Regonol


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Regonol

 [reg´o-nōl]
trademark for preparations of pyridostigmine bromide, a cholinesterase inhibitor used in treatment of myasthenia gravis and as an antidote to nondepolarizing neuromuscular blocking agents.

pyridostigmine bromide

Mestinon, Mestinon-SR (CA), Mestinon Timespan, Regonol

Pharmacologic class: Anticholinesterase

Therapeutic class: Muscle stimulant, antimyasthenic

Pregnancy risk category C

Action

Prevents acetylcholine destruction, resulting in stronger contractions of muscles weakened by myasthenia gravis or curare-like neuromuscular blockers

Availability

Injection: 5 mg/ml

Syrup: 60 mg/5 ml

Tablets: 60 mg

Tablets (extended-release): 180 mg

Indications and dosages

Myasthenia gravis

Adults: 600 mg P.O. given over 24 hours, with doses spaced for maximum symptom relief. For myasthenic crisis, 2 mg or 1/30 of oral dose I.M. or very slow I.V. q 2 to 3 hours.

Postoperative reversal of nondepolarizing neuromuscular blockers

Adults: 10 to 20 mg slow I.V. injection (range is 0.1 to 0.25 mg/kg) with or immediately after 0.6 to 1.2 mg atropine sulfate I.V.

Dosage adjustment

• Renal impairment
• Seizure disorders

Off-label uses

• Myasthenia gravis in children
• Constipation in patients with Parkinson's disease
• Nerve agent prophylaxis

Contraindications

• Hypersensitivity to drug or bromides
• Mechanical intestinal or urinary tract obstruction

Precautions

Use cautiously in:
• seizure disorders, bronchial asthma, coronary occlusion, arrhythmias, bradycardia, hyperthyroidism, peptic ulcer, vagotonia, cholinergic crisis
• pregnant or breastfeeding patients
• children (safety and efficacy not established).

Administration

Don't exceed I.V. injection rate of 1 mg/minute.

Don't give concurrently with other anticholinesterase drugs.
• Have atropine available for use in emergencies.

Adverse reactions

CNS: headache, dysarthria, dysphoria, drowsiness, dizziness, headache, syncope, loss of consciousness, seizures

CV: decreased cardiac output leading to hypotension, bradycardia, nodal rhythm, atrioventricular block, cardiac arrest, arrhythmias

EENT: diplopia, lacrimation, miosis, spasm of accommodation, conjunctival hyperemia

GI: nausea, vomiting, diarrhea, abdominal cramps, increased peristalsis, flatulence dysphagia, increased salivation

GU: urinary frequency, urgency, or incontinence

Musculoskeletal: muscle weakness, fasciculations, and cramps; joint pain

Respiratory: increased pharyngeal and tracheobronchial secretions, dyspnea, central respiratory paralysis, respiratory muscle paralysis, laryngospasm, bronchospasm, bronchiolar constriction

Skin: diaphoresis, flushing, rash, urticaria

Other: thrombophlebitis at I.V. site, cholinergic crisis, anaphylaxis

Interactions

Drug-drug.Aminoglycosides: potentiation of neuromuscular blockade

Anesthetics (general and local), antiarrhythmics: decreased anticholinesterase effects

Atropine, belladonna derivatives: suppression of parasympathomimetic GI symptoms (leaving only fasciculations and voluntary muscle paralysis as signs of anticholinesterase overdose)

Corticosteroids: decreased anticholinesterase effects; after corticosteroid withdrawal, increased anticholinesterase effects

Ganglionic blockers (such as mecamy-lamine): increased anticholinesterase effects

Magnesium: antagonism of beneficial anticholinesterase effects

Nondepolarizing neuromuscular blockers (atropine, pancuronium, tubocurarine): antagonism of neuromuscular blockade and reversal of muscle relaxation after surgery (with parenteral pyridostigmine)

Other anticholinesterase drugs: in patients with myasthenia gravis, symptoms of anticholinesterase overdose that mimic underdose, causing patient's condition to worsen

Succinylcholine: increased and prolonged neuromuscular blockade (including respiratory depression)

Patient monitoring

• Assess patient's response to each dose.
• Monitor vital signs, ECG, and cardiovascular and respiratory status.

Assess for signs and symptoms of overdose, which indicate cholinergic crisis.

Patient teaching

• If patient is using syrup, advise him to pour it over ice.
• Instruct patient using extended-release tablets not to crush them.

Teach patient to recognize and promptly report signs and symptoms of overdose, including muscle fasciculations, sweating, excessive salivation, and constricted pupils.
• Tell patient drug may cause headache and muscle cramps. Encourage him to discuss activity recommendations and pain management with prescriber.
• Advise patient to monitor and report his response to ongoing therapy so that optimal dosage can be determined.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs mentioned above.

pyridostigmine

(peer-id-oh-stig-meen) ,

Mestinon

(trade name),

Mestinon SR

(trade name),

Mestinon Timespan

(trade name),

Regonol

(trade name)

Classification

Therapeutic: antimyasthenics
Pharmacologic: cholinergics
Pregnancy Category: C

Indications

Used to increase muscle strength in the symptomatic treatment of myasthenia gravis.Reversal of nondepolarizing neuromuscular blocking agents.Prophylaxis of lethal effects of poisoning with the nerve agent soman.

Action

Inhibits the breakdown of acetylcholine and prolongs its effects (anticholinesterase).
Effects include:
  • Miosis,
  • Increased intestinal and skeletal muscle tone,
  • Bronchial and ureteral constriction,
  • Bradycardia,
  • Increased salivation,
  • Lacrimation,
  • Sweating.

Therapeutic effects

Improved muscular function in patients with myasthenia gravis.
Reversal of paralysis from nondepolarizing neuromuscular blocking agents.
Prevention of Soman nerve gas toxicity.

Pharmacokinetics

Absorption: Poorly absorbed after oral administration, necessitating large oral doses compared with parenteral doses.
Distribution: Appears to cross the placenta.
Metabolism and Excretion: Metabolized by plasma cholinesterases and the liver.
Half-life: PO—3.7 hr; IV—1.9 hr.

Time/action profile (cholinergic effects)

ROUTEONSETPEAKDURATION
PO30–35 minunknown3–6 hr
PO-SR30–60 minunknown6–12 hr
IM15 minunknown2–4 hr
IV2–5 minunknown2–3 hr

Contraindications/Precautions

Contraindicated in: Hypersensitivity to pyridostigmine or bromides;Mechanical obstruction of the GI or GU tract;Known alcohol intolerance (syrup only).
Use Cautiously in: History of asthma;Ulcer disease;Cardiovascular disease;Epilepsy;Hyperthyroidism; Obstetric: May cause uterine irritability after IV administration near term; 20% of newborns display transient muscle weakness; Lactation / Pediatric: Safety not established.

Adverse Reactions/Side Effects

Central nervous system

  • seizures (life-threatening)
  • dizziness
  • weakness

Ear, Eye, Nose, Throat

  • lacrimation
  • miosis

Respiratory

  • bronchospasm (most frequent)
  • excessive secretions (most frequent)

Cardiovascular

  • bradycardia (most frequent)
  • hypotension

Gastrointestinal

  • abdominal cramps (most frequent)
  • diarrhea (most frequent)
  • excessive salivation (most frequent)
  • nausea (most frequent)
  • vomiting (most frequent)

Dermatologic

  • sweating (most frequent)
  • rashes

Interactions

Drug-Drug interaction

Cholinergic effects may be antagonized by other drugs possessing anticholinergic properties, including antihistamines, antidepressants, atropine, haloperidol, phenothiazines, procainamide, quinidine, or disopyramide.Prolongs the action of depolarizing muscle-relaxing agents and cholinesterase inhibitors (succinylcholine, decamethonium ).↑ toxicity with other cholinesterase inhibitors, including echothiophate.

Route/Dosage

Myasthenia Gravis
Oral (Adults) Tablets/syrup—30–60 mg q 3–4 hr initially; then adjusted as required; usual maintenance dose is 600 mg/day in divided doses (range 60–1500 mg/day). Extended-release tablets—180–540 mg 1–2 times daily (dosing interval should be at least 6 hr; may be associated with increased risk of cholinergic crisis; concurrent immediate-release products may be required).
Oral (Children) 7 mg/kg (200 mg/m2)/day in 5–6 divided doses.
Intramuscular Intravenous (Adults) 2 mg (1/30 of oral dose); may be repeated q 2–3 hr. During labor/delivery—1 mg before second stage of labor is complete.
Intramuscular (Neonates Born to Myasthenic Mothers) 50–150 mcg/kg q 4–6 hr.
Antidote for Nondepolarizing Neuromuscular Blocking Agents
Intravenous (Adults) 10–20 mg; pretreat with 0.6–1.2 mg atropine IV.

Prevention of Soman Nerve Gas Effects

Oral (Adults) 30 mg every 8 hr before exposure, stopped on exposure to gas.

Availability (generic available)

Tablets: 60 mg
Extended-release tablets: 180 mg
Syrup: 60 mg/5 mL
Injection: 5 mg/mL

Nursing implications

Nursing assessment

  • Assess pulse, respiratory rate, and BP before administration. Report significant changes in heart rate.
  • Myasthenia Gravis: Assess neuromuscular status, including vital capacity, ptosis, diplopia, chewing, swallowing, hand grasp, and gait before administering and at peak effect. Patients with myasthenia gravis may be advised to keep a daily record of their condition and the effects of this medication.
    • Assess patient for overdose, underdose, or resistance. Both have similar symptoms (muscle weakness, dyspnea, dysphagia), but symptoms of overdosage usually occur within 1 hr of administration, whereas symptoms of underdose occur ≥3 hr after administration. Overdose (cholinergic crisis) symptoms may also include increased respiratory secretions and saliva, bradycardia, nausea, vomiting, cramping, diarrhea, and diaphoresis. A Tensilon test (edrophonium chloride) may be used to differentiate between overdosage and underdosage.
  • Antidote to Nondepolarizing Neuromuscular Blocking Agents: Monitor reversal of effect of neuromuscular blocking agents with a peripheral nerve stimulator. Recovery usually occurs consecutively in the following muscles: diaphragm, intercostal muscles, muscles of the glottis, abdominal muscles, limb muscles, muscles of mastication, and levator muscles of eyelids. Closely observe patient for residual muscle weakness and respiratory distress throughout the recovery period. Maintain airway patency and ventilation until recovery of normal respirations occurs.
  • Atropine is the antidote.

Potential Nursing Diagnoses

Impaired physical mobility (Indications)
Ineffective breathing pattern (Indications)

Implementation

  • For patients who have difficulty chewing, pyridostigmine may be administered 30 min before meals.
    • Oral dose is not interchangeable with IV dose. Parenteral form is 30 times more potent.
    • When used as an antidote to nondepolarizing neuromuscular blocking agents, atropine may be ordered before or currently with large doses of pyridostigmine to prevent or to treat bradycardia and other side effects.
  • Oral: Administer with food or milk to minimize side effects. Extended-release tablets should be swallowed whole; do not crush, break, or chew. Regular tablets or syrup may be administered with extended-release tablets for optimum control of symptoms. Mottled appearance of sustained-release tablet does not affect potency.
  • Intravenous Administration
  • pH: 6.0–7.0.
  • Administer undiluted. Do not add to IV solutions. May be given through Y-site of infusion of D5W, 0.9% NaCl, LR, D5/Ringer’s solution, or D5/LR. Concentration: 5 mg/mL.
  • Rate: For myasthenia gravis, administer each 0.5 mg over 1 min. For reversal of nondepolarizing neuromuscular blocking agents, administer each 5 mg over 1 min.
  • Syringe Compatibility: glycopyrrolate
  • Y-Site Compatibility: heparin, hydrocortisone sodium succinate, potassium chloride, vitamin B complex with C

Patient/Family Teaching

  • Instruct patient to take medication as directed. Do not skip or double up on missed doses. Patients with a history of dysphagia should have a nonelectric or battery-operated back-up alarm clock to remind them of exact dose time. Patients with dysphagia may not be able to swallow medication if the dose is not taken exactly on time. Taking dose late may result in myasthenic crisis. Taking dose early may result in cholinergic crisis. Patients with myasthenia gravis must continue this regimen as a life-long therapy.
  • Advise patient to carry identification describing disease and medication regimen at all times.
  • Instruct patient to space activities to avoid fatigue.

Evaluation/Desired Outcomes

  • Relief of ptosis and diplopia; improved chewing, swallowing, extremity strength, and breathing without the appearance of cholinergic symptoms.
  • Reversal of nondepolarizing neuromuscular blocking agents in general anesthesia.
  • Prevention of Soman nerve gas toxicity.

Regonol,

trademark for an anticholinesterase drug inaccurate (pyridostigmine), used as an adjunct to anesthesia.
References in periodicals archive ?
Regonol is indicated as a reversal agent or antagonist to the neuromuscular blocking effects of nondepolarizing muscle relaxants.
Regonol is one of four generic injectables recently launched by SAB-Pharma marking the company's introduction to the U.