Pk-Merz

Pk-Merz - General Information

An antiviral that is used in the prophylactic or symptomatic treatment of influenza A. It is also used as an antiparkinsonian agent, to treat extrapyramidal reactions, and for postherpetic neuralgia. The mechanisms of its effects in movement disorders are not well understood but probably reflect an increase in synthesis and release of dopamine, with perhaps some inhibition of dopamine uptake. [PubChem]

Pharmacology of Pk-Merz

Pk-Merz is an antiviral drug which also acts as an antiparkinson agent, for which it is usually combined with L-DOPA when L-DOPA responses decline (probably due to tolerance). It is a derivate of adamantane, like a similar drug rimantadine. The mechanism of action of amantadine in the treatment of Parkinson's disease and drug-induced extrapyramidal reactions is not known. It has been shown to cause an increase in dopamine release in the animal brain, and does not possess anticholinergic activity.

Pk-Merz for patients

WARNINGS

Deaths

Deaths have been reported from overdose with amantadine. The lowest reported acute lethal dose was 2 grams. Acute toxicity may be attributable to the anticholinergic effects of amantadine. Drug overdose has resulted in cardiac, respiratory, renal or central nervous system toxicity. Cardiac dysfunction includes arrhythmia tachycardia and hypertension.

Suicide Attempts

Suicide attempts, some of which have been fatal, have been reported in patients treated with amantadine, many of whom received short courses for influenza treatment or prophylaxis. The incidence of suicide attempts is not known and the pathophysiologic mechanism is not understood. Suicide attempts and suicidal ideation have been reported in patients with and without prior history of psychiatric illness. Amantadine can exacerbate mental problems in patients with a history of psychiatric disorders or substance abuse. Patients who attempt suicide may exhibit abnormal mental states which include disorientation, confusion, depression, personality changes, agitation, aggressive behavior, hallucinations, paranoia, other psychotic reactions and somnolence or insomnia. Because of the possibility of serious adverse effects, caution should be observed when prescribing amantadine to patients being treated with drugs having CNS effects, or for whom the potential risks outweigh the benefit of treatment. Because some patients have attempted suicide by overdosing with amantadine, prescriptions should be written for the smallest quantity consistent with good patient management.

CNS Effects

Patients with a history of epilepsy of other "seizures" should be observed closely for possible increased seizure activity.

Patients receiving amantadine who note central nervous system effects of blurring of vision should be cautioned against driving or working in situations where alertness and adequate motor coordination are important.

Other

Patients with a history of congestive heart failure or peripheral edema should be followed closely as there are patients who developed congestive heart failure while receiving amantadine.

Patients with Parkinson's disease improving on amantadine should resume normal activities gradually and cautiously, consistent with other medical considerations, such as the presence of osteoporosis or phlebothrombosis.

Pk-Merz Interactions

Careful observation is required when amantadine is administered concurrently with central nervous system stimulants.

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 triamterene and hydrochlorothiazide capsules resulted in a higher plasma amantadine concentration in a 61 year old man receiving amantadine (amantadine hydrochloride) 100 mg TID for Parkinson's disease.¹ It is not known which of the components of triamterene and hydrochlorothiazide capsules contributed to the observation or if related drugs produce a similar response.

Pk-Merz Contraindications

Amantadine hydrochloride is contraindicated in patients with known hypersensitivity to the drug.

Additional information about Pk-Merz

Pk-Merz Indication: For the chemoprophylaxis, prophylaxis, and treatment of signs and symptoms of infection caused by various strains of influenza A virus. Also for the treatment of parkinsonism and drug-induced extrapyramidal reactions.
Mechanism Of Action: The mechanism of its antiparkinsonic effect is not fully understood, but it appears to be releasing dopamine from the nerve endings of the brain cells, together with stimulation of norepinephrine response. The antiviral mechanism seems to be unrelated. The drug interferes with a viral protein, M2 (an ion channel), which is needed for the viral particle to become "uncoated" once it is taken inside the cell by endocytosis.
Drug Interactions: Bendroflumethiazide The diuretic increases the adverse effects of amantadine
Benzthiazide The diuretic increases the adverse effects of amantadine
Chlorothiazide The diuretic increases the adverse effects of amantadine
Cyclothiazide The diuretic increases the adverse effects of amantadine
Donepezil Possible antagonism of action
Galantamine Possible antagonism of action
Hydrochlorothiazide The diuretic increases the adverse effects of amantadine
Hydroflumethiazide The diuretic increases the adverse effects of amantadine
Indapamide The diuretic increases the adverse effects of amantadine
Memantine Increased risk of CNS adverse effects with this association
Methyclothiazide The diuretic increases the adverse effects of amantadine
Metolazone The diuretic increases the adverse effects of amantadine
Triamterene The diuretic increases the adverse effects of amantadine
Trichlormethiazide The diuretic increases the adverse effects of amantadine
Rivastigmine Possible antagonism of action
Polythiazide The diuretic increases the adverse effects of amantadine
Quinethazone The diuretic increases the adverse effects of amantadine
Food Interactions: Avoid alcohol.
Take without regard to meals.
Generic Name: Amantadine
Synonyms: Amantadine HCL; Adamantamine; Adamantanamine; Adamantylamine; Amantadine Base; Amantidine; Aminoadamantane; 1-aminoadamantane
Drug Category: Analgesics, Non-Narcotic; Antiparkinson Agents; Antiviral Agents; Dopamine Agents
Drug Type: Small Molecule; Approved

Other Brand Names containing Amantadine: Endantadine; Gen-Amantadine; Mantadine; Pk-Merz; Symadine; Symmetrel;
Absorption: Amantadine is well absorbed orally from the gastrointestinal tract.
Toxicity (Overdose): Deaths have been reported from overdose with amantadine. The lowest reported acute lethal dose was 2 grams. Drug overdose has resulted in cardiac, respiratory, renal or central nervous system toxicity. Cardiac dysfunction includes arrhythmia, tachycardia and hypertension. Pulmonary edema and respiratory distress (including ARDS) have been reported. Renal dysfunction including increased BUN, decreased creatinine clearance and renal insufficiency can occur. Central nervous system effects that have been reported include insomnia, anxiety, aggressive behavior, hypertonia, hyperkinesia, tremor, confusion, disorientation, depersonalization, fear, delirium, hallucination, psychotic reactions, lethargy, somnolence and coma. Seizures may be exacerbated in patients with prior history of seizure disorders. Hyperthermia has also been observed in cases where a drug overdose has occurred.
Protein Binding: Approximately 67% bound to plasma proteins over a concentration range of 0.1 to 2.0 µg/mL.
Biotransformation: No appreciable metabolism, although negligible amounts of an acetyl metabolite have been identified.
Half Life: Mean half-lives ranged from 10 to 14 hours, however renal function impairment causes a severe increase in half life to 7 to 10 days.
Dosage Forms of Pk-Merz: Capsule Oral
Syrup Oral
Chemical IUPAC Name: adamantan-1-amine
Chemical Formula: C10H17N
Amantadine on Wikipedia: https://en.wikipedia.org/wiki/Amantadine
Organisms Affected: Humans and other mammals; Various viruses