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Neurology Articles > Drugs that worsen MG > Flashcards

Drugs that worsen MG Flashcards

1
Q

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

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

Average time from ICI initiation to MG symptoms onset

A

4 weeks, ranging from 1 week to 4 months

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3
Q

AChR Ab seropositivity in ICI-associated MG patients

A

Present in about two-thirds of patients

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4
Q

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

A

45%

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5
Q

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

A

25-40%

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6
Q

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

A

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

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7
Q

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

A

Overlapping cases have a worse prognosis.

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8
Q

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

A

Overlap syndrome of MG, myositis, and myocarditis.

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9
Q

What is recommended for MG patients treated with ICIs?

A

MG patients should be on maintenance steroid treatment.

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10
Q

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

A

Use of PLEX or IVIG treatment improves the outcome.

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11
Q

What percentage of patients taking D-penicillamine develop MG?

A

1-7%

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12
Q

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

A

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

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13
Q

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

A

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

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14
Q

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

A

Immune dysregulation or direct effect on neuromuscular transmission.

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15
Q

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

A

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

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16
Q

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

A

IFN alpha

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17
Q

What do authors suggest regarding macrolide use in MG patients?

A

Avoid macrolides if there is another alternative.

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18
Q

Why should fluoroquinolones be avoided in MG patients?

A

They directly affect the AChR ion channel.

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19
Q

Aminoglycosides effect on MG patients

A

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

20
Q

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

A

Tobramycin

21
Q

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

A

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

22
Q

Which drugs can be safely administered to MG patients?

A

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

23
Q

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

A

They may cause transient exacerbation of MG symptoms.

24
Q

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

A

MG patients in remission or well controlled.

25
Q

How does Chloroquine cause MG?

A

Emergence of myasthenia through AChR antibodies

26
Q

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

A

Hydroxychloroquine

27
Q

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

A

MG-like symptoms

28
Q

What effect does propafenone have on MG symptoms?

A

Causes worsening of MG symptoms within hours.

29
Q

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

A

Class Ib antiarrhythmics such as flecainide and amiodarone.

30
Q

What condition may statins exacerbate or induce?

A

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

31
Q

Why should magnesium supplementation be used cautiously in MG patients?

A

It can exacerbate symptoms in myasthenia gravis patients.

32
Q

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

A

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

33
Q

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

A

Succinylcholine

34
Q

True/False:

AchEI can reverse succinylcholine

A

False. In fact succinylcholine effects can be enhanced by AchEI

35
Q

Is succinylcholine absolutely contraindicated in MG?

A

No, it is not absolutely contraindicated in MG.

36
Q

How do MG patients respond to nondepolarizing neuromuscular blockers?

A

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

37
Q

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

A

Halothane, isoflurane, enflurane, and sevoflurane.

38
Q

What is Sugammadex?

A

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

39
Q

What is a key advantage of sugammadex over acetylcholinesterase inhibitors?

A

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

40
Q

Which was the first typical antipsychotic associated with MG exacerbation?

A

Chlorpromazine

41
Q

Which antipsychotics are reported to worsen symptoms in MG patients?

A

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

41
Q

Which atypical antipsychotics affect neuromuscular transmission?

A

Clozapine, olanzapine, sulpiride, risperidone

42
Q

What happens to myasthenic symptoms after starting lithium?

A

They emerge shortly after starting lithium.

43
Q

What is the conclusion about antiepileptics in MG patients?

A

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

44
Q

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

A

MuSK positive myasthenia gravis (MG).

45
Q

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

A

It should preferably be avoided in MG patients.

Neurology Articles (9 decks)

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