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Pharmacology > Cholinomimetic drugs > Flashcards

Cholinomimetic drugs Flashcards

1
Q

What are cholinomimetic drugs?

A

They are drugs which directly or indirectly stimulate cholinoreceptors

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2
Q

What are the different types of cholinomimetic drugs?

A
  1. Universal
  2. M
  3. N
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3
Q

What are the Universal cholinomimetic drugs?

A

Acetylcholine and carbachol

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4
Q

What are the M cholinomimetic drugs?

A
  • Pilocarpine
  • Bethanechol
  • Cevimeline
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5
Q

What are the N cholinomimetic drugs?

A

Nicotine and lobeline

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6
Q

What are the pharmacodynamics of acetyl chloride?

A
  1. It has a strong but short action because of its fast in vivo metabolism by acetylcholinesterase enzyme
  2. its effects are dose dependent
  3. in low doses it affects M receptors only
  4. in high doses it stimulates both M and N receptors
  5. action on N receptors is only notable in case of the blockage of M receptors
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7
Q

What are the local pharmacological actions of acetylcholine?

A

Myosis and accommodation spasm after using eye drops

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8
Q

What are the systemic pharmacological actions of acetylcholine?

A
  1. Generalized vasodilation leading to fall and blood pressure buy extra synaptic M3 receptors
  2. bradycardia by stimulating M2 receptors at which there is a decrease in frequency of spontaneous diastolic depolarization of SA anode
  3. decrease in force of contractility of Atria and AV conductivity by M2 receptors
  4. Insignificant decrease in force of contractility of ventricles
  5. Bronchospasm and activation of tracheobronchial glands
  6. increase in the secretion of stomach and intestine by stimulation of M3 receptors
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9
Q

What are the clinical usages of acetylcholine?

A

Prevention of increase in intraocular pressure during surgical interventions and cases of cataracts and keratoplasty

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10
Q

What is the difference between carbachol and acetylcholine when it comes to their action?

A
  • In contrast to acetylcholine it is stable towards acetylcholinesterase enzyme and exerts longer but poor action.
  • It has higher affinity toward N receptors which are mostly located on autonomic ganglions
  • Its pharmacological effects are similar to those of acetylcholine chloridum
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11
Q

What are the differences between the M type cholinomimetics?

A
  • Pilocarpine is a natural alkaloid obtained by plants, bethanechol and cevimeline have a synthetic origin.
  • Pilocarpine has both local and resorptive action, bethanechol and cevimeline have systemic effects.
  • Cevimeline has more affinity towards M1 and M3 receptors
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12
Q

what are the local effects pilocarpine on the eyes?

A
  1. Miosis
  2. Reduction of intraocular pressure
  3. spasm of accommodation
  4. micropsia
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13
Q

what are the resorptive or systemic effects of M cholinomimetics?

A
  1. Bradycardia
  2. stimulation of M3 receptors
    - pilocarpine activates exocrine, sweat, and salivary glands
    - bethanechol acts towards smooth muscles of urinary and GIT
    - Cevimeline acts on salivary and lacrimal glands
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14
Q

what is the clinical use of Cevimeline?

A

It is used in the treatment of Sjorgen syndrome which includes xerostomia and xerophthalmia. In contrast to pilocarpine it has longer effect and less side effects.

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14
Q

what is the clinical use of pilocarpine?

A

It is used in the complex treatment of open angle glaucoma and eye drops

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15
Q

What is the clinical use of bethanechol?

A
  • It is used in case of post surgical Constipation, paralytic ileus, and diabetic neuropathy for treating insufficient dumping of urinary bladder when there is no any disturbing organ associated impediments.
  • It was previously used in case of stomach attorney and gastroesophageal reflex but nowadays there are more effective drugs
16
Q

what are the side effects of M cholinomimetic drugs?

A
  1. They are dose dependent
  2. marked bradycardia
  3. AV block at different degrees
  4. excessive sweating, salivation, and diarrhea
  5. optical disturbances
  6. headaches
17
Q

Which type of receptors do N cholinomimetic drugs activate?

A

They activate Nn receptors but only in high doses they’re able to activate Nm receptors

18
Q

describe the action of nicotine.

A

It exerts 2 phases of action at which initially it causes excitation and then depression phase

19
Q

describe the pharmacokinetics of nicotine.

A
  • Highly lipophilic
  • well absorbed from the mucous membranes of the respiratory tract and skin
  • rapidly penetrates the BBB
20
Q

what are the effects of nicotine on the central nervous system?

A
  1. In low doses it causes analgesia
  2. in high doses it causes tremor and stimulate the respiratory center
  3. in toxic doses it can cause convulsions and it can inhibit the respiratory center
  4. it increases the amount of dopamine, serotonin, and stimulatory amino acids
  5. it has an emetic action by central mechanism at which chemoreceptors of the trigger zone are stimulated and by peripheral mechanism I told you the vagal and spinal afferent nerves are stimulated
  6. it has an anti diuretic effect at which it stimulates the release of ADH from neuron hypothesis
21
Q

what is the effect of nicotine on the adrenal medulla?

A

At first it stimulates the receptors of chromaffin cells and increases the release of epinephrine but in depression it inhibits the release of epinephrine

22
Q

what are the effects of nicotine on the cardiovascular system?

A
  • At the beginning bradycardia occurs due to the stimulation of both vehicle centre and intramuscular parasympathetic ganglia and then it’s followed by tachycardia due to the activation of sympathetic ganglia and increase of epinephrine released from the adrenal medulla
  • increase of blood pressure due to stimulation of the vasomotor center and sympathetic ganglia as well as the increased release of epinephrine
23
Q

what is the effect of nicotine on GIT?

A

It stimulates the tone and motor activity of the intestine

24
Q

what is the effect of nicotine on exocrine glands?

A

At the beginning secretion of salivary and bronchial glands are stimulated and then inhibited

25
Q

what is the difference between nicotine and lobeline?

A

It is similar to nicotine but doesn’t have the phase of depression

26
Q

What is the usage of lobeline?

A

It was previously used as a smoking cessation drug and for treatment of drug abuse from amphetamine, cocaine, and alcohol

Pharmacology (11 decks)

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