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TOXIC MYOPATHIES

Amphiphilic drug myopathies
Biological toxins: Snake & others
Focal fibrosing myopathy
Hypokalemic myopathy
Inflammatory myopathy
Mitochondrial
Myalgia syndromes
Myosin Deficiency Myopathies
Myotonic syndromes
NMJ disorders
  Myasthenic syndromes: Drug-related
  Venoms & Toxins
Overactivity syndromes
Rhabdomyolysis
Toxic myopathies: Classification
e-Aminocaproic acid
Amiodarone
Apamin
Arsenic trioxide
AZT
Barium
Chlorophenoxy
Chloroquine
Ciguatoxin
Clofibrate
Colchicine
Corticosteroids
Crotamine
Crotoxin
Cyclosporine
Daptomycin
20,25-Diazacholesterol
Emetine
Ethanol
Fibrates
Gemcitabine
Germanium
Gold
Gossypol
Interferon-α
Ipecac
Isotretinoin
Lithium
Minocycline
Mojave toxin
Penicillamine
Pentaborane
Procainamide
Propofol
5-α Reductase
Selumetinib
Statins
Taipoxin
TNF-α
Toxic oil
L-Tryptophan
Valproate
Vecuronium bromide
Vinca alkaloids
Zidovudine


Classification of Toxic Myopathies

Cellular types
Other disorders: Clinical patterns
Amphiphilic Drug Myopathies
Apamin
Barium myopathy (Hypokalemic)
Anti-microtubule drugs: Myopathy
Cyclosporine myopathy 2: Several syndromes
Daptomycin 12
20,25-Diazacholesterol
Eosinophilia-Myalgia Syndrome 1

Gossypol myopathy
  • Sources
    • Thespesia populnea: Cotton plant flower
    • Gossypium herbaceum: Seed & Root
      • Predominant pigment
  • Intoxication route: Ingestion of raw cottonseed oil
  • Uses
    • Male contraceptive
    • Uterine hemorrhage (in China)
    • Animal feed: Cotonseed
  • Epidemiology
    • Location: Common in cotton growing areas of China
    • Seasonal: More common in Winter & Spring
  • Clinical
    • Prodrome: Nausea; Anorexia; Tingling in hands; Cramping; Weakness
    • Progression: Over 1 to 2 weeks
    • Polydipsia
    • Polyuria
    • GI: Anorexia; Nausea & vomiting
    • Palpitations
    • Weakness
      • Proximal > Distal
      • Other: Wrist weakness; Occasional respiratory
    • Tone reduced
    • Tendon reflexes: Reduced
    • Normal cranial nerves & sensation
    • Course: Resolution over weeks
  • Laboratory
    • Serum K+: Low
    • Urine: High K+; Distal renal tubular acidosis
    • EKG: Long QT; T wave change; PVC; AV block
  • Mechanism of myopathy: Hypokalemia
    • K+ wasting in urine
  • Treatment
    • Stop gossypol intake
    • K+ supplementation: IV or oral
  • Animal toxicity
    • Source: Cottonseed feed
    • Affected animals: Non-ruminants; Younger age
    • Sudden death
    • Cardiomyopathy

Gossypol

Ipecac myopathy
Emetine myopathy
Chlorophenoxy herbicides 4
Isotretinoin 6
Focal Fibrosing Myopathies 3
Tumor Necrosis Factor-α 8
Selumetinib 13
5-α reductase inhibitors 14
Return to Myopathy differential diagnosis
Return to Neuromuscular home page

References
1. Ann Int Med 1995;122:851-855, Toxicol Lett 2018;282:71-80
2. Muscle Nerve 1999;22:1631-1636
3. Muscle Nerve 2000;23:274-277
4. Clinical Toxicology 2000;38:111-122
5. Acta Neuropathol 2001;December, On-Line
6. Acta Derm Venereol 2001;81:350-352
7. BMJ 2002;324:1497
8. Am J Respir Crit Care Med 166;2002:479–484
9. Muscle Nerve 2003;Online January
10. Experimental Cell Research 2003;285:196–207
11. Medicine 2007;86:242-251, Muscle Nerve 2007 Nov 26
12. Muscle Nerve 2010;42:385–393
13. Neurology 2012;79:1929-1930
14. Pharmacoepidemiol Drug Saf 2018 Jan 25
15. Skelet Muscle 2019;9:27
16. J Clin Neuromuscul Dis 2018;20:94-98

11/15/2021