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Acute exposure to cholinesterase inhibitors can cause a cholinergic crisis characterized by severe nausea/vomiting, salivation, sweating, bradycardia, hypotension, collapse, and convulsions. Increasing muscle weakness is a possibility and may result in death if respiratory muscles are involved. Accumulation of ACh at motor nerves causes overstimulation of nicotinic expression at the neuromuscular junction. When this occurs symptoms such as muscle weakness, fatigue, muscle cramps, fasciculation, and paralysis can be seen. When there is an accumulation of ACh at autonomic ganglia this causes overstimulation of nicotinic expression in the sympathetic system. Symptoms associated with this are hypertension, and hypoglycemia. Overstimulation of nicotinic acetylcholine receptors in the central nervous system, due to accumulation of ACh, results in anxiety, headache, convulsions, ataxia, depression of respiration and circulation, tremor, general weakness, and potentially coma. When there is expression of muscarinic overstimulation due to excess acetylcholine at muscarinic acetylcholine receptors symptoms of visual disturbances, tightness in chest, wheezing due to bronchoconstriction, increased bronchial secretions, increased salivation, lacrimation, sweating, peristalsis, and urination can occur. Certain reproductive effects in fertility, growth, and development for males and females have been linked specifically to organophosphate pesticide exposure. Most of the research on reproductive effects has been conducted on farmers working with pesticides and insecticdes in rural areas. In females menstrual cycle disturbances, longer pregnancies, spontaneous abortions, stillbirths, and some developmental effects in offspring have been linked to organophosphate pesticide exposure. Prenatal exposure has been linked to impaired fetal growth and development. Neurotoxic effects have also been linked to poisoning with OP pesticides causing four neurotoxic effects in humans: cholinergic syndrome, intermediate syndrome, organophosphate-induced delayed polyneuropathy (OPIDP), and chronic organophosphate-induced neuropsychiatric disorder (COPIND). These syndromes result after acute and chronic exposure to OP pesticides.

Pyridostigmine is a cholinesterase or acetylcholinesterase (AChE) inhibitor. A cholinesterase inhibitor (or 'anticholinesterase') suppresses the action of acetylcholinesterase. Because of its essential function, chemicals that interfere with the action of acetylcholinesterase are potent neurotoxins, causing excessive salivation and eye-watering in low doses, followed by muscle spasms and ultimately death. Nerve gases and many substances used in insecticides have been shown to act by binding a serine in the active site of acetylcholine esterase, inhibiting the enzyme completely. Acetylcholine esterase breaks down the neurotransmitter acetylcholine, which is released at nerve and muscle junctions, in order to allow the muscle or organ to relax. The result of acetylcholine esterase inhibition is that acetylcholine builds up and continues to act so that any nerve impulses are continually transmitted and muscle contractions do not stop. Among the most common acetylcholinesterase inhibitors are phosphorus-based compounds, which are designed to bind to the active site of the enzyme. The structural requirements are a phosphorus atom bearing two lipophilic groups, a leaving group (such as a halide or thiocyanate), and a terminal oxygen.

Symptoms of low dose exposure include excessive salivation and eye-watering. Acute dose symptoms include severe nausea/vomiting, salivation, sweating, bradycardia, hypotension, collapse, and convulsions. Increasing muscle weakness is a possibility and may result in death if respiratory muscles are involved. Hypertension, hypoglycemia, anxiety, headache, tremor and ataxia may also result.

EFFECTS...ON CENTRAL NERVOUS SYSTEM ARE...CHARACTERIZED BY STIMULATION OR FACILITATION AT VARIOUS SITES, SUCCEEDED BY INHIBITION OR PARALYSIS AT HIGHER CONCN. ... RESPIRATORY & OTHER SUBCORTICAL CENTERS LIKEWISE SHOW STIMULATION AFTER LOW DOSES AND DEPRESSION WITH HIGHER OR TOXIC DOSES. /ANTI-CHOLINESTERASE AGENTS/

GI SYMPTOMS OCCUR EARLIEST AFTER INGESTION, & INCL ANOREXIA, NAUSEA & VOMITING, ABDOMINAL CRAMPS, & DIARRHEA. WITH PERCUTANEOUS ABSORPTION OF LIQ, LOCALIZED SWEATING & MUSCULAR FASCICULATION IN IMMEDIATE VICINITY ARE GENERALLY EARLIEST MANIFESTATIONS. /ANTI-CHOLINESTERASE AGENTS/

...EFFECTS ON CNS INCL CONFUSION, ATAXIA, SLURRED SPEECH, LOSS OF REFLEXES, CHEYNE-STOKES RESP, GENERALIZED CONVULSIONS, COMA, & CENTRAL RESP PARALYSIS. ... TIME OF DEATH AFTER SINGLE ACUTE EXPOSURE MAY RANGE FROM LESS THAN 5 MIN TO NEARLY 24 HR, DEPENDING UPON DOSE, ROUTE, AGENT... CAUSE OF DEATH IS PRIMARILY RESPIRATORY FAILURE USUALLY ACCOMPANIED BY A SECONDARY CARDIOVASCULAR COMPONENT. /ANTI-CHOLINESTERASE AGENTS/

NICOTINIC ACTIONS @ NEUROMUSCULAR JUNCTIONS OF SKELETAL MUSCLE...FATIGABILITY & GENERALIZED WEAKNESS, INVOLUNTARY TWITCHINGS...SEVERE WEAKNESS & PARALYSIS; UNDOUBTABLY A CENTRAL COMPONENT OF ACTION CONTRIBUTES TO SOME OF THESE EFFECTS. THE MOST SERIOUS CONSEQUENCE...IS PARALYSIS OF RESPIRATORY MUSCLES. /ANTI-CHOLINESTERASE AGENTS/

For more Human Toxicity Excerpts (Complete) data for PYRIDOSTIGMINE BROMIDE (7 total), please visit the HSDB record page.

Drug Induced Liver Injury Rank (DILIrank 2.0)

Pyridostigmine bromide

vLess-DILI-concern

0

No match

DOI:10.1016/j.drudis.2016.02.015

1) ESTABLISH CLEAR AIRWAY & TISSUE OXYGENATION BY ASPIRATION OF SECRETIONS & IF NECESSARY, BY ASSISTED PULMONARY VENTILATION WITH OXYGEN. IMPROVE TISSUE OXYGENATION AS MUCH AS POSSIBLE BEFORE ADMINISTERING ATROPINE TO MINIMIZE THE RISK OF VENTRICULAR FIBRILLATION. /CARBAMATES, CHOLINESTERASE INHIBITORS/

2) ADMIN ATROPINE SULFATE IV, OR IM IF IV INJECTION IS NOT POSSIBLE... IN MODERATELY SEVERE POISONING: ADULT DOSAGE, INCLUDING CHILDREN OVER 12 YR: 0.4-2.0 MG REPEATED EVERY 15 MIN UNTIL ATROPINIZATION IS ACHIEVED (TACHYCARDIA, FLUSHING, DRY MOUTH, MYDRIASIS). MAINTAIN ATROPINIZATION BY REPEATED DOSES FOR 2-12 HR, OR LONGER, DEPENDING ON SEVERITY OF POISONING... DOSAGE FOR CHILDREN UNDER 12 YEARS: 0.05 MG/KG BODY WT REPEATED EVERY 15 MIN UNTIL ATROPINIZATION IS ACHIEVED. MAINTAIN ATROPINIZATION WITH REPEATED DOSAGE OF 0.02-0.05 MG/KG. SEVERELY POISONED INDIVIDUALS MAY EXHIBIT REMARKABLE TOLERANCE TO ATROPINE; TWICE THE DOSES SUGGESTED ABOVE MAY BE NEEDED... /CARBAMATES, CHOLINESTERASE INHIBITORS/

3. PRALIDOXIME (PROTOPAM-AYERST, 2-PAM) IS OF DOUBTFUL VALUE IN POISONINGS BY CARBAMATE INHIBITORS OF CHOLINESTERASE. ATROPINE ALONE IS ALMOST ALWAYS AN ADEQUATE ANTIDOTE. PRALIDOXIME IS PROBABLY CONTRAINDICATED IN POISONINGS BY CARBARYL, SPECIFICALLY. IF VICTIM OF CARBAMATE POISONING EXHIBITS SEVERE MUSCLE WEAKNESS &/OR RESPIRATORY DEPRESSION, OR IF POISONING INVOLVES A COMBINATION OF CARBAMATE & ORGANOPHOSPHATE, A DILUTE SOLUTION OF PRALIDOXIME (TOTAL DOSE IN 250 ML 5% GLUCOSE SOLN) MAY BE GIVEN CAUTIOUSLY IV. THE INFUSION SHOULD BE TERMINATED IF PATIENT'S CONDITION WORSENS. PRALIDOXIME DOSAGE: ADULTS, 1.0 G; FOR CHILDREN UNDER 12 YR, 20-50 MG/KG. 4. OBSERVE TREATED PATIENTS CLOSELY AT LEAST 24 HR TO INSURE THAT SYMPTOMS (POSSIBLY PULMONARY EDEMA) DO NOT RECUR AS ATROPINIZATION WEARS OFF. IN VERY SEVERE POISONINGS, METABOLIC DISPOSITION OF TOXICANT MAY REQUIRE SEVERAL HR OR DAYS DURING WHICH ATROPINIZATION MUST BE MAINTAINED. /CARBAMATES, CHOLINESTERASE INHIBITORS/

6. IF...INGESTED IN QUANTITY SUFFICIENT TO CAUSE POISONING, EMPTY THE STOMACH & INTESTINE. A. IF VICTIM IS ALERT & RESPIRATION IS NOT DEPRESSED, GIVE SYRUP OF IPECAC, FOLLOWED BY 1-2 GLASSES OF WATER TO INDUCE VOMITING; ADULTS (INCLUDING CHILDREN OVER 12), 30 ML; CHILDREN (UNDER 12 YR), 15 ML. CAUTION: OBSERVE VICTIM CLOSELY AFTER ADMIN IPECAC, IF CONSCIOUSNESS LEVEL DECLINES, OR IF VOMITING HAS NOT OCCURRED IN 15 MIN, PROCEED IMMEDIATELY TO INTUBATE THE STOMACH. FOLLOWING EMESIS, HAVE VICTIM DRINK A SUSPENSION OF /PRC: 30 G ACTIVATED CHARCOAL IN 3-4 OZ OF WATER (CHILDREN), 100 G IN 8-10 OZ OF WATER (ADULTS)/...TO BIND TOXICANT REMAINING IN THE GI TRACT. /CARBAMATES, CHOLINESTERASE INHIBITORS/

For more Antidote and Emergency Treatment (Complete) data for PYRIDOSTIGMINE BROMIDE (6 total), please visit the HSDB record page.

ITS ONSET OF ACTION BY ORAL ROUTE IS ABOUT 320 MIN...ITS DURATION OF ACTION BY THE ORAL ROUTE IS USUALLY SOMEWHAT LONGER AND ABSORPTION IS LESS ERRATIC THAN NEOSTIGMINE, WHICH ARE ADVANTAGES.

Plasma concn of pyridostigmine was determined in 2 nursing mothers who were receiving oral doses of pyridostigmine bromide, 120-300 mg daily. The drug was not detectable in infant plasma and there were no signs of drug effects in the infant.