CHAPTER 7 Urinary Drugs

Quiz Yourself 1. Thiazide diuretic drugs act at the loop of Henle and the distal renal tubule to increase the excretion of sodium. They block sodium and potassium from being reabsorbed from the tubule back into the blood. More sodium and potassium than usual are excreted in the urine and therefore more water as well. This decreases the blood pressure. Loop diuretic drugs act at the proximal convoluted tubule, the loop of Henle, and the distal convoluted tubule. They block sodium and potassium from being reabsorbed from the tubule back into the blood. More sodium and potassium than usual are excreted in the urine and therefore more water as well. This decreases the blood pressure. Potassium-sparing diuretic drugs act at the proximal convoluted tubule and the loop of Henle. They cause sodium and water to be excreted in the urine, but they spare (or conserve) potassium and allow it to be reabsorbed from the tubule back into the blood. This decreases the blood pressure. Osmotic diuretic drugs in the filtrate within Bowman’s capsule increase the concentration (osmolarity) of the filtrate. As the filtrate moves through the tubules, its higher osmolarity continues to hold water and electrolytes to it and prevents water from being reabsorbed from the tubules back into the blood. This decreases the blood pressure. Carbonic anhydrase inhibitor diuretic drugs inhibit the enzyme carbonic anhydrase in the tubule wall cells. This means that bicarbonate and hydrogen ions are not formed. When no positive hydrogen ions are available to exchange places with positive sodium ions, the sodium ions stay in the filtrate and hold water with them, and thus produce greater volumes of urine (diuresis). This decreases the blood pressure.

2. Many potassium supplements contain the letter K in their trade name because K+ is the chemical symbol for potassium.

3. Patients on a diuretic drug often need to take a potassium supplement because diuretic drugs cause sodium and potassium to be excreted. The excessive loss of potassium can cause serious side effects. Patients are prescribed a potassium supplement to prevent this.

4. Gram-negative bacteria, specifically E. coli from the GI tract, are the most common cause of UTIs.

5. Sulfonamide drugs inhibit the growth of bacteria but do not kill them, as antibiotic drugs do. 6. Urinary analgesic drugs are prescribed to treat the symptoms of burning and painful urination associated with UTIs.

7. [Only need to give two.] Pyridium turns the urine bright orange. Dolsed, Trac Tabs 2X, Urised, and Urogesic Blue turn the urine a blue-green color. 8. Finasteride (Proscar) is used to treat benign prostatic hypertrophy (BPH).

9. Alpha1-receptor blocker drugs for BPH block alpha1 receptors in the smooth muscle of the urethra and prostate. This causes the smooth muscle to relax and allows urine to flow more easily in patients who have an enlarged prostate gland.

10. PDE5 inhibitor drugs, such as sildenafil (Viagra), tadalafil (Cialis), and vardenafil (Levitra), are given orally to inhibit the enzyme PDE5 that inactivates cGMP. This allows more active cGMP to relax the smooth muscles of the arteries in the penis, increase blood flow, and create an erection. Prostaglandin E1 drugs, such as alprostadil (Caverject, Edex, Muse), relax the smooth muscle in the arteries of the penis, increase blood flow, and create an erection; these drugs are given locally as an injection (Caverject, Edex) or inserted into the urethra as a pellet (Muse).

11. a. Androgen inhibitor drug for BPH b. Loop diuretic drug c. Potassium supplement d. Thiazide diuretic drug e. Urinary analgesic drug f. PDE5 inhibitor drug for erectile dysfunction g. Alpha1-receptor blocker drug for benign prostatic hypertrophy h. Drug for overactive bladder i. PDE5 inhibitor drug for erectile dysfunction

Clinical Applications Questions 1. a. hydrochlorothiazide b. generic name c. Aldactone d. trade name e. diuretic drugs f. Hydrochlorothiazide is a thiazide diuretic drug that blocks sodium and potassium from being reabsorbed from the tubule back into the blood. Aldactone is a potassium-sparing diuretic drug that spares (or conserves) potassium and allows it to be reabsorbed from the tubule back into the blood. g. Aldactone, because it conserves potassium and keeps it from being excreted in the urine. 2. a. hydrochlorothiazide b. 50 mg c. tablets d. Dispense 30 tablets. Write on the label: Take one. Four refills.