Amantadine adverse effects

Low affinity use-dependent NMDA recqrtor antagonists meet the criteria for safe administration into patients. Drugs like amantadine and memantine have modest effects on Parkinson s disease and are used as initial therapy or as adjunct to l-DOPA. Their adverse effects include dizziness, lethargy and sleep disturbance. 

The site of action for Memantine is the central nervous system (CNS) and it has CNS affinity. Amantadine and Rimantadine can penetrate to the CNS and cause some adverse effects. 

Keyset LA, Karl M, Nafziger AN, Bertino JS Jr. (2000) Comparison of central nervous system adverse effects of amantadine and rimantadine used as sequential prophylaxis of influenza a in elderly nursing home patients. Arch Intern Med 160 1485-1488... 

Amantadine (see Chapter 21, Section Ill.b.l) is a tricyclic symmetric adamantanamine. It inhibits the uncoating stage which takes place for binding of the virus to cells, of the influenza-A virus. It is used prophylactically for influenza-A infection, and when given within 24 hours of onset for active influenza-A. It shows good oral absorption and is excreted in the urine with an elimination half-life of about 12 hours. The adverse effects are mainly on the CNS and include insomnia, restlessness, nervousness and depression. 

Amantadine was originally introduced as an antiviral compound (see Chapter 50), but it is modestly effective in treating symptoms of parkinsonism. It is useful in the early stages of parkinsonism or as an adjunct to levodopa therapy. Its mechanism of action in parkinsonism is not clear, but amantadine may affect dopamine release and reuptake. Additional sites of action may include antagonism at muscarinic and A-methyl-D-aspartate (NMDA) receptors. Adverse effects include nausea, dizziness, insomnia, confusion, hallucinations, ankle edema, and livedo reticularis. Amantadine and the anticholinergics may exert additive effects on mental functioning. 

For each patient, select the drug that most likely caused the adverse effect Acyclovir Amantadine Dideoxycytldlne Foscarnet Ganciclovir Idoxuridine... 

Dicyclomine (Bentyl) [Anrimuscarinic, GI Anrispasmodic/ Anticholinergic] Uses Functional IBS Action Smooth-muscle relaxant Dose Adults. 20 mg PO qid T to 160 mg/d max or 20 mg EM q6h, 80 mg/d - qid then T to 160 mg/d, max 2 wk Feds. Infants >6 mo 5mg/dose tid-qid Children 10 mg/dose tid-qid Caution [B, -] Contra Infants <6 mo, NAG, MyG, severe UC, BOO Disp Caps, tabs, syrup, inj SE Anticholinergic SEs may limit dose Interactions T Anticholinergic effects W/ anticholinergics, antihistamines, amantadine, MAOIs, TCAs, phenothiazides T effects OF atenolol, digoxin X effects H7 antacids X effects OF haloperidol, ketoconazole, levodopa, phenothiazines EMS Avoid procainamide usage, may T adverse effects may T effects of digoxin, monitor... 

The primary adverse effects associated with amantadine are orthostatic hypotension, CNS disturbance (e.g., depression, confusion, hallucinations), and patches of skin discoloration on the lower extremities (livedo reticularis). However, these side effects are relatively mild compared to those of other anti-Parkinson drugs and are usually reversed by altering the drug dosage. 

Adverse Effects. These drugs may produce central nervous system (CNS) symptoms such as confusion, loss of concentration, mood changes, nervousness, dizziness, and light-headedness. These symptoms may be especially problematic in elderly patients. Excessive doses of amantadine and rimantadine may increase the... 

Adverse effects Amantadine s side effects are mainly associated with the CNS. Minor neurologic symptoms include insomnia, dizziness, and ataxia. More serious side effects have been reported (for example, hallucinations, seizures). The drug should be employed cautiously in patients with psychiatric problems, cerebral atherosclerosis, renal impairment, or epilepsy. Rimantadine causes fewer CNS reactions since it does not efficiently cross the blood-brain barrier. Amantadine and rimantadine should be used with caution in pregnant and nursing mothers, because they have been found to be embryotoxic and teratogenic in rats. 

Memantine is an amantadine derivative that has been studied in patients with Parkinson s disease. Its adverse effects include agitation, restlessness, insomnia, pronounced delirious states, and muscular hypotonia. All were reversible after dosage reduction or withdrawal. 

Rimantadine hydrochloride, an alpha-methyl derivative of amantadine (alpha-methyl-l-adamantane methylamine hydrochloride), is more active than amantadine against influenza A viruses in vitro and in laboratory animals. It is an alternative to amantadine for the prevention and treatment of influenza A virus infections in adults and for the prevention of influenza in children. Adverse effects have been considered to be less common with rimantadine (SEDA-8, 143), and it is generally tolerated better than amantadine, because it causes fewer nervous system adverse effects (1). Unfortunately, rimantadine is more costly, which has led many institutions to develop influenza treatment guidelines. Both drugs work by blocking the M2 ion channel, which is needed to affect a pH change that helps to initiate viral uncoating. 

Multiple sclerosis Beta interferons, glatiramer acetate, glucocorticoids, antispasmodics, amantadine, stimulants, immunosuppressants Number of exacerbations, self-injection technique, injection site reactions, amount of spasticity, amount of fatigue, CBC and infections (immunosuppressants), medication-specific adverse effects... 

Concomitant nse with amantadine may amplify trihexyphenidyl s anticholinergic adverse effects, causing confusion and haUncinations. Concomitant use with haloperidol or phenothiazines may decrease the antipsychotic effectiveness of these drugs, possibly from direct CNS antagonism concomitant phenothiazine nse also increases the risk of anticholinergic adverse effects. 

The use of dopaminergic agents in combination with antimuscarinic drugs is common in the treatment of parkinsonism. Bromocriptine does not complicate treatment with antimuscarinic drugs or amantadine. If combined with levodopa, bromocriptine should be used in reduced doses to avoid intolerable adverse effects. Confusion, delusions, and hallucinations occur more frequently with bromocriptine than with levodopa. Bromocriptine does not require bioactivation for its antiparkinson effects. The answer is (C). 

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