Phentermine Discontinuation Prior to Surgery

Rationale for Discontinuation

• Phentermine is a sympathomimetic medication that can cause significant perioperative complications due to its effects on the cardiovascular system 1
• As a norepinephrine reuptake inhibitor, phentermine can lead to both hyperadrenergic effects and paradoxical refractory hypotension during surgery 2

Timing of Discontinuation

• The American Gastroenterological Association (AGA) clinical practice guideline specifically recommends discontinuing phentermine and phentermine-containing medications at least 4 days before procedures requiring anesthesia 1, 2

Mechanism of Perioperative Risk

• Phentermine's sympathomimetic properties can cause hyperadrenergic effects that become hazardous during anesthesia 2
• Paradoxically, phentermine can also lead to refractory hypotension during surgery, possibly due to catecholamine depletion and autonomic dysfunction 2

Comparison with Other Medications

• Unlike some other medications that may be continued until the day of surgery, phentermine requires this specific washout period due to its sympathomimetic effects 3
• Other medications with sympathomimetic properties, such as ergotamine, also require discontinuation (at least 2 days prior to surgery) 3, 4