Renal Pharmacology

Question 1

osmotic diuretics MOA

Answer 1

The proximal tubule and descending limb of Henle’s loop are freely permeable to water.
An osmotic agent that is not reabsorbed causes water to be retained in these segments and promotes a water diuresis.
They also oppose the action of ADH in the collecting tubule.

Question 2

The prototypic osmotic diuretic is ?

Answer 2

mannitol

Question 3

pk of osmotic diuretics

Answer 3

Osmotic diuretics are poorly absorbed, which means that they must be given parenterally.
If administered orally, mannitol causes osmotic diarrhea. Mannitol is not metabolized and is excreted primarily by glomerular filtration within 30–60 minutes,

Question 4

Indication for osmotic diuretics / therapeutic use

Answer 4

treatment for patients with increased intracranial pressure or acute renal failure due to shock, drug toxicities, and trauma

Question 5

ADRs of osmotic diuretics

Answer 5

Extracellular Volume Expansion
Dehydration and Hypernatremia

Question 6

Vasopressin (Antidiuretic Hormone, ADH)

Answer 6

Vasopressin is a peptide hormone released by the posterior pituitary in response to rising plasma tonicity or falling blood pressure.

Question 7

deficiency of ADH results in

Answer 7

diabetes insipidus

Question 8

PK of ADH

Answer 8

Vasopressin is administered by intravenous, intramuscular, or intranasal routes; oral absorption is slight.
The half-life of circulating ADH is approximately 20 minutes, with renal and hepatic metabolism.
A small amount of vasopressin is excreted as such in the urine.

Question 9

MOA of ADH

Answer 9

Vasopressin interacts with two types of receptors.
V1 receptors are found on vascular smooth muscle cells and mediate vasoconstriction
V2 receptors are found on renal tubule cells and mediate antidiuresis through increased water permeability and water resorption in the collecting tubules.

Question 10

The long-acting synthetic analog of vasopressin is?

Answer 10

Desmopressin acetate (DDAVP) with minimal V1 activity and an antidiuretic-to-pressor ratio 4000 times that of vasopressin.

Question 11

Clinical Pharmacology / Therapeutic use

Answer 11

Vasopressin and desmopressin are the alternative treatments of choice for pituitary diabetes insipidus.
Bedtime desmopressin therapy treats nocturnal enuresis by decreasing nocturnal urine production.
Vasopressin infusion is effective in some cases of esophageal variceal bleeding and colonic diverticular bleeding.

Question 12

Toxicity & Contraindications of ADH

Answer 12

Headache, nausea, abdominal cramps, agitation, and allergic reactions occur rarely. Therapy can result in hyponatremic convulsions.
Vasopressin (but not desmopressin) can cause vasoconstriction and should be used cautiously in patients with coronary artery disease.
Nasal inhalation of desmopressin may be less effective when nasal congestion is present