Psychiatric Drugs and Medications Q 16

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Cholinergics are contraindicated in:

  

     A. Tachycardia

     B. Hypothyroidism

     C. Hypotension

     D. Asthma

    

    

Correct Answer: D. Asthma

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Bronchial asthma is a contraindication of cholinergic because the administration of cholinergic will cause bronchoconstriction. Bronchial muscles constrict, precipitating an attack of bronchial asthma. Mortality from acute poisoning generally results from respiratory failure due to a combination of neuromuscular weakness, depression of the CNS respiratory center, bronchoconstriction, and excessive respiratory secretions.

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Option A: Cholinergic medications can cause muscarinic and/or nicotinic adverse effects. Acetylcholine hyperpolarizes the SA nodal cells through M2 receptors of the heart. As a result, bradycardia or even cardiac arrest may occur. At the A-V node and Purkinje fibers, conduction slows, and a complete A-V block may occur. Due to non-uniform vagal innervation of atrial fibers, people may have a predisposition to atrial fibrillation or flutter.

Option B: Anticholinesterases have medical use for the treatment of myasthenia gravis, reversal of neuromuscular blockade, Alzheimer’s disease. The initial first-line therapy for most patients is anticholinesterase medication, usually pyridostigmine. Neostigmine is also available but not commonly used.

Option C: M3 receptors present on the blood vessels mediated dilation, causing a fall in blood pressure and flushing. The peripheral nervous system consists of the autonomic and the somatic nervous system. The autonomic nervous system can be further broken down into sympathetic and parasympathetic nervous systems. The parasympathetic nervous system regulates various organ and gland functions and primarily uses acetylcholine as its primary neurotransmitter, as do all the cholinomimetics.

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