NTA Level 4 • Semester 2 • PST04211

Description of Muscle Relaxants and Cholinesterase Inhibitors

Basic Pharmacology • Source Session/Topic 41

Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability.

Session 41: Description of Muscle Relaxants and

Cholinesterase Inhibitors

Total Session Time: 120 minutes

Prerequisite module

• None

Learning Tasks

By the end of this session students are expected to be able to:

• List indications of muscle relaxants and cholinesterase inhibitors

• List Contraindication of muscle relaxants and cholinesterase inhibitors

• Describe dose, dosage and course of muscle relaxants and cholinesterase inhibitors

• List side effects and adverse effects of muscle relaxants and cholinesterase inhibitors

• Describe interaction and precaution of muscle relaxants and cholinesterase inhibitors

Resources Needed:

• Flip charts, marker pens, and masking tape

• Black/white board and chalk/whiteboard markers

• Computer and overhead projector

SESSION OVERVIEW

Activity/

Step Time Content

Method

1 05 minutes Presentation Introduction, Learning tasks

Presentation/ Listing Indications of Muscle Relaxants and

2 20 minutes

Buzzing Cholinesterase Inhibitors

Presentation/ Listing Contraindication of Muscle Relaxants

3 20 minutes

brainstorming and Cholinesterase Inhibitors

Description of Dose, Dosage and Course of

4 30 minutes Presentation Muscle Relaxants and Cholinesterase

Inhibitors

Listing Side Effects and Adverse Effects of

Presentation/

5 20 minutes Muscle Relaxants and Cholinesterase

brainstorming

Inhibitors

Description of Interaction and Precaution of

6 15 minutes Presentation Muscle Relaxants and Cholinesterase

Inhibitors

7 05 minutes Presentation Key Points

8 05 minutes Presentation Evaluation

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SESSION CONTENTS

STEP 1: Presentation of Session Title and Learning tasks (5 minutes)

READ or ASK students to read the learning objectives and clarify

ASK students if they have any questions before continuing.

STEP 2: Indications of Muscle Relaxants and Cholinesterase Inhibitors

(20 minutes)

Activity: Buzzing (5 minutes)

ASK students to pair up and buzz on the following question for 2 minutes

• What are muscle relaxants and cholinesterase inhibitors?

• What are the indications of muscle relaxants and cholinesterase inhibitors?

ALLOW few pairs to respond and let other pairs add on points not mentioned

WRITE their response on the flip chart/board

CLARIFY and SUMMARIZE by using the content below

• Muscle relaxants are also known as neuromuscular blocking drugs. They include:

Gallamine, Suxamethonium Chloride, Vecuronium Bromide, and Pancuronium Bromide.

Anti-cholinesterase includes Edrophonium and Neostigmine

• They are used in anaesthesia

o They enable light anaesthesia to be used with adequate relaxation of the muscle

o Gallamine is used to produce relaxation of skeletal muscle during surgery

o Suxamethonium Chloride is used for short to intermediate duration neuromuscular

blockade for surgery or during intensive care

o Vecuronium Bromide is used for intermediate duration neuromuscular blockade

for surgery or during intensive care

o Pancuronium Bromide is used for long duration neuromuscular blockade

for surgery or during intensive care

• Anticholinesterases reverse the effects of the non-depolarising (competitive)

neuromuscular blocking drugs such as pancuronium but they prolong the action of

depolarizing neuromuscular blocking drugs

o Edrophonium has a transient action and may be used in the diagnosis of suspected

dual block due to suxamethonium

o Neostigmine has a longer duration of action than edrophonium and is used

specifically for reversal of nondepolarising (competitive) blockade

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STEP 3: Contraindication of Muscle Relaxants and Cholinesterase

Inhibitors (20 Minutes)

Activity: Brainstorming (5 minutes)

Ask students to brainstorm on the following question:

• What are the Contraindication of muscle relaxants and cholinesterase inhibitors?

ALLOW few students to respond

WRITE their responses on the flip chart/ board

CLARIFY and SUMMARISE by using the content below

• Most muscle relaxants are not contraindicated to any specific individuals except

Suxamethonium and galamine chloride which is contraindicated to those with:

o Family history of malignant

o Hyperthermia

o Hyperkalaemia

o Major trauma

o Severe burns

o Neurological disease involving acute wasting of major muscle

o Prolonged immobilisation

o Hyperkalaemia

o Low plasma-cholinesterase activity (including severe liver disease)

• Cholineaterase inhibitors are contraindicated in

o Intestinal obstruction

o Urinary obstruction

STEP 4: Dose, Dosage and Course of Muscle Relaxants and Cholinesterase

Inhibitors (30 minutes)

• Dose dosage and course of muscle relaxants

o Atracurium Besilate:

 Surgery or intubation, adult and child over 1 month, by intravenous injection, initially

300–600 micrograms/kg, then 100–200 micrograms/kg as required

 Intensive care, ADULT and CHILD over 1 month, by intravenous injection, initially

300–600 micrograms/kg then by intravenous infusion 4.5–29.5 micrograms/kg/minute

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o Suxamethonium Chloride

 By intravenous injection, initially 1 mg/kg; maintenance, usually 0.5–1 mg/kg at 5–10

minute intervals; max. 500 mg/hour; CHILD under 1 year, 2 mg/kg; CHILD over 1

year, 1 mg/kg

 By intravenous infusion of a solution containing 1–2 mg/mL (0.10.2%), 2.5–4

mg/minute; max. 500 mg/hour; CHILD reduce infusion rate according to body-

weight

 By intramuscular injection, CHILD under 1 year, up to 4–5 mg/kg; CHILD over 1

year, up to 4 mg/kg; max

o Gallanium

 Adults: 1-1.5 mg/kg i.v. initially, then 0.5-1 mg/kg as required at about 40-minute

intervals

 Children: 1.5 mg/kg initially, then 0.5 mg/kg as required

 Infants of less than 1 month: 250-750 micrograms/kg initially, then 100-500

micrograms/kg

o Mivacurium

 Intravenous injection, 70–250 micrograms/kg; maintenance 100 micrograms/kg every

15 minutes

 CHILD 2–6 months initially 150 micrograms/kg, 7 months–12 years initially 200

micrograms/kg

o Vecuronium Bromide

 By intravenous injection, intubation, adult and child, initially 80–100 micrograms/kg;

maintenance 20–30 micrograms/kg adjusted according to response; neonate

 By intravenous infusion, 0.8–1.4 micrograms/kg/minute (after initial intravenous

injection of 40–100 micrograms/kg)

o Pancuronium Bromide

 Intubation, by intravenous injection, initially 50–100 micrograms/kg then 10–20

micrograms/kg as required: Intensive care, by intravenous injection, 60

micrograms/kg every 60–90 minutes

• Dose dosage and course of cholinesterase inhibitors

o Edrophonium

Is given by intravenous injection over several minutes, 500–700 micrograms/kg (after

or with atropine)

o Neostigmine

Is given by intravenous injection over 1 minute, 50–70 micrograms/kg (max. 5 mg)

after or with atropine

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STEP 5: Side Effects and Adverse Effects of Muscle Relaxants and

Cholinesterase Inhibitors (20 minutes)

Activity: Brainstorming (5 minutes)

Ask students to brainstorm on the following question:

• What are the side effects and adverse effects of muscle relaxants and cholinesterase?

ALLOW few students to respond

WRITE their responses on the flip chart/ board

CLARIFY and SUMMARISE by using the content below

• Side and adverse effects of muscle relaxants

o Atracurium, has Cardiovascular effects are associated with significant histamine

release

o Gallamine may produce vagolytic tachycardia. Anaphylactoid reactions rarely occur

o Pancuronium causes tachycardia and hypertension

o Rocuronium high doses produce mild vagolyti activity

o Vecuronium, it does not generally produce histamine release and lacks cardiovascular

effects

• Side effects of cholinesterase inhibitor in normal dose include:

o Nausea

o Vomiting

o Increased salivation

o Diarrhoea

o Abdominal cramps

• In overdosage

o Bronchoconstriction

o Increased bronchial secretions

o Lacrimation

o Excessive sweating

o Involuntary defaecation and

o Micturition

o Miosis

o Nystagmus

o Bradycardia, heart block, arrhythmias, hypotension, agitation

o Excessive dreaming

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STEP 6: Interaction and Precaution of Muscle Relaxants and

Cholinesterase Inhibitors (20 minutes)

• Interaction and precaution of muscle relaxants

• Suxamethonium

o Interaction

 Action of Suxamethonium is enhanced by donepezil

o Pre Caution is advised in:

 Hypersensitivity to these drugs

 Myasthenia gravis

 Hypothermia

 Neuromuscular disorders

 Electrolyte disturbances

• Gallamine

o Precautions; Gallamine should be used, whenever possible, by an experienced

specialist anaesthetist. Facilities for endotracheal intubation and mechanically assisted

ventilation should be immediately to hand and ready for use

• Interaction and precaution cholinesterase inhibitors

o Interactions:

 Action of neostigmine is antagonized by lithium and propranolol

o Caution is advised in:

 Asthma (extreme caution)

 bradycardia

 Arrhythmias

 Recent myocardial infarction

 Epilepsy, hypotension, parkinsonism, vagotonia, peptic ulceration

 Hyperthyroidis

 Neostigmine is antagonized by lithium and propranolol

STEP 7: Key points (5 minutes)

• Muscle relaxants are used together with anesthesia in surgery or intubation

• Anticholinesterases drugs are used to reverse the effects of the non-depolarising

neuromuscular blocking drugs such as but they prolong the action of depolarizing

neuromuscular blocking drugs

• Action of Suxamethonium is enhanced by donepezil

• Neostigmine is antagonized by lithium and propranolol

STEP 7: Evaluation (5 minutes)

• What are the indications of muscle relaxants?

• What are the indications of cholinesterase inhibitors?

• Which drug enhances the action of suxamethonium?

• What will happen in anticholinesterase overdose?

• What is the precaution on the use of gallamine?

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References

Ministry of Health and Social Welfare. (2013). Standard Treatment Guidelines & National

Essential Medicines List Tanzania Mainland (4th ed.). Dar es salaam, Tanzania

government printers.

Robert L. Talbert, Gary C. Yee, Gary R. Matzke, Barbara G. Wells, L. Michael. 2014.

Pharmacotherapy: A Pathophysiologic approach (9th ed.). New York, McGraw-Hill

Education.

Sally S.R, Jeanne C.S. (2000). Introductory Clinical Pharmacology (6th ed) New York,

Lippincott Williams and Wilkins.

School of Pharmaceutical sciences. (2011).Tanzania Pharmaceutical Handbook (2nd ed.).

Dar es Salaam, ARDHI University press.

The Royal Pharmaceutical Society of Great Britain. 2007. Martindale, The Extra

Pharmacopoeia (5TH ed). London, pharmaceutical press.

The Royal Pharmaceutical Society of Great Britain. 2009. British National Formulary

(59th ed). London, BMJ Group and RPS Publishing.

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