Wearing off effects

Levodopa is widely used for treatment of all types of parkinsonism except those associated with antipsychotic drug therapy. However, as parkinsonism progresses, the duration of benefit from each dose of levodopa may shorten (wearing-off effect). Patients can also develop sudden, unpredictable fluctuations between mobility and immobility (on-off effect). In a matter of minutes, a patient enjoying normal or nearly normal mobility may suddenly develop a severe degree of parkinsonism. These symptoms are likely due to the... 

It is a selective MAO-B inhibitor, which is predominant in brain and blood platelets. It retards intracerebral degradation of dopamine. It is used with levodopa in early cases of parkinsonism. It prolongs levodopa action, attenuates motor fluctuations and decreases wearing off effect. But clinical benefits are short lived (6-24 months). 

A 36-year-old woman with a 4-year history of Parkinson s disease, who had been taking pergolide 3 mg/day and levodopa 200 mg/day continued to take it during pregnancy. The end-of-dose wearing-off effect completely disappeared, and reappeared at their previous intensity after delivery. There were no adverse effects in the mother. The baby was healthy at birth and remained so at the time of the report, at the age of 13 months. 

Internal antistats are considered permanent antistats. This permanence is based on the concept that most plastic products are disposable, so that the antistat is not required to last long. The antistatic effectiveness of an internal antistat can decrease over time. One study showed large increases in surface resistivity on antistatic bags stored at 71 °C for six months. Antistatic bags stored at room temperature showed only a small increase in surface resistivity (137). Loss of antistatic effectiveness is attributed to the volatility of the antistatic agent. The antistat does not easily wear off the plastic, but it can be removed with solvents and/or repeated wear. 

As part of the ongoing assessment during the administration of naloxone, the nurse monitors the blood pressure, pulse, and respiratory rate at frequent intervals, usually every 5 minutes, until the patient responds. After the patient has shown response to the drug, the nurse monitors vital signs every 5 to 15 minutes. The nurse should notify tlie primary healdi care provider if any adverse drug reactions occur because additional medical treatment may be needed. The nurse monitors die respiratory rate, rhydun, and depdi pulse blood pressure and level of consciousness until the effects of die narcotics wear off. 

In Britain and America the most common form of cocaine is as a white crystalline powder. Most users sniff it up the nose, often through a rolled banknote or straw, but it can also be made into a solution and injected. Crack is a smokable form of cocaine made into small lumps or rocks . It is usually smoked but can also be prepared for injection. Because it is such a fast-acting drug and the powerful effects wear off quickly, repeated use is common, and since cocaine is a relatively expensive drug it has become closely associated with a rich lifestyle. 

Response fluctuations occur with disease progression as the patient s dopamine reserves are depleted in the brain and as a complication of PD treatment. Motor fluctuations include delayed peak response, early wearing off, random unpredictable on-off, and freezing. Dyskinesias include chorea, dystonia, and diphasic dyskinesia. Wearing off can be visualized by imagining the therapeutic window of dopamine narrowing over time. The therapeutic window is defined as the minimum effective concentration of dopamine required to control PD symptoms (on without dyskinesia) and the maximum concentration before experiencing side effects from too much dopamine (on with dyskinesia). Early in the disease, a dose of... 

Initial response to short-acting stimulant formulations (e.g., methylphenidate and dextroamphetamine) is seen within 30 minutes and can last for 4 to 6 hours.13,14 This short duration of effect frequently requires that short-acting stimulant formulations be dosed at least twice daily, thus increasing the chance of missed doses and non-compliance. Further, patients using any stimulant formulation but especially shortacting formulations can experience a rebound effect of ADHD symptoms as the stimulant wears off.14... 

Physical effects of high doses of ketamine include decreased respiration and heart rate, increased blood pressure, and the possibility of vomiting and convulsions. These can lead to cardiac and respiratory arrest, coma, and death. The risk of ketamine overdose is much greater when it is mixed with other drugs such as alcohol, Ecstasy, caffeine, or cocaine. Overdoses of ketamine have been reported when people boost the drug (take another dose before the first dose wears off) to prolong its psychedelic effects. 

Ketamine is rapidly metabolized by the body, so the hallucinogenic effects of ketamine wear off within an hour or so after taking the drug. However, users say they often experience repeated flashbacks, or sudden memories of the visions or feelings experienced while on the drug. These flashbacks can persist for days, weeks, months, or even a year after a particular trip. 

Hypoventilation Monitor patients who have received flumazenil for the reversal of benzodiazepine effects (after conscious sedation or general anesthesia) for resedation, respiratory depression or other residual benzodiazepine effects for an appropriate period (120 minutes or less) based on the dose and duration of effect of the benzodiazepine employed, because flumazenil has not been established as an effective treatment for hypoventilation due to benzodiazepine administration. Flumazenil may not fully reverse postoperative airway problems or ventilatory insufficiency induced by benzodiazepines. In addition, even if flumazenil is initially effective, such problems may recur because the effects of flumazenil wear off before the effects of many benzodiazepines. 

Ambulatory patients Effects may wear off before a long-acting benzodiazepine is completely cleared from the body. 

Parkinson s disease As an adjunct to levodopa/carbidopa to treat patients with idiopathic Parkinson s disease who experience the signs and symptoms of end-of-dose wearing-off. The effectiveness of entacapone has not been systematically evaluated in patients with idiopathic Parkinson s disease who do not experience end-of-dose wearing-off. ... 

Tolerance may occur which means that the effect of some AEDs may wear off with time (benzodiazepines, barbiturates, vigabatrin). There are exceptional cases where refractory epilepsy escapes... 

Geriatric Considerations - Summary Levodopa is a precursor to dopamine and is converted to dopamine in the CNS. Carbidopa decreases peripheral conversion and increases CNS concentrations of levodopa. While sustained-release forms may be helpful in decreasing the wearing-off of levodopa effectiveness, there maybe little advantage over immediate-release preparations. This drug combination is often used as initial therapy for Parkinson s disease. 

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