Clonidine

(clonidine hydrochloride, immediate release)

Clonidine (clonidine hydrochloride, immediate release); not controlled

Summary

Clonidine immediate-release tablets are a central alpha-2 adrenergic agonist approved for hypertension only, in adults; safety and effectiveness in pediatric patients have not been established. It is short acting and given in divided daily doses. It is not the ADHD product: only extended-release clonidine carries the ADHD indication, and any ADHD use of this tablet is off label, most often a bedtime dose for sleep onset. Not controlled; generic only.

Forms & Strengths

• Tablets, immediate release: 0.05 mg, 0.1 mg, 0.2 mg, 0.3 mg
• Separate labels, not covered here and not interchangeable:
  • Clonidine ER tablets 0.1 mg (Kapvay generics): ADHD indicated
  • Onyda XR, ER oral suspension 0.1 mg/mL: ADHD indicated
  • Nexiclon XR 0.17 mg: hypertension
  • Clonidine transdermal system: 0.1, 0.2, 0.3 mg/24 h; hypertension
  • Javadin oral solution 0.02 mg/mL: adult hypertension
  • Clonidine injection (Duraclon): epidural analgesia

Dosing

• Age: adults; pediatric safety and effectiveness not established
• Onset: blood pressure falls in 30 to 60 min, maximum at 2 to 4 hours; ADHD benefit is not an effect of this product
• Duration: dosed twice daily; half-life 12 to 16 hours
• Initial Dose: 0.1 mg twice daily, morning and bedtime; lower in elderly or renal impairment
• Titration: 0.1 mg/day every 7 days to response
• Max Dose: usual range 0.2 to 0.6 mg/day divided; label maximum effective dose 2.4 mg/day
• Considerations: This is the hypertension product, not the ADHD product; give the larger share of the daily dose at bedtime to limit dry mouth and drowsiness, and never substitute it milligram-for-milligram for an extended-release clonidine.

Off-label pediatric ADHD dosing: [VERIFY] No FDA-approved pediatric ADHD dosing exists for immediate-release clonidine. Weight-band values published previously are withheld pending a graded pediatric source. For labeled pediatric ADHD dosing use extended-release clonidine or Onyda XR.

Pharmacology

• Mechanism: Central alpha-2 adrenergic agonist; reduces sympathetic outflow from the locus coeruleus and enhances prefrontal noradrenergic signalling. Not a CNS stimulant; mechanism in ADHD unknown.
• Delivery / Release: Immediate-release tablet; bioavailability 70% to 80%, peak plasma 1 to 3 hours.
• Metabolism: About 50% hepatic, 40% to 60% renal unchanged. Half-life 12 to 16 hours, up to 41 in severe renal impairment; haemodialysis removes minimal drug.
• Class Positioning: Non-selective alpha-2 agonist, more sedating than guanfacine, which is alpha-2A selective. Against Kapvay and Onyda XR the difference is kinetic, not pharmacodynamic: same moiety, different release, different indication, no mg-for-mg equivalence.

Indications

• Hypertension (ICD-10: I10): adults, alone or with other antihypertensives. The only approved indication on this label.
• ADHD is not an approved indication for this product. Extended-release clonidine (Kapvay) and Onyda XR are the ADHD-approved clonidine products, ages 6 to 17.

Off-Label Uses

• ADHD (ICD-10: F90.0-F90.9): the studied agents are ER guanfacine and ER clonidine, effect size about 0.7 versus 1.0 for stimulants; the IR tablet is expert consensus at best. (AAP 2019)
• Tic disorders and Tourette syndrome (ICD-10: F95.1, F95.2): class option, most useful with comorbid ADHD. Supported by controlled trials for the class; limited data for IR clonidine. (AACAP 2013)
• Sleep-onset insomnia in ADHD (ICD-10: G47.00): commonest real-world use. Limited data; sedation is a labeled adverse effect, not a demonstrated benefit.
• Where the evidence does not support use: oppositional defiant disorder and aggression (ICD-10: F91.3); insufficient for IR clonidine.

Contraindications & Warnings

• Contraindicated: known hypersensitivity to clonidine
• Warning, withdrawal: abrupt cessation causes a rapid rise in blood pressure; rare hypertensive encephalopathy, stroke and death reported
• Use with caution:
  • Sinus node dysfunction or AV block; severe bradycardia needing atropine and pacing reported
  • Concurrent sympatholytics, especially digitalis, calcium channel blockers, beta-blockers
  • Renal impairment; half-life up to 41 hours, so start lower and monitor
  • Any child prone to vomiting illness; missed doses are de facto abrupt discontinuation
  • Contact lens wearers, because of dry eyes
  • Pheochromocytoma; no therapeutic effect expected
• Screen before starting:
  • Blood pressure and heart rate, supine and standing
  • History of syncope, bradycardia, heart block or conduction disease
  • Renal function
  • Sympatholytic and sedating co-medication, including any beta-blocker

Drug Interactions

• Beta-blockers: additive bradycardia and worse withdrawal hypertension; if both stop, withdraw the beta-blocker several days first
• AV nodal agents (digitalis, calcium channel blockers): monitor heart rate; bradycardia needing pacing reported with diltiazem and verapamil
• Sedatives and alcohol (barbiturates, benzodiazepines, antihistamines): potentiated CNS depression; ask at every visit
• Tricyclic antidepressants: reduce the hypotensive effect; recheck blood pressure when either is started or stopped
• Neuroleptics: worsen orthostatic hypotension; check orthostatic vitals after adding either agent
• Other antihypertensives: additive lowering; adjust and recheck

Administration

• Same times daily, with or without food; food does not affect kinetics
• Give the larger share of the daily dose at bedtime
• The 0.1, 0.2 and 0.3 mg tablets are scored and may be bisected
• The 0.05 mg tablet is listed by a single labeler; confirm stock with the pharmacy
• Do not substitute mg-for-mg for Kapvay, Onyda XR or the transdermal system
• Do not stop abruptly; see Discontinuation & Taper
• Continue to within 4 hours of surgery, resume promptly, monitor blood pressure perioperatively
• Store locked; as little as 0.1 mg has produced toxicity in a small child

Side Effects

• Common (adult label rates, dose related, diminish over time): dry mouth 40%, drowsiness 33%, dizziness 16%, constipation 10%, sedation 10%
• Serious:
  • Withdrawal with rebound hypertension, rarely hypertensive encephalopathy, stroke, death; never stop abruptly
  • Bradycardia, sinus arrest, high-degree AV block; stop and obtain an ECG for syncope or slow, irregular pulse
  • Orthostatic hypotension and syncope; recheck standing vitals, reduce or hold
  • Hallucinations, delirium, depression; discontinue and reassess
  • Raynaud phenomenon, hepatitis, thrombocytopenia, colonic pseudo-obstruction
  • Angioedema, urticaria, generalised rash, especially after prior transdermal sensitisation

Monitoring & Labs

• Heart rate and blood pressure: baseline, after each increase, then every 3 months
• Orthostatics: lying and standing at baseline, at every dose change, and at any dizziness visit
• Sedation: ask at every titration visit and every visit for 3 months; commonest reason for stopping
• Rebound risk: at every refill confirm no missed doses and restate that the drug is never stopped abruptly
• ECG: not routine; baseline if conduction disease, syncope history or concurrent sympatholytics, and promptly for new syncope or bradycardia
• Renal function: baseline, annually, and after any illness that could impair it
• Mood and perception: ask about depression and hallucinations each visit; neither is volunteered
• Laboratory: no other routine monitoring required

Discontinuation & Taper

• Never stop abruptly. Reduce the dose gradually over 2 to 4 days
• Abrupt cessation: nervousness, agitation, headache, tremor, then rapid blood pressure rise; rarely hypertensive encephalopathy, stroke, death
• Risk rises with higher doses and continued beta-blockade; withdraw the beta-blocker several days first, then taper clonidine
• An excessive post-discontinuation rise reverses with oral clonidine or IV phentolamine
• A vomiting illness in a child is de facto abrupt discontinuation; families should call rather than let doses lapse
• Drug holidays are not appropriate for this class

Pregnancy & Lactation

• Pregnancy: no adequate controlled human studies; clonidine crosses the placenta. Rats showed increased resorptions, rabbits no teratogenicity. Use only if clearly needed; ER labels note decades of human use without an identified defect risk.
• Lactation: milk levels about double maternal serum; relative infant dose 4.1% to 8.4%. One infant had drowsiness, hypotonia, suspected seizures and apnoea. Monitor for sedation, lethargy, tachypnoea, poor feeding. (LactMed 2024)
• Lactation, milk supply: dose-related oxytocin and prolactin effects; postpartum galactorrhea and hyperprolactinaemia with gynecomastia reported. Other antihypertensives preferred while nursing a newborn. (LactMed 2024)

Counseling Points

• Counsel the family on:

  • Why this tablet is not the ADHD-approved product, and why the box says hypertension
  • Never stopping on their own, even for a few days; name rebound high blood pressure as the reason
  • Calling if the child cannot keep the medicine down, because missed doses and withdrawal are the same thing
  • Dry mouth and drowsiness peaking early, dose related, easing with time
  • Standing up slowly, and calling rather than pushing through dizziness
  • Keeping the bottle locked; one 0.1 mg tablet can seriously harm a small child
  • Avoiding alcohol and sedating medicines, including over-the-counter antihistamines

• Advise them to call for:

  • Fainting, or dizziness on standing that does not settle in a minute or two
  • A pulse that feels very slow or irregular
  • Drowsiness so heavy the child is hard to wake
  • Severe headache with blurred vision or confusion, especially after missed doses
  • Seeing or hearing things that are not there, or a marked mood change
  • Numbness or colour change in the fingers or toes
  • Any vomiting illness that stops the medicine going down

References

1. DailyMed. Clonidine hydrochloride tablets, USP prescribing information. Actavis Pharma, Inc. 2022. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=a842ab83-3531-44dd-a8a8-64dd89e87026
2. DailyMed. Clonidine hydrochloride extended-release tablets prescribing information. Actavis Pharma, Inc. 2023. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=0100c70d-7fde-46a1-8374-940550a27e43
3. DailyMed. Catapres-TTS (clonidine transdermal system) prescribing information. Boehringer Ingelheim. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=39e1d35e-533c-4647-8649-8168a6e92dfa
4. LactMed. Clonidine. Drugs and Lactation Database, National Institute of Child Health and Human Development. 2024. https://www.ncbi.nlm.nih.gov/books/NBK501628/
5. American Academy of Pediatrics. Clinical practice guideline for the diagnosis, evaluation, and treatment of attention-deficit/hyperactivity disorder in children and adolescents. Pediatrics. 2019. https://publications.aap.org/pediatrics/article/144/4/e20192528/81590/
6. AACAP. Practice parameter for the assessment and treatment of children and adolescents with tic disorders. Journal of the American Academy of Child and Adolescent Psychiatry. 2013. https://www.jaacap.org/article/S0890-8567(13)00695-3/fulltext
7. FDA. openFDA National Drug Code Directory, clonidine, queried by generic name across all labelers. 2026. https://api.fda.gov/drug/ndc.json?search=generic_name:%22clonidine%22&limit=1000