Published: 7 September 2023
Publications
Spotlight on clonidine
Published: 7 September 2023
Prescriber Update 44(3): 46–48
September 2023
Adverse drug reactions have been reported in people using clonidine
for off-label indications. This article is a reminder of the approved
indications, noting that clonidine is not recommended for use in children.
See the
data
sheets for full prescribing information.
Mechanism of action
Clonidine stimulates alpha-2 adrenoreceptors in the brain stem.1,2 This results in reduced sympathetic outflow from the central nervous system and decreases in peripheral resistance, renal vascular resistance, heart rate and blood pressure.1–3
Indications and formulations
Clonidine containing medicines have several indications and formulations. Table 1 summarises the clonidine products that are approved and available in New Zealand.
Clonidine is not recommended for use in children1-5
Clonidine is not recommended for use in children due to the limited supporting efficacy and safety information from randomised control trials. Serious adverse reactions, including death, respiratory depression (slow, shallow breathing), bradycardia (low heart rate) and hypotension (low blood pressure), have been reported in children when clonidine has been used concomitantly with methylphenidate for an off-label purpose.
Table 1: Summary of clonidine products approved and available by product name, formulation and indication, as at 28 June 2023
| Product | Formulation and strength | Indication |
|---|---|---|
| Catapres | Oral tablet 150mcg | Oral: treatment of hypertension (alone or concomitantly with other antihypertensive agents) |
| Solution for injection 150mcg/mL | Parenteral: treatment of hypertensive crises | |
| Catapres-TTS | Transdermal patch 2.5mg/3.5cm2, 5mg/7.0cm2, 7.5mg/10.5cm2 | Treatment of mild to moderate hypertension (alone or concomitantly with other antihypertensive agents) |
| Clonidine (Teva) | Oral tablet 25mcg | Prophylactic management of migraine or recurrent vascular
headaches Management of vasomotor conditions commonly associated with menopause and characterised by flushing |
| Clonidine HCl injection | Solution for injection 150mcg/mL | Treatment of hypertensive crises |
| Clonidine Transdermal System USP | Transdermal patch 0.1mg/day, 0.2mg/day, 0.3mg/day | Treatment of mild to moderate hypertension (alone or concomitantly with other antihypertensive agents) |
Sources:
Catapres, Catapres-TTS, Clonidine (Teva), Clonidine HCl Injection and Clonidine Transdermal System USP data sheets, available at: medsafe.govt.nz/Medicines/infoSearch.asp (accessed 17 July 2023).
Other considerations for use1–5
Clonidine can impair driving
Advise patients that they may experience dizziness, sedation and accommodation disorder (eg, blurry vision) during treatment with clonidine. Patients should not drive or operate machinery if they experience these effects.
Sudden discontinuation
Restlessness, palpitations, rapid rise in blood pressure, nervousness, tremor, headaches or nausea have been reported with sudden discontinuation of clonidine. Advise patients to speak to their healthcare provider before discontinuing treatment. Prescribers should gradually reduce the patient’s dose over 2–4 days when discontinuing clonidine.
Adverse effects and overdose
The most frequently reported adverse effects include dry mouth, sedation, dizziness and orthostatic hypotension (dizziness when standing after sitting or lying down).4,5 Transdermal application is also associated with skin reactions, including contact dermatitis (itchy rash), pruritis (itchy skin) and erythema (redness).1,2
There are an increasing number of international reports of clonidine overdose in children. These reports relate to accidental poisoning and dosing errors, many of which required medical intervention and/or hospitalisation.6,7
New Zealand data
Up to January 2023, the Centre for Adverse Reactions Monitoring (CARM) had received 127 suspected adverse reaction reports for clonidine, of which 11 were reported in children.
Of the 127 reports to CARM, the most frequently reported reaction terms were rash, dermatitis contact, depression, peripheral ischemia (impaired blood supply to the limbs) and nausea. Reports in children related to application site rash, somnolence (sleepiness), bradycardia and akathisia (a movement disorder that makes it hard to stay still).
From 1 January 2018 to 31 December 2022, the National Poisons Centre received 115 calls relating to clonidine exposure. Of these, 56 calls were related to exposure in a child aged 12 years or younger and in 21 of these calls, the child was exposed to clonidine by unintended exploratory access.
When prescribing or dispensing clonidine, remind patients about correct storage and disposal to ensure it remains out of sight and reach of children.
References
- CARSL Consulting. 2019. Catapres-TTS New Zealand Data Sheet 1 February 2019. URL: medsafe.govt.nz/profs/Datasheet/c/CatapresTTS.pdf (accessed 22 June 2023).
- Viatris New Zealand. 2022. Clonidine Transdermal System USP New Zealand Data Sheet 15 March 2022. URL: www.medsafe.govt.nz/profs/Datasheet/c/ClonidineTransdermalSystemUSP.pdf (accessed 23 June 2023).
- Clinect NZ Pty Limited. 2020. Catapres Data Sheet 30 October 2020. URL: www.medsafe.govt.nz/profs/datasheet/c/Cataprestabinj.pdf (accessed 23 June 2023).
- Teva Pharma New Zealand Limited. 2021. Clonidine (Teva) New Zealand Data Sheet 12 October 2021. URL: www.medsafe.govt.nz/profs/Datasheet/c/clonidinebnmtab.pdf (accessed 22 June 2023).
- Medicianz Healthcare Limited. 2022. Clonidine HCl Injection New Zealand Data Sheet 20 January 2022. URL: www.medsafe.govt.nz/profs/Datasheet/c/clonidinehydrochlorideinj.pdf (accessed 28 June 2023).
- Cairns R, Brown JA and Buckley NA. 2019. Clonidine exposures in children under 6 (2004–2017): a retrospective study. Archives of Disease in Childhood 104(3): 287–91. DOI: 10.1136/archdischild-2018-316026 (accessed 25 June 2023).
- Osterhoudt K. 2023. Clonidine, xylazine, and related imidazole poisoning In: UpToDate 16 June 2023. URL: www.uptodate.com/contents/clonidine-and-related-imidazoline-poisoning (accessed 20 June 2023).
