Clonidine is available in immediate release and sustained release.
Trade names of clonidine are:
- Catapresan (A, D, CH)
- Haemiton (D)
- Isoglaucon (A, D)
- Paracefan (D)
- Kapvay (USA; prolonged-release clonidine hydrochloride):
Clonidine is a rather atypical medication for ADHD.
The stated Effect size of 0.71 for children and adolescents seems too high and is due to an insufficient number of studies. Another meta-analysis found an Effect size of 0.03.
Clonidine is commonly used in autism spectrum disorders and may be helpful in comorbid ASD + ADHD in young children.
1. Mechanisms of action of clonidine¶
Clonidine is an alpha-2-adrenoceptor agonist.
-
Agonist of the σ-2A adrenoreceptor
-
Agonist of the σ-2B adrenoreceptor
-
Agonist of the σ-2C adrenoreceptor
Clonidine is also an imidazoline receptor agonist.
If the dosage is too high and too fast (injected), clonidine can also act as a σ-1-adrenoceptor agonist.
Clonidine weakens the effect of adrenaline.
Alpha-2 adrenoceptors are activated by the neurotransmitters adrenaline and noradrenaline. They are therefore responsible for the effects mediated by adrenaline and noradrenaline.
Alpha-2-A receptor agonists such as clonidine and guanfacine are thought to enhance a phasic release of noradrenaline in the nucleus coeruleus, which improves attention as well as working memory and visuomotor-associated learning (as opposed to a long-term tonic release of noradrenaline, which impairs performance).
Clonidine thus has a noradrenergic effect.
As an alpha-2-adrenoceptor agonist, clonidine (like guanfacine) significantly reduces the release of dopamine in the nucleus accumbens in the laboratory.
Clonidine and guanfacine are said to be helpful for rejection sensitivity in ADHD, according to a report by an American ADHD specialist.
A 2019 study from India reported that clonidine was the most commonly used medication for ADHD in a group of children aged 3 to 6 years with ADHD:
- Clonidine: 44, 6 %
- Risperidone: 28.7 %
- Methylphenidate: 10.7 %
- Atomoxetine: 10.7 %
Clonidine worked better than methylphenidate with halperidol in children with ADHD and comorbid tic disorders.
2. Side effects¶
Side effects of clonidine have not yet been incorporated.
Clonidine has higher side effects than methylphenidate and atomoxetine.
Older people may have more frequent endothelial damage (damage to the inner layer of blood vessels). In these people, clonidine could increase the risk of vascular damage and thrombosis.
