The motor symptoms of Parkinson's disease (PD) are caused primarily by degeneration of dopaminergic neurons in the substantia nigra. The nonmotor symptoms of the disease are thought to be caused by degeneration of other neurotransmitter systems. No disease-modifying drugs are available for treatment of PD.

View the Comparison Table: Drugs for Parkinson's Disease

The FDA has approved istradefylline (Nourianz — Kyowa Kirin), an oral adenosine A_2A receptor antagonist, for use as an adjunct to carbidopa/levodopa in adults with Parkinson's disease (PD) who experience "off" episodes. Istradefylline is the first adenosine A_2A receptor antagonist to be approved in the US; it has been available in Japan since 2013.

The FDA has approved Inbrija (Acorda), an orally inhaled dry-powder formulation of levodopa, for intermittent treatment of "off" episodes in patients with Parkinson's disease (PD) being treated with carbidopa/levodopa (Sinemet, and others).

The motor symptoms of Parkinson's disease (PD) are caused primarily by degeneration of dopaminergic neurons in the substantia nigra. The nonmotor symptoms of the disease are thought to be caused by degeneration of other neurotransmitter systems.

View the Comparison Table: Drugs for Parkinson's Disease

The FDA has approved a new formulation of carbidopa/levodopa (Rytary – Impax) in extended-release capsules for treatment of Parkinson’s disease (PD).

The motor symptoms of Parkinson's disease (PD) are caused primarily by progressive degeneration of dopaminergic neurons in the substantia nigra. The non-motor symptoms of the disease are thought to be caused by degeneration of other neurotransmitter systems.

Gabapentin enacarbil (Horizant – GlaxoSmithKline), a new extended-release (ER) tablet formulation of gabapentin, has been approved by the FDA for treatment of moderate-to-severe restless legs syndrome (RLS). The immediate-release (IR) formulation of gabapentin (Neurontin,and others), which is approved for treatment of epilepsy and postherpetic neuralgia, has been used for many years to treat RLS. Another ER tablet formulation of gabapentin (Gralise) has been approved by the FDA for treatment of postherpetic neuralgia.

Parkinson’s disease (PD) is caused primarily by progressive degeneration of dopamine-containing neurons in the substantia nigra. Dopamine itself cannot be used to treat PD because it does not cross the blood-brain barrier.

Deep brain stimulation (DBS) is increasingly used to treat advanced Parkinson's disease (PD), but few controlled clinical trials have been published. New evidence from a large controlled study has recently become available.

Many drugs can cause psychiatric symptoms, but a causal connection is often difficult to establish. Psychiatric symptoms that emerge during drug treatment could also be due to the underlying illness, previously unrecognized psychopathology, or psychosocial factors. The withdrawal of some drugs can cause symptoms such as anxiety, psychosis, delirium, agitation or depression.

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ParkinsonÆs disease (PD) is caused primarily by progressive degeneration of dopamine-containing neurons in the substantia nigra. Dopamine itself cannot be used to treat PD because it does not cross the bloodbrain barrier.

An orally dissolving, immediate-release tablet formulation of carbidopa/levodopa (Parcopa - Schwarz) that can be taken without water is now available for treatment of Parkinson's disease.

Apomorphine (Apokyn - Mylan/Bertek), an injected non-ergot dopamine agonist, was recently approved by the FDA for intermittent subcutaneous (SC) treatment of hypomobility ("off" episodes) in patients with advanced Parkinson's disease. It has been available in Europe for many years.

Parkinson's disease is caused by progressive degeneration of dopamine-containing neurons in the substantia nigra. Dopamine itself cannot be used to treat Parkinson's disease because it does not cross the blood-brain barrier.

Levodopa combined with carbidopa (Sinemet, and others) is the most widely used treatment for patients with Parkinson's disease, but after 2 to 5 years most patients develop troublesome complications (Treatment Guidelines from The Medical Letter 2004; 2:41). The newest treatment for Parkinson's disease patients with end-of-dose "wearing-off" is Stalevo (Novartis), a combination of the catechol-O-methyltransferase (COMT) inhibitor entacapone (Comtan) with 3 different doses of levodopa/carbidopa. The rationale for Stalevo is that it permits some patients to take only one pill rather than two.

Many drugs can cause psychiatric symptoms, but a causal connection is often difficult to establish. Psychiatric symptoms that emerge during drug treatment may also be due to the underlying illness, previously unrecognized psychopathology, or psychosocial factors. The withdrawal of some drugs can cause symptoms such as anxiety, psychosis, delirium, agitation or depression.

Recent articles in the press have trumpeted a new era in the management of Parkinson's disease: dopamine agonists have now replaced levodopa for initial treatment.

Entacapone (Comtan), a catechol-O-methyltransferase (COMT) inhibitor, has been approved by the FDA for adjunctive use with levodopa/carbidopa in patients with Parkinson's disease who have end-of-dose "wearing off"symptoms.

Tolcapone (Tasmar - Roche), a dihydroxy-methyl-nitrobenophenone, has been marketed as an adjunct to levodopa/carbidopa (Sinemet, and others) for treatment of Parkinson's disease in both stable patients and those with end-of-dose "wearing off"of levodopa.

Approaches to treatment of Parkinson's disease have changed in recent years. Previously, the only goal was to treat symptoms with levodopa or other drugs. A new approach is to try to slow progression of the disease. (This issue is superseded by 1999 Drugs of Choice.)

Bupropion (Wellbutrin - Burroughs Wellcome) was recently marketed in the USA for treatment of depression. First approved by the Food and Drug Administration in late 1985, the drug was withdrawn from the market in early 1986 because of a high incidence of seizures in one study.

Levodopa combined with carbidopa (Sinemet) is the treatment of choice for Parkinson's disease (Medical Letter, 30:113, 1988). After prolonged treatment, however, the symptoms of the disease often become difficult to manage. The benefit from each dose becomes shorter (the 'wearing-off' effect), sudden fluctuations occur between mobility and immobility (the 'on-off' phenomenon), and abnormal involuntary movements (dyskinesias) may become frequent. The dopamine agonist bromocriptine (Parlodel) can ameliorate some of these effects. Two new drugs, pergolide (Permax - Lilly), another dopamine agonist, and selegiline (Eldepryl - Somerset), a selective type B monoamine oxidase (MAO) inhibitor previously known as deprenyl, were recently approved by the US Food and Drug Administration for use with levodopa-carbidopa in patients with difficult-to-manage Parkinson's disease.

Patients with Parkinson's disease have a deficiency of the neurotransmitter dopamine, a catecholamine. Dpamine itself cannot be used to treat the disease because it does not cross the blood-brain barrier, but its metabolic precursor, levodopa, does cross into the brain and is converted to dopamine by a decarboxylase present both in the brain and in the intestinal tract (JM Cedarbaum, Clin Pharmacokinet, 13:141, 1987).