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pharm quiz 4.5
Parkinson's disease
| Question | Answer |
|---|---|
| When does Parkinson's usually begin? | 45-64 years of age, but can begin as early as 30 |
| What is the progression of Parkinson's? | Begins with tremors on one side of the body, progresses to both sides, and then begins to effect ability to walk, until there is no control over body movement |
| What is the etiology of Parkinson's? | decrease of inhibitory dopaminergic neurons in the substantia nigra while acetylcholine is excitatory |
| Strategy of treatment for Parkinson's? | Balance D & Ach, aimed at restoring the effects or increasing levels of dopamine, may also include antagonizing or blocking the effects of Ach, can relive symptoms of the disease, but they do not affect the degeneration of D-neurons or reverse disease |
| Drug treatment for Parkinson's- 4 categories, 2 loners | levodopa / carbidopa (Sinemet, Sinemet CR, Parcopa®), Catechol Omethyltransferase Inhibitors (COMT-inhibitors), Dopamine Receptor Agonists, Monoamine Oxidase-B Inhibitor, Amantadine (Symmetrel), Anticholinergic Agents |
| levodopa / carbidopa (Sinemet, Sinemet CR, Parcopa®) information | carbidopa blocks decarboxylase from converting levodopa to dopamine in the periphery, allowing levadopa to be converted and used in the CNS |
| Adverse Effects for levodopa / carbidopa (Sinemet, Sinemet CR, Parcopa®): -4 categories | Peripheral (N/V, constipation, OrthoHypoTN, dysrhythmias), CNS (high doses; restlessness, insomnia, confusion, psych disturbance, Dyskinesias (chorea, athetosis, systonia, tremor, tics, myoclonus), On-off phenomenon (bradykinesia vs dyskinesias) |
| Drug interactions with levodopa / carbidopa (Sinemet, Sinemet CR, Parcopa®): -3 | Dopamine blockers may worsen Parkinson's symptoms, antipsychotics blocking D-receptors (1st gen.), some entiemetics such as metodropamide (Reglan), prochlorperazine (Compazine), and promethazine (Phenergan) block D-receptor in "vomit center" |
| Catechol Omethyltransferase Inhibitors (COMT-inhibitors) Examples: -4 | entacapone (Comtan), levodopa, carbidopa, entacapone (Stalevo®) |
| Mechanism of Action for COMT-inhibitors | Only about 5-10% of orally administered levodopa reaches the brain despite co-administration with carbidopa, COMT-inhibitors target another metabolizer of levodopa, the enzyme COMT |
| Therapeutic uses for COMT-inhibitors | Used in conjunction with levodopa/carbidopa to reduce on/off phenomenon, Leads to more sustained & consistent CNS dopamine levels |
| Adverse effects for COMT-inhibitors | Peripheral & CNS domaninergic adverse effects Diarrhea (10-18%) & hallucinations (5-10%) |
| Dopamine Receptor Agonists Examples: -4 | rotigotine (Neupro),ropinirole (Requip), pramipexole (Mirapex), bromocriptine (Parlodel) |
| Dopamine Receptor Agonists | Directly stimulate the CNS dopamine receptors |
| Dopamine Receptor Agonists | Appropriate monotherapy or in combination with levodopa/carbidopa for synergy, Pramipexole & ropinirole are FDA approved for restless leg syndrome. RLS is an unpleasant sensation in the legs and uncontrollable urge to move when at rest. |
| Dopamine Receptor Agonists | Same peripheral & CNS dopaminergic adverse effects |
| Monoamine Oxidase-B Inhibitor Examples: -2 | rasagiline (Azilect) selegiline (Eldepryl, Zelapar rapid dissolving) |
| Mechanism of Action for MOA-B Inhibitor | Selectively inhibits the enzyme that breaks down dopamine: does not inhibit MAO-A (breaks down NE, serotonin, & tyramine), does not have the food & drug interactions. Remember, at higher doses, it may lose its selectivity |
| Therapeutic uses for MOA-B Inhibitor | This drug enhances the actions of levodopa & can allow smaller doses of levodopa to be given |
| Adverse Effects & drug interactions for MOA-B Inhibitor | Most common adverse effect is insomnia. Minimize this by not giving any doses after noon, Same peripheral & CNS dopaminergic adverse effects Avoid use with dextromethorphan, meperidine, pseudoephedrine (hyperpyrexia) |
| Mechanism of Action for Amantadine (Symmetrel) | Discovered as a side benefit during studies of this drug as an antiviral agent, Enhance the synthesis, release, or re-uptake of dopamine from the surviving neurons |
| Therapeutic uses of Amantadine (Symmetrel) | Less efficacious than levodopa & tolerance rapidly develops Used to treat MILD symptoms |
| Adverse Effects of Amantadine (Symmetrel) | Same peripheral & CNS dopaminergic adverse effects |
| Anticholinergic Agents examples: -3 | benztropine (Cogentin) trihexyphenidyl (Artane) procyclidine (Kemadrin) |
| Mechanism of Action for Anticholinergic Agents | Pharmacologically similar to atropine: Preferentially antagonize ACh in substantia nigra |
| Therapeutic uses of Anticholinergic Agents | Treat tremor & rigidity better than bradykinesia, May be used alone in very MILD Parkinson’s. They are almost always used as adjunctive therapy with a dopamine active medication, most commonly used to treat antipsychotic induced EPSE |
| Adverse Effects of Anticholinergic Agents | Anti-SLUD: Dry mouth Blurred vision Constipation Urinary retention Tachycardia CNS: memory loss |
Created by:
hcress08
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