Drugs that worsen MG

Question 1

What are the 2 general mechanisms by which a drug can cause MG or MG-like symptoms?

Answer 1

1. Eliciting an autoimmune reaction against the neuromuscular junction.
2. Interfering with neuromuscular transmission.
3. 1 and 2

Question 2

Average time from ICI initiation to MG symptoms onset

Answer 2

4 weeks, ranging from 1 week to 4 months

Question 3

AChR Ab seropositivity in ICI-associated MG patients

Answer 3

Present in about two-thirds of patients

Question 4

What percentage of patients with ICI-related MG experience respiratory failure?

Answer 4

45%

Question 5

What is the fatality rate for patients with ICI-related MG?

Answer 5

25-40%

Question 6

What percentage of ICI-induced MG cases overlap with myositis?

Answer 6

40% of ICI-induced MG cases overlap with myositis.

Question 7

What is the prognosis for overlapping cases of ICI-induced MG and myositis?

Answer 7

Overlapping cases have a worse prognosis.

Question 8

What is a rare but potentially fatal complication of ICI treatment?

Answer 8

Overlap syndrome of MG, myositis, and myocarditis.

Question 9

What is recommended for MG patients treated with ICIs?

Answer 9

MG patients should be on maintenance steroid treatment.

Question 10

What is recommended as the first line of treatment for MG patients treated with ICIs (beyond steroids)?

Answer 10

Use of PLEX or IVIG treatment improves the outcome.

Question 11

What percentage of patients taking D-penicillamine develop MG?

Answer 11

1-7%

Question 12

When do MG symptoms typically manifest after starting D-penicillamine?

Answer 12

MG symptoms manifest 6-7 months (but can be several years) after starting D-penicillamine.

Question 13

What percentage of MG cases go into complete remission after stopping D-penicillamine?

Answer 13

70% of MG cases go into complete remission after discontinuing D-penicillamine.

Question 14

What are the potential causes of MG by Tyrosine Kinase Inhibitors?

Answer 14

Immune dysregulation or direct effect on neuromuscular transmission.

Question 15

Is there a clear contraindication to using Tyrosine Kinase Inhibitors due to MG emergence?

Answer 15

No, emergence of MG is rarely reported, so no clear contraindication exists.

Question 16

What treatment in Hepatitis C patients can cause de novo myasthenia gravis or exacerbate myasthenia gravis?

Answer 16

IFN alpha

Question 17

What do authors suggest regarding macrolide use in MG patients?

Answer 17

Avoid macrolides if there is another alternative.

Question 18

Why should fluoroquinolones be avoided in MG patients?

Answer 18

They directly affect the AChR ion channel.

Question 19

Aminoglycosides effect on MG patients

Answer 19

Cause MG exacerbation and myasthenia-like symptoms in critically ill non-MG patients. Examples include Neomycin, Amikacin, streptomycin, gentamicin.

Question 20

Which aminoglycoside does not cause neuromuscular blockade at effective antibacterial concentrations?

Answer 20

Tobramycin

Question 21

Which class of antibiotics is recommended as first-line for MG patients?

Answer 21

Penicillins are recommended as first-line antibiotics for MG patients.

Question 22

Which drugs can be safely administered to MG patients?

Answer 22

Cephalosporins, sulfa drugs (eg TMP/SMX), clindamycin, tetracyclines, polymyxin B, nitrofurantoin.

Question 23

What effect can ß-adrenergic and calcium channel blockers have on MG symptoms?

Answer 23

They may cause transient exacerbation of MG symptoms.

Question 24

Who can generally undergo treatment with ß adrenergic or calcium channel blockers?

Answer 24

MG patients in remission or well controlled.

Question 25

How does Chloroquine cause MG?

Answer 25

Emergence of myasthenia through AChR antibodies

Question 26

Which drug similar to chloroquine has been reported to onset and exacerbate MG?

Answer 26

Hydroxychloroquine

Question 27

What symptoms has procainamide caused in nonmyasthenic patients with kidney failure?

Answer 27

MG-like symptoms

Question 28

What effect does propafenone have on MG symptoms?

Answer 28

Causes worsening of MG symptoms within hours.

Question 29

Which class of antiarrhythmics has no reports of worsening MG symptoms?

Answer 29

Class Ib antiarrhythmics such as flecainide and amiodarone.

Question 30

What condition may statins exacerbate or induce?

Answer 30

Statins may cause MG-like symptoms, MG exacerbation, and induction of de novo MG.

Question 31

Why should magnesium supplementation be used cautiously in MG patients?

Answer 31

It can exacerbate symptoms in myasthenia gravis patients.

Question 32

What is the mechanism of action for depolarizing neuromuscular blockers (NMBs)?

Answer 32

Depolarizing NMBs bind to AChR, causing activation and subsequent muscle relaxation as the AchR becomes insensitive to Ach.

Question 33

What is the only depolarizing neuromuscular blocker available in the US market?

Answer 33

Succinylcholine

Question 34

True/False: AchEI can reverse succinylcholine

Answer 34

False. In fact succinylcholine effects can be enhanced by AchEI

Question 35

Is succinylcholine absolutely contraindicated in MG?

Answer 35

No, it is not absolutely contraindicated in MG.

Question 36

How do MG patients respond to nondepolarizing neuromuscular blockers?

Answer 36

MG patients have prolonged and unpredictable block from nondepolarizing neuromuscular blockers (eg vecuronium, rocuronium, mivacurium) so use lower doses.

Question 37

Which inhaled anesthetics may cause neuromuscular block in MG patients similar to non depolarizing NMBs?

Answer 37

Halothane, isoflurane, enflurane, and sevoflurane.

Question 38

What is Sugammadex?

Answer 38

A y-cyclodextrin that encapsulates and reduces the activity of NMBs.

Question 39

What is a key advantage of sugammadex over acetylcholinesterase inhibitors?

Answer 39

Lack of increase in ACh at the neuromuscular junction, reducing postoperative complications.

Question 40

Which was the first typical antipsychotic associated with MG exacerbation?

Answer 40

Chlorpromazine

Question 41

Which antipsychotics are reported to worsen symptoms in MG patients?

Answer 41

Pimozide, thioridazine, clozapine, olanzapine, haloperidol, quetiapine, risperidone, olanzapine.

Question 41

Which atypical antipsychotics affect neuromuscular transmission?

Answer 41

Clozapine, olanzapine, sulpiride, risperidone

Question 42

What happens to myasthenic symptoms after starting lithium?

Answer 42

They emerge shortly after starting lithium.

Question 43

What is the conclusion about antiepileptics in MG patients?

Answer 43

Antiepileptics are generally safe in MG patients due to rarity of interaction reports.

Question 44

In which MG subtype may pyridostigmine be ineffective or worsen symptoms?

Answer 44

MuSK positive myasthenia gravis (MG).

Question 45

What is the recommendation for botulinum toxin A treatment in MG patients?

Answer 45

It should preferably be avoided in MG patients.