Updated: 4/1/2018

Muscarinic Antagonists

Review Topic
Therapeutic Actions for Muscarinic Antagonists

Organ System
Application and Comments
Atropine, homatropine, tropicamide

Eye and Cardiac

• Causes mydriasis and cycloplegia
• Used for ophthalmologic exams
• Can be used for post-MI bradyarrythmias 
Benztropine  CNS • Parkinson's disease
Scopolamine  CNS • Motion sickness
• Fast onset
Ipratropium  Respiratory • Asthma
• Tiotropium produces a longer bronchodilator effect
• Relief of rhinorrhea with common cold, allergic and nonallergic rhinitis
Oxybutynin, trospium, glycopyrrolate Genitourinary • Reduce urgency in mild cystitis
• Reduce bladder spasms after urologic surgery
Methscopolamine, pirenzepine, propantheline Gastrointestinal • Peptic ulcer treatment


  • Muscarinic antagonist
    • blocks effects of cholinesterase inhibitor poisoning
  • Organ system
    • eye: ↑ pupil dilation and cycloplegia
    • lungs: ↓ secretions
    • GI and GU: ↓ stomach acid secretion, ↓ gut motility, and ↓ urgency in cystitis
  • Toxicity
    • CNS: ↑ body temperature, disorientation, hyperthermia in infants
    • Cardiovascular: tachycardia and flushing
    • Dermatologic: anhidrosis and urticaria
    • GI and GU: dry mouth, constipation, urinary retention 
    • Ocular: cycloplegia, acute angle-closure glaucoma, dry eyes
  • The atropine adage: "hot as a hare, dry as a bone, red as a beet, blind as a bat, mad as a hatter, the bowel and bladder loser their tone, and the heart runs alone" 

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Questions (5)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2

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(M1.PH.75) A 29-year-old farm hand is brought into the emergency department by his friends because he passed out while working in the field and was not able to be aroused. His friends state they thought he had a stomach bug as he was sweating profusely and had diarrhea and vomiting prior to losing consciousness. On exam, the patient's vitals are: T: 36 deg C, HR: 60 bpm, BP: 100/60 mmHg, RR: 12, SaO2: 99%. Diaphoresis, lacrimation, and increased salivation are appreciated. The patient's eyes are shown in Figure A. Which of the following medications should be administered to this patient? Review Topic

QID: 106850

Pyridostigmine only




Atropine only




Pyridostigmine and Physostigmine




Atropine and Pralidoxime




Sodium Bicarbonate and Pralidoxime




Select Answer to see Preferred Response


(M1.PH.44) A 5-year-old boy is brought to the ED with fever and altered mental status. The boy was in his normal state of health until a few hours ago when he began to "not feel good" while on a deep-sea fishing trip as part of his family vacation. By the time that the family made it back to shore, the boy was experiencing blurred vision and confusion. In the ED his vitals were 101.6F, HR160, RR18, and O2 99% on room air. On exam, his skin is dry and flushed, and his abdomen is covered in small, round, stickers similar to that in Figure A. What gastrointestinal and urinary symptoms would you expect in this patient? Review Topic

QID: 101708

Incontinence of stool; urine retention




Incontinence of stool and urine




Constipation; urine retention




Constipation; incontinence of urine




Incontinence of stool; no urinary symptoms




Select Answer to see Preferred Response

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