Author Question: A calcium channel blocker has been prescribed for a client with hypertension. The nurse explains ... (Read 49 times)

xclash · **on:** Jul 23, 2018

A calcium channel blocker has been prescribed for a client with hypertension. The nurse explains that this drug affects the function of the L-type calcium channel by which action?

1. Enhancing the action potential along the cell membrane
2. Changing the shape of the L-type calcium channel
3. Blocking sympathetic input to the cell membrane
4. Competing for calcium receptors on the L-type calcium channel

Question 2

The nurse is assessing a client taking both verapamil and digoxin. Which finding indicates an adverse interaction of this drug combination?

1. Pulse rate 51 beats per minute
2. Respiratory rate 42 breaths per minute
3. Blood pressure 184/96 mmHg
4. Serum potassium 5.6 mEq/L

covalentbond · **Reply #1 on:** Jul 23, 2018

Answer to Question 1

Correct Answer: 2
Rationale 1: Opening of the calcium channel and entry of calcium into myocytes and vascular smooth muscle cells occur in response to the action potential, but calcium channel blockers do not exert their therapeutic effects by interfering with the action potential.
Rationale 2: By altering the shape of the calcium channel, calcium channel blockers prevent entry of calcium into cells.
Rationale 3: The L-type calcium channel opens in response to sympathetic stimulation, but calcium channel blockers do not inhibit this input.
Rationale 4: The role of the calcium channel is to control entry of calcium into cells. The calcium channel blockers prevent entry of calcium through the channel without competing for receptors with calcium ions.
Global Rationale: By altering the shape of the calcium channel, calcium channel blockers prevent entry of calcium into cells. Opening of the calcium channel and entry of calcium into myocytes and vascular smooth muscle cells occur in response to the action potential, but calcium channel blockers do not exert their therapeutic effects by interfering with the action potential. The L-type calcium channel opens in response to sympathetic stimulation, but calcium channel blockers do not inhibit this input. The role of the calcium channel is to control entry of calcium into cells. The calcium channel blockers prevent entry of calcium through the channel without competing for receptors with calcium ions.

Answer to Question 2

Correct Answer: 1
Rationale 1: Risk of bradycardia is greater with this drug combination, since both drugs slow conduction through the AV node.
Rationale 2: The drugs are not associated with an increase in respiratory rate.
Rationale 3: Hypertension is not associated with either drug.
Rationale 4: Hyperkalemia does not occur as a result of the interaction of these drugs, although if serum potassium is abnormally high for another reason, potassium ions might compete for digoxin receptors and decrease the therapeutic effect of digoxin.
Global Rationale: Risk of bradycardia is greater with this drug combination, since both drugs slow conduction through the AV node. The drugs are not associated with an increase in respiratory rate. Hypertension is not associated with either drug. Hyperkalemia does not occur as a result of the interaction of these drugs, although if serum potassium is abnormally high for another reason, potassium ions might compete for digoxin receptors and decrease the therapeutic effect of digoxin.