Guanfacine: Nursing Drug Guide, Hypotension & NCLEX Review
Central alpha-2A agonist therapy for ADHD or hypertension can drop blood pressure and heart rate—especially after dose increases, dehydration, or missed extended-release doses—and abrupt stops cause rebound hypertension. On shift, pair orthostatic blood pressure measurement, fall precautions, verified ER swallow-whole administration, and a written taper plan before the patient stands or drives.
Guanfacine labeling warns of hypotension, bradycardia, and syncope during therapy and rebound hypertension after abrupt discontinuation or missed extended-release doses. The highest-stakes nursing failures are giving ER tablets crushed or chewed, stopping without a ≤1 mg every 3–7 day taper, missing orthostatic vitals after dose changes, and stacking with other blood-pressure-lowering drugs without review. Measure vital signs before titration steps, hold and escalate for symptomatic hypotension or presyncope, and never substitute IR Tenex mg-for-mg for ER Intuniv.
📋 Contents
⚡ Quick facts
💡 Key takeaway
Before every dose change, check blood pressure and heart rate sitting and standing, confirm ER tablets are swallowed whole, and verify a taper plan if therapy stops. Missed ER doses or abrupt discontinuation can trigger rebound hypertension—coordinate with pharmacy rather than restarting the full dose without prescriber review.
Most common brand names
Guanfacine is available as immediate-release (IR) and extended-release (ER) oral products. Verify whether the order specifies IR or ER—products are not interchangeable mg-for-mg per prescribing information.
Intuniv (guanfacine extended-release) is labeled for ADHD in children and adolescents 6–17 years. Tenex (guanfacine immediate-release) is labeled for hypertension in adults. Generic guanfacine tablets exist in both formulations; always match formulation, strength, and schedule on the MAR.
Why we give it — Indications
Guanfacine is a selective central alpha-2A adrenergic agonist. Nurses most often administer extended-release guanfacine as non-stimulant ADHD therapy and immediate-release guanfacine for hypertension—each formulation has distinct dosing, food, and discontinuation rules.
| Use | Detail |
|---|---|
| ADHD (ER — Intuniv) | Monotherapy or adjunctive therapy for ADHD in children and adolescents 6–17 years when stimulants are insufficient or not tolerated per ER labeling |
| Hypertension (IR — Tenex) | Management of hypertension; may be used alone or with other antihypertensive agents per IR labeling |
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How it works
Guanfacine stimulates central alpha-2A adrenergic receptors, reducing sympathetic outflow. In ADHD, this mechanism is thought to strengthen prefrontal cortex regulation of attention and impulse control. In hypertension, reduced peripheral sympathetic tone lowers blood pressure. Because effects include sedation, bradycardia, and hypotension, nursing care must prioritize hemodynamic monitoring and safe discontinuation—not only behavioral symptom control.
Dosing overview
Always verify formulation (IR vs ER), indication, weight-based targets for ADHD, and CYP3A4 interacting drugs before administration.
Extended-release (ADHD)
Immediate-release (hypertension — Tenex)
CYP3A4 adjustments (ER labeling)
| Interaction | Example | Dose adjustment |
|---|---|---|
| Strong CYP3A4 inhibitor | Ketoconazole | Reduce guanfacine to 50% of target dose |
| Strong CYP3A4 inducer | Carbamazepine | May need up to double the target dose—titrate carefully with vitals |
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Missed ER dose: If a dose is missed, take the next dose at the usual time—do not double. Contact pharmacy/prescriber if multiple consecutive doses are missed because rebound hypertension risk increases.
Onset, peak, duration, and half-life
| Parameter | Value | Nursing relevance |
|---|---|---|
| ER peak plasma | Approximately 5 hours postdose under fasting conditions per ER labeling | Reassess sedation and blood pressure after peak; high-fat meals increase exposure |
| ER half-life | Approximately 18 hours (17.2 h in adults; 14.4 h in children 6–12 y per labeling) | Once-daily dosing; missed doses and abrupt stop carry rebound risk |
| IR half-life | Not specified in the reviewed prescribing information | Bedtime IR dosing aligns with peak hypotensive effect overnight—teach slow morning rising |
| Food effect (ER) | High-fat meal increases Cmax about 44% and AUC about 37% | Avoid high-fat meals with ER; consistent timing supports predictable vitals |
| Metabolism | Primarily CYP3A4 | Review inhibitors/inducers during medication reconciliation |
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Before you give it — Safety check
Pretreatment checks
- Confirm IR vs ER product, dose, and time; verify tablets are intact if ER
- Review blood pressure, heart rate, and recent orthostatic symptoms (dizziness, fainting)
- Screen for concurrent antihypertensives (amlodipine, propranolol) and sedating drugs that worsen hypotension or sedation
- Assess hydration—dehydration can worsen hypotension
- Check CYP3A4 inhibitors/inducers on MAR; confirm dose was adjusted if ketoconazole or carbamazepine started or stopped
Contraindications
- Hypersensitivity to guanfacine or product components per labeling
Warnings and cautions
- Hypotension, bradycardia, and syncope—measure vitals before dose increases and after missed doses
- Sedation and somnolence—avoid hazardous tasks until response is known; monitor for excessive sleepiness
- Rebound hypertension after abrupt discontinuation or missed ER doses—requires taper
- Cardiac conduction abnormalities—use caution with history of syncope, bradycardia, or heart block; consider ECG context when ordered
Important interactions
| Drug / factor | Effect | Nursing action |
|---|---|---|
| Other antihypertensives / beta-blockers | Additive hypotension and bradycardia | Obtain orthostatic vitals; hold if symptomatic hypotension |
| CYP3A4 inhibitors | Increased guanfacine exposure | Verify 50% dose reduction per ER labeling when strong inhibitor added |
| CYP3A4 inducers | Decreased guanfacine exposure | Anticipate need for higher dose with careful titration and monitoring |
| CNS depressants | Increased sedation | Assess alertness; fall precautions; avoid driving until stable |
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Administration
Extended-release (Intuniv): Swallow tablets whole with water. Do not crush, chew, or break ER tablets. May take once daily in the morning or evening at about the same time. Avoid high-fat meals because they increase drug exposure per labeling.
Immediate-release (Tenex): Take at bedtime to align with peak hypotensive effect. Not interchangeable mg-for-mg with ER products.
- Independent double-check formulation and strength—IR vs ER errors are high risk
- If patient cannot swallow whole ER tablet, notify prescriber/pharmacy—do not crush at bedside
- Document time, dose, and any pre-dose vitals when institutional policy requires
Expected therapeutic response
- ADHD: improved attention, impulse control, and hyperactivity over weeks of titration—not immediate like stimulants
- Hypertension: lower blood pressure readings over days to weeks with bedtime IR dosing
- Stable heart rate and blood pressure without presyncope after dose changes
- Mild sedation may occur early—should not progress to unarousable somnolence
Red flags — Stop and act
- Syncope, presyncope, or sustained dizziness with standing—hold dose and obtain orthostatic vitals
- Systolic blood pressure or heart rate below ordered parameters after dose increase or missed-dose restart
- Rebound hypertension (headache, flushing, BP above baseline) after abrupt stop or multiple missed ER doses
- Bradycardia with lethargy or poor perfusion—escalate per protocol
- Severe sedation, unarousable patient, or respiratory depression when combined with CNS depressants
Adverse effects
| Adverse effect | Context | Nursing response |
|---|---|---|
| Hypotension, bradycardia, syncope | Warnings in labeling; more likely with dose increases and drug interactions | Orthostatic vitals, fall precautions, hold and notify prescriber/pharmacist |
| Sedation, somnolence, fatigue | Common in ADHD trials | Assess alertness; avoid sedative stacking; teach hazard avoidance |
| Headache, abdominal pain | Reported in clinical trials | Supportive care; differentiate from rebound hypertension on discontinuation |
| Vomiting, nausea, constipation | GI complaints reported | Monitor hydration and intake; escalate if persistent with hypotension |
| Dry mouth, appetite decrease | Common mild effects | Oral care; monitor weight in pediatric ADHD patients |
| Rebound hypertension | After abrupt ER discontinuation or missed doses | Do not restart full dose without prescriber plan; implement taper |
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Overdose, toxicity, and antidote
Overdosage of guanfacine may produce hypotension, drowsiness, lethargy, and bradycardia per labeling. Initial hypertension may precede hypotension. There is no specific antidote; management is supportive.
- Monitor blood pressure, heart rate, and level of consciousness continuously
- Supportive care including IV fluids for hypotension per prescriber and protocol
- Contact local poison control or medical toxicology services per facility protocol and local emergency guidance
Look-alike / sound-alike and error prevention
- Guanfacine vs clonidine—both alpha-2 agonists; verify drug name and taper requirements on every pass
- Intuniv ER vs Tenex IR—not interchangeable mg-for-mg; formulation errors cause hypotension or rebound hypertension
- Guanfacine vs guanabenz—similar names; confirm generic and brand on label
- Crush/split ER—never crush extended-release guanfacine; pharmacy must provide alternative if swallowing is impossible
- Duplicate alpha-2 therapy—guanfacine plus clonidine or methyldopa increases hypotension risk
Practical bedside notes
| Topic | Bedside guidance |
|---|---|
| ER swallow | Whole tablet only—if patient spits partial tablet, do not re-administer without pharmacy guidance |
| High-fat meals | Avoid with ER doses; cafeteria fried foods can increase exposure unexpectedly |
| Missed doses | Two or more missed ER doses—notify prescriber before next home dose; rebound hypertension risk |
| School/daycare | Confirm who gives AM vs PM dose; consistent timing supports stable vitals |
| Commonly missed | Restarting full ER dose after gaps; crushing ER for enteral feeds; ignoring CYP3A4 interaction dose changes |
| Ask pharmacy when | Strong inhibitor/inducer added, enteral tube administration needed, or unclear taper after hold |
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High-risk populations
| Population | Considerations |
|---|---|
| Dehydration / acute illness | Hypotension and syncope risk increase—monitor intake and output and orthostatic vitals |
| Chronic kidney disease | Not specified in the reviewed prescribing information for dose adjustment—coordinate with pharmacy if renal function declines |
| Cirrhosis / hepatic impairment | CYP3A4 metabolism may be altered—monitor vitals closely when interacting drugs or dose changes occur |
| Cardiac history | Bradycardia, syncope, or conduction disease—enhanced monitoring; hold for symptomatic bradycardia |
| Pediatric ADHD patients | Weight-based titration; caregiver teaching on ER swallow and missed-dose rebound risk |
| Pregnancy | ER labeling: no identified drug-associated risk with available data; pregnancy exposure registry exists per labeling |
| Lactation | No human milk data for ER; monitor infant for sedation, lethargy, poor feeding; LactMed prefers other agents with more data for newborn/preterm infants when alternatives exist |
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Monitoring and documentation
Monitor
- Blood pressure and heart rate (sitting and standing) before and after dose increases per labeling
- Signs of syncope, sedation, and behavioral response in ADHD
- Blood pressure trend if rebound hypertension suspected after missed doses or discontinuation
- Heart rate and rhythm if bradycardia or conduction concerns—coordinate with prescriber orders for cardiac monitoring when clinically indicated
Document
- Formulation (IR vs ER), dose, time, and whether tablet was swallowed whole
- Pre-dose vitals when required by policy or after prior hypotensive episode
- Missed doses, taper instructions, and prescriber/pharmacy notifications
- Patient/caregiver teaching on orthostatic safety and hazard avoidance
Patient teaching
- “This medicine can lower blood pressure and slow your heart rate—stand up slowly and sit down if you feel dizzy.”
- Swallow extended-release tablets whole; do not crush, chew, or break them
- Take at the same time each day; if you miss doses, call your prescriber before restarting—do not double up
- Do not stop suddenly; taper per prescriber instructions to avoid rebound high blood pressure
- Avoid driving or hazardous tasks until you know how guanfacine affects alertness
- Breastfeeding parents: watch the infant for unusual sleepiness or poor feeding and report concerns promptly
The Hold Rule
- Known hypersensitivity to guanfacine
- Symptomatic hypotension, presyncope, syncope, or heart rate below ordered limits
- ER tablet damaged, crushed, or patient unable to swallow whole—clarify alternative with pharmacy
- Order to stop ER therapy without a taper plan (≤1 mg every 3–7 days per labeling)
- Multiple missed ER doses—clarify restart dose with prescriber/pharmacist before giving full maintenance dose
- New strong CYP3A4 inhibitor or inducer without verified dose adjustment
Hold parameters may vary by institutional protocol. Follow prescriber orders, pharmacy guidance, and facility policy.
Clinical practice integration and workflow
Guanfacine errors cluster around IR/ER mix-ups, crushed ER tablets, missed-dose restart without prescriber review, and underestimating hypotension when combined with other antihypertensives.
1. Check-before-you-give protocol
- Right patient, right formulation (IR vs ER), right dose, right time
- Tablet intact for ER; patient can swallow whole
- Orthostatic vitals when policy requires or after prior hypotensive episode
- CYP3A4 interaction check complete on MAR
2. High-alert and safety badge
Hemodynamic-risk alpha-2 agonist — orthostatic vitals and taper on discontinuation3. Clinical workflow: hold and question rules
- If ER tablet is crushed in MAR instructions, hold and clarify with pharmacy—never crush at bedside
- If patient fainted after dose increase, hold next dose and obtain orthostatic vitals before prescriber callback
- If discharge omits taper for ER therapy, question pharmacy before final MAR print
4. Critical teach-back questions
- “What should you do if you miss two doses?” (Call prescriber/pharmacy before restarting—do not double dose.)
- “Why must you stand up slowly?” (Medicine can drop blood pressure and cause dizziness or fainting.)
🧠 Quick mental checklist
- Is this IR Tenex or ER Intuniv—and does the dose match the formulation?
- Did I check sitting and standing blood pressure and heart rate when required?
- Will the patient swallow the ER tablet whole without crushing?
- Are any CYP3A4 inhibitors or inducers on the MAR with adjusted guanfacine dose?
- If stopping or multiple doses were missed, is there a taper or restart plan from prescriber/pharmacy?
Guanfacine NCLEX practice questions
Practice NCLEX-style clinical judgment practice for guanfacine hypotension and taper safety using a tabbed pediatric ADHD case (MAR, labs, vitals, nursing notes) with missed extended-release doses and rebound hypertension, then priority action, cue recognition (SATA), vital-sign trend interpretation, matrix urgency sorting, clinical judgment, and documentation cloze—recognise cues → analyse → prioritise → act → evaluate outcomes.
Select a tab to view MAR, labs, vitals, and nursing note details for this case.
- Guanfacine ER 3 mg PO once daily — missed Friday and Saturday (weekend away); Sunday dose given 0800
- Methylphenidate ER 36 mg PO once daily — held this morning per parent request (stomach ache)
- No ketoconazole or carbamazepine on MAR
- Discharge instruction draft says “stop guanfacine if ineffective”—not yet signed
- Basic metabolic panel today: sodium 138 mEq/L; potassium 4.0 mEq/L; creatinine 0.6 mg/dL (baseline)
- No hepatic panel ordered
- Prior visit BP percentile documented; no new labs ordered for hypertension workup
- Baseline (on stable 3 mg ER): BP 102/64 mmHg, HR 78/min
- Today 0900 (after missed doses + restart): BP 128/86 mmHg, HR 92/min, RR 18, SpO2 99% RA
- Today 0930 standing: reports mild dizziness; BP 118/82 mmHg, HR 88/min
- Weight 42 kg; alert but tired
- Parent gave “the full 3 mg tablet” Sunday AM after two missed days—did not call clinic first
- Patient reports headache and feeling “revved up”; denies chest pain
- School nurse note: child usually tolerates ER tablet whole with water; no high-fat breakfast today
- RN planning orthostatic vitals and prescriber notification about missed-dose restart and rising BP
Answer key & rationale
Frequently asked questions
Why is orthostatic hypotension a major guanfacine safety concern?
Labeling warns of hypotension, bradycardia, and syncope. Measure blood pressure and heart rate before dose increases and when patients report dizziness or fainting. Use fall precautions and teach slow position changes.
What happens if guanfacine ER is stopped abruptly?
Rebound hypertension can occur. Taper by no more than 1 mg every 3 to 7 days when discontinuing per ER labeling. Clarify taper plans before holding or stopping therapy.
Can guanfacine ER tablets be crushed or split?
No. ER tablets must be swallowed whole and must not be crushed, chewed, or broken per prescribing information.
How do CYP3A4 inhibitors and inducers change guanfacine dosing?
Strong inhibitors such as ketoconazole may require reducing the dose to 50% of target. Strong inducers such as carbamazepine may require up to double the target dose with careful monitoring.
Is guanfacine safe during pregnancy and breastfeeding?
ER labeling reports no identified drug-associated risk with available pregnancy data. No human milk data exist; monitor breastfed infants for sedation or poor feeding. LactMed prefers other agents with more data for newborn or preterm infants when alternatives exist.
References
- U.S. National Library of Medicine. Guanfacine extended-release tablets — Full prescribing information. DailyMed.https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=6006df06-0448-462d-b81e-7add50a6d71b
- U.S. National Library of Medicine. Tenex (guanfacine) tablets — Full prescribing information. DailyMed.https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=886e050c-dd22-4f35-ac3b-243f091125c3
- Drugs and Lactation Database (LactMed). Guanfacine. Bethesda (MD): National Institute of Child Health and Human Development.https://www.ncbi.nlm.nih.gov/books/NBK501522/
Review and transparency
This medication guide is written and reviewed using NurseOnShift editorial and clinical review standards.
Educational use only. This content does not replace clinical judgment, prescriber orders, pharmacist guidance, product labeling, or institutional protocols.