L-dopa

German: L-Dopa
Synonym: levodopa
Abreviation for: 3,4-Dihydroxy-Phenylalanin

1 Definition

L-dopa, also referred to as levodopa is a substance created by the hydroxylation of tyrosine. It serves as a precursor for various biologically relevant substances, amongst others melanin, dopamine, adrenaline and noradrenaline.

2 Mechanism of action

L-dopa itself already has an agonistic effect on the adrenergic receptors. It is capable of passing through the blood-brain barrier because of the presence of a primary active transporter.

3 Pharmacokinetics

L-dopa is administered as a prodrug and is given in combination with a DOPA decarboxylase inhibitor. This inhibitor prevents the metabolisation of the L-dopa before entering the CNS. Only after its passage through the blood-brain barrier, which the DOPA decarboxylase inhibitor is prevented of doing, it is decarboxylated and becomes the actual active metabolite dopamine.

4 Indication

L-dopa is given as a therapeutic substitution of dopamine in case of Parkinson’s disease. It represents one of the most important antiparkinsonian medications. It is especially important for the treatment of Parkinson’s disease in an advanced age.

5 Interactions

The simultaneous application of reserpine, neuroleptic drugs, opiods, antacids, iron preparations and vitamin B6 in high dosages can lead to a weakening of the effect of L-dopa.

Caffeine leads to an accelerated and increased effect of L-dopa.