Do patients taking Tenex (guanfacine) for Attention Deficit Hyperactivity Disorder (ADHD) or hypertension require a taper to discontinue the medication?

Tapering Tenex (Guanfacine) Upon Discontinuation

Yes, Tenex (guanfacine) should be tapered when discontinuing, not stopped abruptly, due to the risk of rebound hypertension and withdrawal symptoms.

Why Tapering is Necessary

The FDA drug label explicitly warns that patients should be advised not to discontinue guanfacine therapy abruptly, as abrupt cessation of orally active central α2-adrenergic agonists may be associated with increases in plasma and urinary catecholamines, symptoms of nervousness and anxiety, and less commonly, increases in blood pressure to levels significantly greater than those prior to therapy. 1

• Guanfacine is a centrally acting α2A-adrenergic agonist that suppresses sympathetic nervous system activity during treatment 1, 2
• When stopped suddenly, there is a physiologic rebound as the body readjusts to the absence of central sympathetic suppression 1
• The American Academy of Pediatrics specifically recommends that extended-release guanfacine should always be tapered rather than suddenly discontinued due to risk of rebound hypertension 3

Evidence on Withdrawal Effects

While guanfacine has a more favorable withdrawal profile compared to clonidine, withdrawal phenomena still occur:

• Research shows that abrupt withdrawal leads to gradual recovery of blood pressure over 2-4 days, with plasma noradrenaline returning to and eventually exceeding pretreatment levels by day 4 4
• Four out of five patients in one study reported headaches starting from the second day after withdrawal 4
• The withdrawal syndrome with guanfacine is generally milder than with clonidine, and symptoms are typically less severe, but this does not eliminate the need for tapering 2

Recommended Tapering Approach

Reduce the dose gradually over 2-4 days to one week:

• For patients on higher doses (3-4 mg/day), decrease by 1 mg every 3-4 days 5
• For patients on lower doses (1-2 mg/day), decrease by 0.5-1 mg every 3-4 days 5
• The taper schedule used in clinical trials involved reducing from 4 mg to 3 mg to 2 mg to 1 mg over 4-day intervals, which proved safe and well-tolerated 5

Monitoring During Discontinuation

Monitor blood pressure and heart rate closely during and after the taper:

• Check vital signs at each dose reduction and for at least one week after complete discontinuation 1
• Watch for symptoms of withdrawal including headache, nervousness, anxiety, and elevated blood pressure 1, 4
• The American Academy of Child and Adolescent Psychiatry recommends developing a monitoring plan after stopping medications like guanfacine to assess for return of ADHD symptoms, as symptom recurrence may take weeks to months to emerge 3

Special Considerations

For patients taking guanfacine with enzyme inducers (phenobarbital, phenytoin), more careful tapering may be necessary:

• These medications reduce guanfacine's elimination half-life and plasma concentration, potentially making withdrawal effects more pronounced 1
• If guanfacine is discontinued in patients on enzyme inducers, careful tapering of the dosage is necessary to avoid rebound phenomena 1

The context matters for discontinuation planning:

• When discontinuing multiple medications in patients with ADHD and comorbid conditions, consider which medication to discontinue first based on which disorder is more likely to be in remission or less severe 3
• Ensure adequate follow-up monitoring is arranged, especially in inpatient or partial hospital settings with short lengths of stay where unexpected symptom return after discharge could be missed 3