Parkinson Medications Information

 

Parkinson\'s Medications

Parkinson\'s disease, or paralysis agitans, is a chronic progressive disorder of the central nervous system (CNS), which is the result of damage to cells located in the basal ganglia of the brain. The term parkinsonism is used to describe the symptom complex which results from either the normal course of the disease, or from administration of drugs like the Phenothiazines, Butyrophenones, reserpine, methyldopa, procaine and tetrabenazine.

Drug therapy of parkinsonism aims towards augmentation of central dopaminergic function, or reduction of central cholinergic activity on this basis Antiparkinsonian drugs may be classified as
I. Dopaminergic agents
(a) Dopamine precursor (e.g., levodopa)
(b) Dopamine-releasing agent (e.g., amantadine)
(c) Dopamine receptor agonists (e.g., bromocriptine, pergolide)
(d) Inhibition of dopamine inactivation (e.g., selegilirte)

II. Anticholinergic and antihistaminic agents
(a) Anticholinergics (e.g., benztropine, biperiden)
(b) Antihistaminic (e.g., diphenhydramine)

Dopaminergic Agents Parkinson Medications

Benserazide
As the symptoms of Parkinson’s disease are related to the deficiency of striatal DA, replacement therapy in the form of levodopa, which is the metabolic precursor of DA, seems to be a logical therapeutic alternative. DA itself fails to cross the blood-brain barrier in adequate amounts, and is not effective in treating the disease. Levodopa (L-DOPA, 1- dihydroxyphenylalanine), the metabolic precursor of dopamine, penetrates the blood-brain barrier, and is converted in the brain, thereby replenishing the deficient neurotransmitter.

Carbidopa is a peripheral dopa decarboxylase inhibitor. It competes with the enzyme dopa decarboxyl thereby retarding the peripheral breakdown of L-DOPA.
Benserazide is another peripheral dopa decarboxylase inhibitor which is used in combination with levodopa in a ratio of 1: 4.

Amantadine

Amantadine is a synthetic antiviral agent, originally used for prophylaxis against the Asian strain of influenza. It also effectively relieves symptoms of parkinsonism, specially akinesia and rigidity.

Bromocriptine 
One of the newer drugs approved for the treatment of parkinsonism is the ergoline derivative, bromocriptine. It is a dopamine agonis acting directly on the postsynaptic dopamine receptors.

Pergolide 
Pergolide is another ergoline derivative, which is now available for adjunctive treatment with Carbidopa/levodopa in the symptomatic management of Parkinson’s disease.

Selegiline 
Physiologically, the enzyme MAO-B catalyzes the metabolism of dopamine in the brain. Selegiline (formerly deprenyl) irreversibly inhibits MAO-B enzyme in the nerve endings in the brain, thereby increasing the intraneural levels of dopamine.

Alzheimer’s Disease
Alzheimer’s disease (AD) is characterized by progressive impairment of memory and cognitive functions, leading to a complete vegetative state. It is a disease of the ageing population. Impairment of short-term memory (STM) is usually the first symptom of the disease, while long-term memory (LTM), i.e., retrieval of distant memories remains relatively preserved. As the disease progresses there is an additional loss of cognitive abilities, like ability to calculate, and to handle common objects and tools (ideomotor apraxia). This is followed by motor weakness, muscle contractures, and death due to complications of immobility like pneumonia and pulmonary embolism.
Patients of AD are very uncooperative and at times are helped by neuroleptics like promazine or haloperidol. Anxiolytics are of no help, and are pest avoided. Antimuscarinic drugs aggravate the condition.
Anticholinesterases. The reversible ACE inhibitor ph has shown some efficacy in improving cognitive function in Alzheimer type dementia.

Tacrine : Tacrine is an orally active amine that readily enters the CWS, and has a duration of effect of 6—8 hour in contrast to physostigmine with a duration of 1-2 hours.