer & Explanation
B. Vaginal drug delivery avoids the hepatic first-pass effect, leading to higher systemic bioavailability compared to oral administration.13. What is a specific advantage of vaginal administration of hormonal drugs (e.g., estrogen, progesterone)?
Answer & Explanation
B. Vaginal delivery avoids extensive first-pass hepatic metabolism, resulting in more predictable systemic levels of hormones such as estrogen and progesterone.
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