Tremor, clinical pharmacology

1. Tremor
Domina Petric, MD

2. Tremor
Tremor consists of rhythmic oscillatory movements.
Physiologic postural tremor, which is a normal
phenomenon, is enhanced in amplitude by anxiety,
fatigue, thyrotoxicosis and intravenous epinephrine
or isoproterenol.
Propranolol reduces the amplitude of postural tremor.
If the propranolol is administered intra-arterially, it
prevents the response to isoproterenol in the
perfused limb.

3. Tremor
Bronchodilators, valproate, tricyclic antidepressants and
lithium may produce a dose-dependent exaggeration of
the normal physiologic tremor that is reversed by
discontinuing the drug.
The tremor produced by sympathomimetics (for example,
bronhcodilator terbutaline) is blocked by propranolol,
but not by metoprolol.
Propranolol antagonizes both β1 and β2 receptors.
Metoprolol is β1-selective antagonists.
Such tremor is mediated mainly by the β2 receptors.

4. Essential tremor
Essential tremor is postural tremor, sometimes familial with
autosomal dominant inheritance.
Gene loci: ETM1 on 3q13, ETM2 on 2p24.1, locus on 6p23.
Dysfunction of β1 receptors: essential tremor responds to
standard doses of both metoprolol and propranolol.
Propranolol is used in dose of 40-120 mg orally twice daily.
Propranolol should be used with caution in patients with heart
failure, heart block, asthma and hypoglycemia.
Metoprolol can be useful in patients with concomitant
pulmonary disease that contraindicates use of propranolol.

5. Essential tremor
Primidone can be also used for essential tremor in
gradually increasing doses up to 250 mg three
times daily.
Patients with tremor are very sensitive to
primidone.
Start dose: 50 mg once daily.
Daily dose is increased by 50 mg every 2 weeks
depending on response.

6. Essential tremor
Topiramate: 400 mg daily, built up gradually.
Alprazolam: up to 3 mg daily.
Gabapentin: 100-2400 mg/day.
Im. injection of botulinom toxin.
Thalamic stimulation.
Small quantities of alcohol: not recommended.

7. Intention tremor
It is present during movement, but not at rest.
Sometimes occurs as a toxic manifestation of alcohol or
drugs such as phenytoin.
Withdrawal or reduction in dosage provides dramatic
relief.
There is no satisfactory pharmacologic treatment for
intention tremor due to other neurologic disorders.
Rest tremor is usually due to parkinsonism.

8. Literature
Katzung, Masters, Trevor.
Basic and clinical
pharmacology.