Drug General Information (ID: DDIZALO13H)
  Drug Name Minoxidil Drug Info Guanfacine Drug Info
  Drug Type Small molecule Small molecule
  Therapeutic Class Antihypertensive Agents Antiadrenergic Agents
  Structure

 Mechanism of Minoxidil-Guanfacine Interaction (Severity Level: Moderate)
     Additive hypotensive effects Click to Show/Hide Mechanism Graph
Could Not Find 2D Structure
      Drug Name Minoxidil Guanfacine
      Mechanism Antihypertensive agent
ATP-sensitive inward rectifier potassium channel  Inducer
Antihypertensive agent
Alpha-2 adrenergic receptor  Agonist
      Key Mechanism Factor 1
Factor Name Inward rectifier potassium channel Structure Sequence
Protein Family Inward rectifier-type potassium channel (TC 1.A.2.1) family
Protein Function
This receptor is controlled by G proteins. Inward rectifier potassium channels are characterized by a greater tendency to allow potassium to flow into the cell rather than out of it. Their voltage dependence is regulated by the concentration of extracellular potassium; as external potassium is raised, the voltage range of the channel opening shifts to more positive voltages. The inward rectification is mainly due to the blockage of outward current by internal magnesium. Can be blocked by extracellular barium (By similarity). Subunit of ATP-sensitive potassium channels (KATP). Can form cardiac and smooth muscle-type KATP channels with ABCC9. KCNJ11 forms the channel pore while ABCC9 is required for activation and regulation.
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      Key Mechanism Factor 2
Factor Name Adrenergic receptor alpha-2 Structure Sequence
Protein Family G-protein coupled receptor 1 family
Protein Function
Alpha-2 adrenergic receptors mediate the catecholamine-induced inhibition of adenylate cyclase through the action of G proteins. The rank order of potency for agonists of this receptor is oxymetazoline > clonidine > epinephrine > norepinephrine > phenylephrine > dopamine > p-synephrine > p-tyramine > serotonin = p-octopamine. For antagonists, the rank order is yohimbine > phentolamine = mianserine > chlorpromazine = spiperone = prazosin > propanolol > alprenolol = pindolol.
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      Mechanism Description
  • Additive hypotensive effects by the combination of Minoxidil and Guanfacine 

Recommended Action
      Management Caution is advised during coadministration of these agents. Dosage adjustments may be required and hemodynamic responses should be monitored during concomitant therapy. Patients should be advised to avoid rising abruptly from a sitting or recumbent position and to notify their doctor if they experience dizziness, lightheadedness, syncope, orthostasis, or tachycardia. Patients should also avoid driving or operating hazardous machinery until they know how the medications affect them.

References
1 Cerner Multum, Inc. "Australian Product Information.".
2 Cerner Multum, Inc. "UK Summary of Product Characteristics.".
3 Product Information. Tenex (guanfacine). Wyeth-Ayerst Laboratories, Philadelphia, PA.