Other names: Beta-receptor blockers, beta-receptor blockers, β-blockers, beta-adrenoceptor antagonists
1. Function of beta blockers¶
Beta-blockers inhibit the activating effect of adrenaline and noradrenaline on the β-adrenoceptors. This reduces the stimulating effect of the sympathetic nervous system on the target organs, primarily the heart. Beta-blockers counteract the effects of adrenaline on other organ systems.
β1-adrenoceptors stimulate:
- Cardiac output (cardiac output and heart rate)
- Blood pressure
- Kidney: increased release of the blood pressure-increasing enzyme renin, which has a blood pressure-lowering effect.
β2-adrenoceptors act on the smooth muscles of
- Bronchi
- Uterus
- Blood vessels.
Blockade has a contracting effect on the smooth muscles, which, among other things, increases the tone of the bronchial muscles, which can lead to them spasming. Therefore, bronchial asthma (unlike COPD) is a contraindication for β2-acting beta blockers.
2. Effect of various beta blockers¶
Beta-blockers have different β-adrenoceptor affinities.
| Active ingredient |
β1-blocker |
β2-blocker |
Other effects |
| Acebutolol |
x |
|
ISA |
| Alprenolol |
x |
x |
ISA |
| Atenolol |
x |
|
|
| Betaxolol |
x |
|
|
| Bisoprolol |
x |
|
|
| Bupranolol |
x |
x |
|
| Butoxamine |
|
x |
|
| Carteolol |
x |
x |
Stimulation of NO release in endothelial cells, ISA |
| Carvedilol |
x |
x |
Blockade of α1 receptors |
| Celiprolol |
x |
|
ISA |
| Esmolol |
x |
|
very short-acting |
| ICI-118,551 |
|
x |
|
| Labetalol |
x |
x |
Blockade of α1 receptors |
| Landiolol |
x |
|
very short-acting |
| Metipranolol |
x |
x |
|
| Metoprolol |
x |
|
|
| Nadolol |
x |
x |
|
| Nebivolol |
x |
|
Stimulation of NO release in endothelial cells |
| Oxprenolol |
x |
x |
ISA |
| Penbutolol |
x |
x |
|
| Pindolol |
x |
x |
ISA |
| Practolol |
x |
|
ISA |
| Propranolol |
x |
x |
|
| Sotalol |
x |
x |
Class III antiarrhythmic drug |
| Talinolol |
x |
|
|
| Timolol |
x |
x |
|
|
|
|
|
|
|
|
|
ISA: intrinsic sympathomimetic activity, also partial agonistic activity (PAA). IdR undesirable.
Acebutolol and pindolol should be avoided due to reduced cardiac efficacy and increased arterial vascular resistance.
CI-118,551 and butoxamine are currently used for research purposes only.
3. Beta blockers for ADHD¶
Beta blockers are not a common medication for ADHD.
However, a small study reports helpful comedication together with stimulants.
Another small study reported a responder rate of 85% for propanolol monotherapy.
An open-label study of propranolol in ADHD adults with anger outbursts is said to report improvements at daily doses of up to 640 mg ((Wilens and
Spencer, 1999, cited in Biederman J, Spencer T, Wilens (2004):. Evidence-based pharmacotherapy for attention-deficit hyperactivity disorder. Int J Neuropsychopharmacol. 2004 Mar;7(1):77-97. doi: 10.1017/S1461145703003973. PMID: 14733627.))
A double-blind, placebo-controlled study compared 2 x 20 mg pindolol and 2 x 10 mg MPH daily in 52 children with ADHD. Pindolol showed so much more frequent paresthesia and more intense nightmares and hallucinations than MPH or placebo that the trial was terminated after 32 participants. Pindolol improved hyperactivity and behavioral problems at home and hyperactivity at school as effectively as MPH. However, pindolol was inferior to MPH on psychological tests and in terms of behavioral problems at school. Overall, pindolol was moderately effective for ADHD, with significant risks of side effects. Pindolol should be avoided anyway due to reduced cardiac efficacy and increase in arterial vascular resistance.
A study of nadolol in 12 children with aggression and developmental delay found clinical improvements in 10 children, but these were not significant in terms of inattention/hyperactivity.
A Swedish cohort study found no association between beta-blockers and ADHD.
In our opinion, beta blockers could be a useful adjunct to ADHD treatment in cases of comorbid aggression or comorbid cardiac problems.
It should be noted that many beta-blockers and amphetamine drugs are metabolized via CYP2D6. Therefore, taking them together can reduce the effect. However, this should not be a problem as long as this effect is taken into account.
