Parkinson's Disease Pharmacology III (PHPG 4313) - Lecture Notes PDF

PHARMACOLOGY III PHPG 4313 UNIT 1 :NERVOUS SYSTEM Parkinson’s disease  Learning outcome : Identify parkinson’s disease Describe symptoms of parkinson’s disease Explain the neurochemical basis for degenerative disease of the CNS, focusing on the roles of important neu...

PHARMACOLOGY III PHPG 4313 UNIT 1 :NERVOUS SYSTEM Parkinson’s disease  Learning outcome : Identify parkinson’s disease Describe symptoms of parkinson’s disease Explain the neurochemical basis for degenerative disease of the CNS, focusing on the roles of important neurotransmitters in the brain. For each of the drug class, know the drug examples, and explain the mechanism of action and important adverse effects for each. Parkinson’s disease a degenerative disorder of the CNS caused by death of neurons that produce the brain neurotransmitter dopamine. progressive neurological disorder of muscle movement Most cases involve people over the age of 65, among whom the incidence is about 1 in 100 individuals Parkinson’s symptoms Symptoms of parkinsonism develop due to the degeneration and destruction of dopamine producing neurons found within the brain. When not enough dopamine is released, this neurotransmitter cannot make contact with corpus striatum, an area responsible for controlling unconscious muscle movement. Balance, posture, muscle tone, and involuntary muscle movement depend on the proper balance of dopamine (inhibitory) and acetylcholine (stimulatory) in the corpus striatum. If dopamine is absent, acetylcholine is able to stimulate this area more. Parkinson’s symptoms For this reason, drug therapy for parkinsonism focuses not only on restoring dopamine function, but also on blocking the effect of acetylcholine within the corpus striatum. The symptoms of parkinson’s disease are summarized as follows : Tremors : The hands and head develop shakiness when at rest. Muscle rigidity : Patients often have difficulty bending over or moving limbs. Bradykinesia : Patients may have difficulty chewing, swallowing, or speaking. Postural instability : Patients may easily lose their balance  B. Strategy of treatment In addition to an abundance of inhibitory dopaminergic neurons, the neostriatum is also rich in excitatory cholinergic neurons that oppose the action of dopamine. Many of the symptoms of parkinsonism reflect an imbalance between the excitatory cholinergic neurons and the greatly diminished number of inhibitory dopaminergic neurons. Therapy is aimed at restoring dopamine in the basal ganglia and antagonizing the excitatory effect of cholinergic neurons, thus reestablishing the correct dopamine/acetylcholine balance. Antiparkinsonism agents Antiparkinsonism agents are given to restore the balance of dopamine and acetylcholine in the corpus striatum of the brain. These drugs include dopaminergic agents and anticholinergics. Drugs used in Parkinson’s disease  A. Dopaminergic agents Dopaminergic drugs are used to increase dopamine levels in the corpus striatum. Levodopa is a precursor of dopamine Go to fullsize image synthesis. Supplying it directly lead to increased synthesis of dopamine within the nerve terminals. Levodopa can cross the blood-brain barrier, but dopamine cannot. Therefore, dopamine by itself is not used for therapy. The effectiveness of levodopa can be “boosted” by combining it with carbidopa. Anticholinergic The anticholinergics now used produce fewer side effects. But they still cause autonomic effects such as dry mouth, tachycardia, and constipation that are troublesome. This agent act by blocking the effect of acetylcholine, inhibit the overactivity of this neurotransmitter in the corpus striatum of the brain.  C. Antimuscarinics Muscarinic antagonists produce a modest improvement in the early stages of Parkinson’s disease, but the bradykinesia that is responsible for most of the functional disability responds least well. Furthermore, adverse effects are common and include dry mouth, urinary retention and constipation. More seriously, antimuscarinics can affect memory and concentration and precipitate an organic confusional state with visual hallucinations, especially in elderly or dementing patients. The main use of these drugs is in the treatment of drug‐induced parkinsonism Tutorial Find 2 example drugs for each group. Find the information about the drug. List all the information in the table. ( use mims as your reference) Drug name Drug group Indication MOA Dose Adverse Effect Contraindication Drug interaction Food interaction storage