Levodopa
General
Levodopa is an anti-Parkinsonian drug used to treat Parkinson's disease. The aim of this therapy is to increase the concentration of dopamine in the basal cells in the cerebrum.
Levodopa is a so-called prodrug and, in contrast to the activated active ingredient dopamine, it can cross the blood-brain barrier so that it works where one would like to therapeutically achieve an increased dopamine concentration.
Levodopa is always given in combination with a decarboxylase inhibitor (e.g. carbidopa, benserazide) in order to be able to reduce the peripheral side effects (e.g. nausea and vomiting).
If a patient is treated with levodopa for a longer period of time, movement disorders can occur, which in turn can be treated therapeutically with drugs (dopamine antagonists).
Mode of action
Levodopa is used to compensate for the lack of dopamine in the brain, which is caused by the loss of function and destruction of dopaminergic nerve cells in the black matter of the brain when Parkinson's disease is present.
The Parkinson's symptoms such as slow movement and stiffness can be treated well through the use of levodopa. The symptoms of tremors, speech disorders, swallowing disorders and the rigid gait, on the other hand, cannot be treated with levodopa, so that only partial improvement can be achieved with the drug.
The effect of levodopa is based on the fact that the dopamine interacts with the postsynaptic dopaminergic receptors D1 and D2.
application areas
Levodopa should not be used in Parkinson's disease caused by medication.
Good application however, in the treatment of the "Normal" Parkinson's disease and the so-called "Restless Leg Syndrome".
Contraindications
Not applied may be levodopa an allergy (Hypersensitivity), at Angle-closure glaucoma (Disruption of the drainage of the excess tear fluid and thus increased pressure in the eye), in which Presence of melanoma, simultaneous use of non-selective MAOIs or the Use of metoclopramide.
Interactions
Becomes at the same time as taking the drug Levodopa a high protein meal, Antacids, Dopamine antagonists (Neuroleptics) or iron, there is a high likelihood of one Reduced effectiveness of levodopa.
Will levodopa combined with MAO-A inhibitors, it can too critical increases in blood pressure come. For this reason, 2 weeks before starting levodopa therapy should be the MAO-A inhibitors are discontinued.
Will levodopa together with antihypertensive drugs ingested so it can become a orthostatic hypotension (Circulatory disorder) come.
Also interactions with levodopa were at the Taking phenytoin and papaverine observed. Here came one Decrease in the effectiveness of levodopa in the treatment of Parkinson's disease.
Side effects
Common side effects when taking levodopa are:
- Vomit
- nausea
- Cardiovascular disorders
This adverse drug reactions can be through the Combination of levodopa with decarboxylase inhibitors decrease.Will be a long-term therapy performed with Levodpoa, so it often happens Fluctuations in the effectiveness and disorders of the movement sequence.
The most extreme form here is that On-off phenomenon known at which it is through alternating phases of good mobility and complete rigidity comes. This is attributed to an extracellular dopamine concentration in the basal cells that is presumably not kept constant.
By Reatard tablets or the Combination of levodopa with dopamine antagonists can this Effect fluctuations are reduced.
