Dopamine receptor agonists
1, The preferred monotherapy option for early, younger PD patients.
2, One of the combination drug therapy options in case of diminished efficacy of compounded dopa or the development of motor complications.
3.One of the advantages of the commonly used dopamine agonists is their long half-life, and the stimulation of dopamine receptors is better than the “pulse-like stimulation” of compound dopa, but close to the physiological state of continuous dopaminergic stimulation (CDS).
4. About 50% of PD patients can achieve satisfactory results with dopamine agonist monotherapy within 3 years.
5. More than 30% of PD patients maintain dopamine agonist monotherapy for more than 5 years.
The main non-ergot derivatives in common use today are
1.Ropinirole: It is a DR2 agonist and has an effect on DR3, but not on DR1. Half-life 6h. effective dose 6mg/d.
2, Pramipexole: DR2 agonist, also has effect on DR3 and DR4. Half-life 8~12h. Mean dose 1.5~4.5mg/d.
3.Tysocta extended release tablet (Trastal SR): It has agonistic effect on DR2 and DR3, and also has effect on DR1. Clinical treatment improves PD: 31% for increased muscle tone, 41% for tremor, and 48% for dyskinesia. Combination with levodopa increases the efficacy, reduces the number of doses, delays complications and increases tolerability. The dose is 150-250mg/d.
Characteristics of dopamine agonists
1.Advantages
Directly agonize dopamine receptors
Not dependent on dopaminergic peripheral nerve function
Reduce the risk of allodynia
Not influenced by protein in food
Delayed motor complications
2. Limitations
Dose needs to be titrated to increase Dosage
Initial side effects include nausea and vertigo
Mental side effects (hallucinations and delusions) are increased
Daytime sleepiness
Lower limb edema
Rare cases of obsessive-compulsive disorder
Dopamine agonist usage.
DR agonists should be started in small doses and gradually increased to appropriate doses that control symptoms without side effects such as postural hypotension, psychiatric symptoms, edema, erythema. The risk of daytime sleepiness needs to be noted. Early titration of small doses of the drug may avoid common adverse effects such as headache and nausea.