Guanidine

Myasthenic Agents, Other

atrial fibrillation / Early / 0-1.0
interstitial nephritis / Delayed / 0-1.0
renal tubular necrosis / Delayed / 0-1.0

confusion / Early / 1.0-10.0
leukopenia / Delayed / 1.0-10.0
anemia / Delayed / 1.0-10.0
thrombocytopenia / Delayed / 1.0-10.0
gastritis / Delayed / 1.0-10.0
palpitations / Early / 1.0-10.0
sinus tachycardia / Rapid / 1.0-10.0
hypotension / Rapid / 1.0-10.0
ataxia / Delayed / 0-1.0
hallucinations / Early / 0-1.0
psychosis / Early / 0-1.0
elevated hepatic enzymes / Delayed / 0-1.0

irritability / Delayed / 1.0-10.0
emotional lability / Early / 1.0-10.0
tremor / Early / 1.0-10.0
paresthesias / Delayed / 1.0-10.0
restlessness / Early / 1.0-10.0
anxiety / Delayed / 1.0-10.0
anorexia / Delayed / 1.0-10.0
rash / Early / 1.0-10.0
folliculitis / Delayed / 1.0-10.0
purpura / Delayed / 0-1.0
ecchymosis / Delayed / 0-1.0
petechiae / Delayed / 0-1.0
diarrhea / Early / 10.0
xerostomia / Early / 10.0
nausea / Early / 10.0
hyperhidrosis / Delayed / 10.0
flushing / Rapid / 10.0
xerosis / Delayed / 10.0
pharyngitis / Delayed / Incidence not known
fever / Early / Incidence not known

Guanidine

Rx

Oral cholinergic muscle stimulant
Used in adults for the myasthenic syndrome of Easton-Lambert; not indicated for myasthenia gravis
Gastrointestinal adverse events (e.g., nausea, diarrhea, abdominal cramping) may preclude use in some patients

Initially, 10 to 15 mg/kg/day PO given in 3 or 4 divided doses. Increase gradually to 35 mg/kg/day PO in 3 or 4 divided doses, or up to the development of side effects; patient tolerance is highly variable. Continued therapy based on tolerable dose. Removal of the primary neoplastic lesion may result in improvement of symptoms, resulting in termination of therapy. Guanidine is not indicated for the treatment of myasthenia gravis.

Specific guidelines for dosage adjustments in hepatic impairment are not available; caution is recommended.

Specific guidelines for dosage adjustments in renal impairment are not available; it appears that no dosage adjustments are needed.

Ambenonium Chloride: (Major) Cholinergic agonists can cause additive pharmacodynamic effects if used concomitantly with cholinesterase inhibitors. Concurrent use is unlikely to be tolerated by the patient and should be avoided.
Amoxapine: (Major) Amoxapine may antagonize some of the effects of parasympathomimetics. However, bethanechol has occasionally been used therapeutically to offset some of the adverse antimuscarinic effects of cyclic antidepressants. Due to their anticholinergic actions, some cyclic antidepressants, such as amoxapine, may potentially antagonize the therapeutic actions of cholinergic agonists.
Anticholinergics: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Atropine: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Atropine; Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Atropine; Difenoxin: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Atropine; Edrophonium: (Major) Cholinergic agonists can cause additive pharmacodynamic effects if used concomitantly with cholinesterase inhibitors. Concurrent use is unlikely to be tolerated by the patient and should be avoided. (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Belladonna; Opium: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Benztropine: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Bethanechol: (Moderate) Guanidine and bethanechol are both cholinergic agonists. Coadministration is expected to result in additive parasympathomimetic effects.
Budesonide; Glycopyrrolate; Formoterol: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Carbamazepine: (Minor) Bone marrow suppression is associated with guanidine therapy. Avoid concomitant use of other drugs known to cause bone marrow suppression such as carbamazepine.
Cevimeline: (Moderate) Cevimeline and guanidine are both cholinergic agonists. Coadministration is expected to result in additive parasympathomimetic effects.
Chlordiazepoxide; Clidinium: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Chlorpromazine: (Minor) Bone marrow suppression is associated with guanidine therapy. Avoid concomitant use of other drugs known to cause bone marrow suppression such as phenothiazines.
Cholinesterase inhibitors: (Major) Cholinergic agonists can cause additive pharmacodynamic effects if used concomitantly with cholinesterase inhibitors. Concurrent use is unlikely to be tolerated by the patient and should be avoided.
Clozapine: (Minor) Bone marrow suppression is associated with guanidine therapy. Avoid concomitant use of other drugs known to cause bone marrow suppression such as clozapine.
Codeine; Phenylephrine; Promethazine: (Minor) Bone marrow suppression is associated with guanidine therapy. Avoid concomitant use of other drugs known to cause bone marrow suppression such as phenothiazines.
Codeine; Promethazine: (Minor) Bone marrow suppression is associated with guanidine therapy. Avoid concomitant use of other drugs known to cause bone marrow suppression such as phenothiazines.
Dicyclomine: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Diphenoxylate; Atropine: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Disopyramide: (Moderate) Disopyramide possesses clinically significant antimuscarinic properties and these appear to be dose-related. It is possible that disopyramide could antagonize the muscarinic actions of cholinergic agonists. Clinicians should be alert to this possibility.
Donepezil: (Major) Cholinergic agonists can cause additive pharmacodynamic effects if used concomitantly with cholinesterase inhibitors. Concurrent use is unlikely to be tolerated by the patient and should be avoided.
Donepezil; Memantine: (Major) Cholinergic agonists can cause additive pharmacodynamic effects if used concomitantly with cholinesterase inhibitors. Concurrent use is unlikely to be tolerated by the patient and should be avoided.
Edrophonium: (Major) Cholinergic agonists can cause additive pharmacodynamic effects if used concomitantly with cholinesterase inhibitors. Concurrent use is unlikely to be tolerated by the patient and should be avoided.
Felbamate: (Minor) Bone marrow suppression is associated with guanidine therapy. Avoid concomitant use of other drugs known to cause bone marrow suppression such as felbamate.
Flavoxate: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Fluphenazine: (Minor) Bone marrow suppression is associated with guanidine therapy. Avoid concomitant use of other drugs known to cause bone marrow suppression such as phenothiazines.
Galantamine: (Major) Cholinergic agonists can cause additive pharmacodynamic effects if used concomitantly with cholinesterase inhibitors. Concurrent use is unlikely to be tolerated by the patient and should be avoided.
Glycopyrrolate: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Glycopyrrolate; Formoterol: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Homatropine; Hydrocodone: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Hyoscyamine: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate; Sodium Biphosphate: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Indacaterol; Glycopyrrolate: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Maprotiline: (Major) Maprotiline may antagonize some of the effects of parasympathomimetics. However, bethanechol has occasionally been used therapeutically to offset some of the adverse antimuscarinic effects of cyclic antidepressants. Due to their anticholinergic actions, some cyclic antidepressants like maprotiline may potentially antagonize the therapeutic actions of the cholinesterase-inhibitors used for the treatment of dementia.
Meperidine; Promethazine: (Minor) Bone marrow suppression is associated with guanidine therapy. Avoid concomitant use of other drugs known to cause bone marrow suppression such as phenothiazines.
Methenamine; Sodium Acid Phosphate; Methylene Blue; Hyoscyamine: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Methscopolamine: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Neostigmine: (Major) Cholinergic agonists can cause additive pharmacodynamic effects if used concomitantly with cholinesterase inhibitors. Concurrent use is unlikely to be tolerated by the patient and should be avoided.
Oxybutynin: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Perphenazine: (Minor) Bone marrow suppression is associated with guanidine therapy. Avoid concomitant use of other drugs known to cause bone marrow suppression such as phenothiazines.
Perphenazine; Amitriptyline: (Minor) Bone marrow suppression is associated with guanidine therapy. Avoid concomitant use of other drugs known to cause bone marrow suppression such as phenothiazines.
Phenobarbital; Hyoscyamine; Atropine; Scopolamine: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Phenothiazines: (Minor) Bone marrow suppression is associated with guanidine therapy. Avoid concomitant use of other drugs known to cause bone marrow suppression such as phenothiazines.
Physostigmine: (Major) Cholinergic agonists can cause additive pharmacodynamic effects if used concomitantly with cholinesterase inhibitors. Concurrent use is unlikely to be tolerated by the patient and should be avoided.
Pilocarpine: (Moderate) Guanidine and pilocarpine are both cholinergic agonists. Coadministration is expected to result in additive parasympathomimetic effects.
Pralidoxime: (Moderate) Guanidine and pralidoxime are both cholinergic agonists. Coadministration is expected to result in additive parasympathomimetic effects.
Prochlorperazine: (Minor) Bone marrow suppression is associated with guanidine therapy. Avoid concomitant use of other drugs known to cause bone marrow suppression such as phenothiazines.
Promethazine: (Minor) Bone marrow suppression is associated with guanidine therapy. Avoid concomitant use of other drugs known to cause bone marrow suppression such as phenothiazines.
Promethazine; Dextromethorphan: (Minor) Bone marrow suppression is associated with guanidine therapy. Avoid concomitant use of other drugs known to cause bone marrow suppression such as phenothiazines.
Promethazine; Phenylephrine: (Minor) Bone marrow suppression is associated with guanidine therapy. Avoid concomitant use of other drugs known to cause bone marrow suppression such as phenothiazines.
Propantheline: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Pyridostigmine: (Major) Cholinergic agonists can cause additive pharmacodynamic effects if used concomitantly with cholinesterase inhibitors. Concurrent use is unlikely to be tolerated by the patient and should be avoided.
Rivastigmine: (Major) Cholinergic agonists can cause additive pharmacodynamic effects if used concomitantly with cholinesterase inhibitors. Concurrent use is unlikely to be tolerated by the patient and should be avoided.
Scopolamine: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Sulfinpyrazone: (Minor) Bone marrow suppression is associated with guanidine therapy. Avoid concomitant use of other drugs known to cause bone marrow suppression such as sulfinpyrazone.
Tacrine: (Major) Cholinergic agonists can cause additive pharmacodynamic effects if used concomitantly with cholinesterase inhibitors. Concurrent use is unlikely to be tolerated by the patient and should be avoided.
Thiethylperazine: (Minor) Bone marrow suppression is associated with guanidine therapy. Avoid concomitant use of other drugs known to cause bone marrow suppression such as phenothiazines.
Thioridazine: (Minor) Bone marrow suppression is associated with guanidine therapy. Avoid concomitant use of other drugs known to cause bone marrow suppression such as phenothiazines.
Tricyclic antidepressants: (Moderate) Tricyclic antidepressants (TCAs) may antagonize some of the effects of parasympathomimetics (e.g., cholinesterase inhibitors) due to their anticholinergic activity. However, parasympathomimetics like bethanechol have occasionally been used historically to offset some of the adverse peripheral antimuscarinic (anticholinergic) effects of TCAs, such as dry mouth, constipation, or urinary retention. For years, physostigmine was used as an adjunct to the treatment of TCA overdose; however, its efficacy was limited to addressing anticholinergic effects. Additionally, case reports suggest that harmful effects such as seizures and bradyarrhythmias progressing to asystole, especially in patients with cardiac conduction abnormalities at baseline, are possible. For these reasons, physostigmine is no longer considered a standard of care in the treatment of TCA overdose.
Trifluoperazine: (Minor) Bone marrow suppression is associated with guanidine therapy. Avoid concomitant use of other drugs known to cause bone marrow suppression such as phenothiazines.
Trihexyphenidyl: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
Trospium: (Moderate) Pharmacologically, parasympathomimetic drugs enhance muscarinic/cholinergic function. Because trospium is an antimuscarinic, the muscarinic actions of drugs known as parasympathomimetics, including direct cholinergic agonists, could be antagonized when used concomitantly with trospium.

Guanidine Oral Tab: 125mg

35 mg/kg/day PO.

35 mg/kg/day PO.

Safety and efficacy have not been established.

Safety and efficacy have not been established.

Safety and efficacy have not been established.

Guanidine is indicated to reduce the symptoms of the myasthenic syndrome of Lambert-Eaton, including muscle weakness and easy fatigability. Guanidine appears to enhance the release of acetylcholine following a nerve impulse and slows the rate of depolarization and repolarization of muscle cell membranes.

No pharmacokinetic information is available from the manufacturer at this time.

No pharmacokinetic information is available from the manufacturer.

According to the manufacturer, the safe use of guanidine during pregnancy has not been established, and the benefits of guanidine therapy should be weighed against any potential harm to the fetus when considering use of the drug during pregnancy. No FDA pregnancy risk category is assigned in the product literature. Due to a lack of data assessing fetal risk, and the potential for hematologic, neurologic, and cardiac toxicity associated with the drug, guanidine should be used during pregnancy only if clearly needed. The effects of guanidine in labor and delivery are unknown.

According to the manufacturer, guanidine is excreted in breast milk and breast-feeding should be discontinued during treatment. Due to a lack of data evaluating safety in the nursing infant, and the potential for hematologic, neurologic, and cardiac toxicity associated with the drug, breast-feeding should be avoided if guanidine therapy is necessary in the postpartum mother. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally ingested drug, healthcare providers are encouraged to report the adverse effect to the FDA.