Question

define diuretics and explain their main uses. what are the four main categories of fiuretics ?

Explain the action of each type of diuretic categories.

What are the common antidysrhythmic drugs and what is the action of each on the heart.

Answer 1

Definition : Diuretics also known as water pills are drugs which cause a net loss of sodium ion and water in urine.

Diuretics increases the excretion of water from the body.

Categories of diuretics:

• loop diuretics
• thiazide
• potassium sparing
• carbonic anhydrase inhibitors

Loop Diuretic: Inhibit the luminal Na/K/2Cl co-transporter) in the thick ascending limb in the loop of Henle.

Thiazide Diuretics: Inhibit reabsorption of sodium an dchloride ions from the distal convoluted by blocking sensitive sodium and sodium ions symportter. stimulate the reabsorption of calcium.

Potassium sparind diuretic: Competitively binds the aldostererone receptor preventing the hormone from binding to its receptors. aldosterone's normal steriod-nuclear DNA Transcription is halted.

Carbonic anhydrase inhibitors: Inhibits the carbonic anhydrase enzyme found in covulated tubule resulting in several effects including bicarbonate retention in the urine, potassium retention in urine and decreased sodium absorption.

Common antidysrythmic drugs are:

• Amiodarone: It is a long acting drug. it prolong APD by blocking potassium ion channels , blocks inactivated sodium channels, blocks calcium ions channels, decrease conduction and decrease ectopic automacity.
• quinidine: Binds to open and inactivated sodium channels and prevent sodium influx resulting in slowing down the rapid upstroke during phase 0. decreases slop of phase 4 spontaneous depolarization and inhibit potassium channels
• Sotalol: prolong the action potential in bi=oth atria and ventricles.
• amlodopine: blocks voltage sensitive L- type Ca channels by binding to specific site on the a-1 subunit preventing the entry of Ca into the cell resulting in no excitation-coupling reaction in heart and vascular smooth muscles.