AMANTADINE Drug Interactions: What You Need to Know

Drug Interactions Careful observation is required when amantadine hydrochloride is administered concurrently with central nervous system stimulants. Agents with anticholinergic properties may potentiate the anticholinergic-like side effects of amantadine. Coadministration of thioridazine has been reported to worsen the tremor in elderly patients with Parkinson’s disease, however, it is not known if other phenothiazines produce a similar response. Coadministration of Dyazide (triamterene/hydrochlorothiazide) resulted in a higher plasma amantadine concentration in a 61-year-old man receiving amantadine hydrochloride (Amantadine Hydrochloride, USP) 100 mg TID for Parkinson’s disease. 1 It is not known which of the components of Dyazide contributed to the observation or if related drugs produce a similar response. Coadministration of quinine or quinidine with amantadine was shown to reduce the renal clearance of amantadine by about 30%. The concurrent use of amantadine hydrochloride with live attenuated influenza vaccine (LAIV) intranasal has not been evaluated. However, because of the potential for interference between these products, LAIV should not be administered within 2 weeks before or 48 hours after administration of amantadine hydrochloride, unless medically indicated. The concern about possible interference arises from the potential for antiviral drugs to inhibit replication of live vaccine virus. Trivalent inactivated influenza vaccine can be administered at any time relative to use of amantadine hydrochloride. Carcinogenesis and Mutagenesis Long-term in vivo animal studies designed to evaluate the carcinogenic potential of amantadine hydrochloride have not been performed. In several in vitro assays for gene mutation, amantadine hydrochloride did not increase the number of spontaneously observed mutations in four strains of Salmonella typhimurium (Ames Test) or in a mammalian cell line (Chinese Hamster Ovary cells) when incubations were performed either with or without a liver metabolic activation extract. Further, there was no evidence of chromosome damage observed in an in vitro test using freshly derived and stimulated human peripheral blood lymphocytes (with and without metabolic activation) or in an in vivo mouse bone marrow micronucleus test (140 to 550 mg/kg; estimated human equivalent doses of 11.7 to 45.8 mg/kg based on body surface area conversion). Impairment of Fertility The effect of amantadine on fertility has not been adequately tested, that is, in a study conducted under Good Laboratory Practice (GLP) and according to current recommended methodology. In a three litter, non-GLP, reproduction study in rats, amantadine hydrochloride at a dose of 32 mg/kg/day (equal to the maximum recommended human dose on a mg/m 2 basis) administered to both males and females slightly impaired fertility. There were no effects on fertility at a dose level of 10 mg/kg/day (or 0.3 times the maximum recommended human dose on a mg/m 2 basis); intermediate doses were not tested. Failed fertility has been reported during human in vitro fertilization (IVF) when the sperm donor ingested amantadine 2 weeks prior to, and during the IVF cycle.

Pregnancy

The effect of amantadine on embryofetal and peri-postnatal development has not been adequately tested, that is, in studies conducted under Good Laboratory Practice (GLP) and according to current recommended methodology. However, in two non-GLP studies in rats in which females were dosed from 5 days prior to mating to Day 6 of gestation or on Days 7 to 14 of gestation, Symmetrel produced increases in embryonic death at an oral dose of 100 mg/kg (or 3 times the maximum recommended human dose on a mg/m 2 basis). In the non-GLP rat study in which females were dosed on Days 7 to 14 of gestation, there was a marked increase in severe visceral and skeletal malformations at oral doses of 50 and 100 mg/kg (or 1.5 and 3 times, respectively, the maximum recommended human dose on a mg/m 2 basis). The no-effect dose for teratogenicity was 37 mg/kg (equal to the maximum recommended human dose on a mg/m 2 basis). The safety margins reported may not accurately reflect the risk considering the questionable quality of the study on which they are based. There are no adequate and well- controlled studies in pregnant women. Human data regarding teratogenicity after maternal use of amantadine is scarce. Tetralogy of Fallot and tibial hemimelia (normal karyotype) occurred in an infant exposed to amantadine during the first trimester of pregnancy (100 mg P.O. for 7 days during the 6th and 7th week of gestation). Cardiovascular maldevelopment (single ventricle with pulmonary atresia) was associated with maternal exposure to amantadine (100 mg/d) administered during the first 2 weeks of pregnancy. Amantadine hydrochloride should be used during pregnancy only if the potential benefit justifies the potential risk to the embryo or fetus.

Nursing Mothers

Amantadine hydrochloride is excreted in human milk. Use is not recommended in nursing mothers.

Pediatric Use

The safety and efficacy of amantadine hydrochloride in newborn infants and infants below the age of 1 year have not been established. Usage in the Elderly Because amantadine hydrochloride is primarily excreted in the urine, it accumulates in the plasma and in the body when renal function declines. Thus, the dose of amantadine hydrochloride should be reduced in patients with renal impairment and in individuals who are 65 years of age or older. The dose of amantadine hydrochloride may need reduction in patients with congestive heart failure, peripheral edema, or orthostatic hypotension (see DOSAGE AND ADMINISTRATION ).

GOCOVRI is contraindicated in patients with end-stage renal disease (i.e., creatinine clearance below 15 mL/min/1.73 m 2 ) [see Clinical Pharmacology ( 12.3 )]. GOCOVRI is contraindicated in patients with end-stage renal disease ( 4 )

AND PRECAUTIONS Falling Asleep During Activities of Daily Living : Advise patients prior to treatment; ordinarily discontinue if occurs ( 5.1 ) Suicidality and Depression : Monitor patients for depressed mood, depression, or suicidal ideation or behavior ( 5.2 )

Hallucinations/Psychotic

Behavior: Patients with major psychotic disorder should ordinarily not be treated with GOCOVRI; observe patients for the occurrence of hallucinations throughout treatment, especially at initiation and after dose increases ( 5.3 ) Dizziness and Orthostatic Hypotension : Monitor patients for dizziness and orthostatic hypotension, especially after starting GOCOVRI or increasing the dose ( 5.4 ) Withdrawal-Emergent Hyperpyrexia and Confusion : Avoid sudden discontinuation ( 5.5 )

Corneal

Edema : Monitor patients for new changes in vision, including blurred vision, with or without eye pain, or vision loss. Taper and discontinue if corneal edema occurs ( 5.6 )

Impulse Control/Compulsive

Behaviors : Ask patients about increased gambling urges, sexual urges, uncontrolled spending or other urges; consider dose reduction or discontinuation if occurs ( 5.7 )

5.1 Falling Asleep During Activities of Daily Living and Somnolence Patients treated for Parkinson's disease have reported falling asleep while engaged in activities of daily living, including the operation of motor vehicles, which sometimes has resulted in accidents. Patients may not perceive warning signs, such as excessive drowsiness, or they may report feeling alert immediately prior to the event. In controlled clinical trials, somnolence and fatigue were reported as adverse reactions in 4% of patients treated with GOCOVRI 274 mg and 1% for placebo. Before initiating treatment with GOCOVRI, advise patients of the potential to develop drowsiness and specifically ask about factors that may increase the risk for somnolence with GOCOVRI, such as concomitant sedating medications or the presence of a sleep disorder. If a patient develops daytime sleepiness or episodes of falling asleep during activities that require full attention (e.g., driving a motor vehicle, conversations, eating), GOCOVRI should ordinarily be discontinued. If a decision is made to continue GOCOVRI, patients should be advised not to drive and to avoid other potentially dangerous activities. There is insufficient information to establish that dose reduction will eliminate episodes of falling asleep while engaged in activities of daily living or daytime somnolence.

5.2 Suicidality and Depression In controlled clinical trials, suicidal ideation or suicide attempt was reported in 2% of GOCOVRI-treated patients and 0% of placebo-treated patients. Depression or depressed mood was reported in 6% of GOCOVRI-treated patients and 1% of placebo-treated patients. Confusional state was reported in 3% of GOCOVRI-treated patients and 2% of placebo-treated patients. Apathy was reported in 2% of GOCOVRI-treated patients and 0% of placebo-treated patients. Monitor patients for depression, including suicidal ideation or behavior. Prescribers should consider whether the benefits outweigh the risks of treatment with GOCOVRI in patients with a history of suicidality or depression.

5.3 Hallucinations/Psychotic Behavior Patients with a major psychotic disorder should ordinarily not be treated with GOCOVRI because of the risk of exacerbating psychosis. In controlled trials, the incidence of patients who experienced visual hallucinations, auditory hallucinations, delusions, illusions, or paranoia was 25% in patients treated with GOCOVRI 274 mg, and 3% in placebo-treated patients. Hallucinations caused discontinuation of treatment in 8% of GOCOVRI-treated patients, and in 0% of placebo-treated patients. Observe patients for the occurrence of hallucinations throughout treatment, especially at initiation, and after dose increases.

5.4 Dizziness and Orthostatic Hypotension In controlled clinical trials, 29% of GOCOVRI-treated patients and 2% of placebo-treated patients experienced dizziness, syncope, orthostatic hypotension, presyncope, postural dizziness or hypotension. In GOCOVRI-treated patients, 3% discontinued study treatment because of dizziness, postural dizziness, or syncope, compared to 0% of placebo-treated patients. Monitor patients for dizziness and orthostatic hypotension, especially after starting GOCOVRI or increasing the dose. Concomitant use of alcohol when using GOCOVRI is not recommended <span class="opacity-50 text-xs">[see Drug Interactions ( 7.4 )]</span>.

5.5 Withdrawal-Emergent Hyperpyrexia and Confusion A symptom complex resembling neuroleptic malignant syndrome (characterized by elevated temperature, muscular rigidity, altered consciousness, and autonomic instability), with no other obvious etiology, has been reported in association with rapid dose reduction, withdrawal of, or changes in drugs that increase central dopaminergic tone. Abrupt discontinuation of GOCOVRI may cause an increase in the symptoms of Parkinson&apos;s disease or cause delirium, agitation, delusions, hallucinations, paranoid reaction, stupor, anxiety, depression, or slurred speech. It is recommended to avoid sudden discontinuation of GOCOVRI <span class="opacity-50 text-xs">[see Dosing Information ( 2.4 )]</span> .

5.6 Corneal Edema Corneal edema has been reported in patients taking amantadine. Symptoms include sudden onset of blurry vision, or progressive vision loss, with or without eye pain. Corneal involvement is usually bilateral. Onset can occur from a few weeks to several years after starting amantadine. Resolution of symptoms typically begins within weeks of amantadine cessation. However, corneal grafts have been required in some patients when the condition is not recognized. Permanent damage can occur if amantadine is continued. Ask patients if their vision has changed and obtain ophthalmologic examinations to rule out corneal edema should vision changes occur after initiation of therapy with GOCOVRI. If corneal edema occurs, taper and discontinue GOCOVRI <span class="opacity-50 text-xs">[see Dosage and Administration ( 2.4 )]</span> .

5.7 Impulse Control/Compulsive Behaviors Patients can experience intense urges to gamble, increased sexual urges, intense urges to spend money, binge eating, and/or other intense urges, and the inability to control these urges while taking one or more of the medications, including GOCOVRI, that increase central dopaminergic tone. In some cases, these urges were reported to have stopped when the dose was reduced or the medication was discontinued. Because patients may not recognize these behaviors as abnormal, it is important for prescribers to specifically ask patients or their caregivers about the development of new or increased gambling urges, sexual urges, uncontrolled spending, or other urges while being treated with GOCOVRI. Consider dose reduction or stopping the medication if a patient develops such urges while taking GOCOVRI.