The main antiparkinsonians mentioned are L-DOPA, Selegiline, and ropinarole. These only delay progression of the disease somewhat briefly.
L-DOPA
This increases dopamine by increasing the production. This happens because L-dopa is the immediate precursor of dopamine and higher amounts in the system will lead to more dopamine production.
This has large systemic side effects, as a relatively small part of it reaches the brain. This is reduces by coprescribing with carbidopa which is a L-DOPA decarboxylase inhibitor which does not pass the blood brain barrier. This will in turn lead to less conversion in the body but not the brain.
The problem with L-DOPA is that
Side effects
- acute effects may include naesea and vomiting (maybe adjust dose if you see this)
- Dyskinesia
- Psychiatric disturbances
- Vivid dreams
- hallucinations
- psychotic states
- confusion
- impulse control disorders
Selegiline
This is a MonoOxidaseAmineInhibitor. This stops the breakdown of dopamine in the cleft, increaseing the signalling provided by each release. It can offer some antidepressant effects, and increases levels of noradrenaline too.
This can be used with L-DOPA, and can be given with early stages of the disease
Side effects of selegiline
- twitching twisting and uncontrolled reptitive movements
- Insomnia
- Loss of appetite
- Severe interactions with reuptake inhibitors
Ropinirole
This is a dopamine (D2,D3,D4) agonist, as the D2 family (containing these receptors) is inhibitory, these will inhibit the indirect pathway (no-go pathway)
Side effects
- hallucinations
- nausea and vomiting
- disruption of natural pleasure reward pathways
- increased risk of gambling and impulse control disorders