Drug General Information (ID: DDIVETDW52)
Drug Name			Protriptyline		Drug Info		Lofexidine		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Antidepressants				Antihypertensive Agents
Structure

Mechanism of Protriptyline-Lofexidine Interaction (Severity Level: Moderate)
Additive CNS depression effects Click to Show/Hide Mechanism Graph
Drug Name		Protriptyline				Lofexidine
Mechanism 1		CNS depression effects				CNS depression effects
Key Mechanism Factor 1
		Factor Name		CNS depression effects
		Factor Description		CNS depressants are drugs that inhibit or suppress brain activity and can reduce mental and physical processes. Excessive CNS depression can lead to decreased heart rate, slow breathing (less than 10 breaths per minute), extreme confusion or loss of memory, nausea and vomiting, poor judgment, blue lips or fingertips, irritability and aggression, and clammy or cold skin.
Mechanism Description		Additive CNS depression effects by the combination of Protriptyline and Lofexidine
Increased risk of prolong QT interval Click to Show/Hide Mechanism Graph
Drug Name		Protriptyline				Lofexidine
Mechanism 2		Prolong QT interval				Prolong QT interval
Key Mechanism Factor 2
		Factor Name		QT interval
		Factor Description		Long QT syndrome is a heart signaling disorder that can cause a fast, chaotic heartbeat (arrhythmia). Many people may not exhibit symptoms, and usually the condition is detected during routine medical tests. In others, the most common symptoms include: sudden fainting, palpitations, dizziness, seizures, sudden death.
Mechanism Description		Increased risk of prolong QT interval by the combination of Protriptyline and Lofexidine

Recommended Action
Management		During concomitant use of these drugs, patients should be monitored for altered efficacy and excessive or prolonged CNS depression. Patients should be made aware of the possibility of additive effects (e.g., drowsiness, dizziness, lightheadedness, confusion) and be cautioned about driving, operating machinery, or performing other hazardous tasks. The manufacturer recommends that the concurrent use of lofexidine with other medications that can prolong the QT interval be avoided. If no alternatives are available, patients should be advised to seek medical attention if they experience symptoms that could indicate the occurrence of torsades de pointes such as dizziness, palpitations, or syncope.

References
1	Cerner Multum, Inc. "UK Summary of Product Characteristics.".
2	Product Information. Lucemyra (lofexidine). US WorldMeds LLC, Louisville , KY.