methanol sources , mechanism of toxicity , management , antidote , pharmacokinetices and others

1. Methanol
Formaldehyde
Toxicity

2. Methanol
Volatile

3. Methanol
Sources

4. Methanol
Sources
- Glass cleaner
- Inks
- Adhesives
- Lacquers
- carburetor fluid
- duplicator fluid
- Windshield washer fluid
May contain High concentrations of Methanol

5. Methanol
Routes
Of exposure

6. Methanol
Routes
Of exposure
Methanol absorbed rapidly in the
and blood vessels after
Orally
Both can result toxicity specially in the
Transdermal & Inhalation

7. Methanol
Routes
Of exposure
, , are also risk
for toxicity by inhalation
Inhalation
is a recent
trend that can result in toxicity

8. Methanol
Toxicokinetic

9. Methanol
Toxicokinetic
Itself has little toxicity than
the metabolites
Methanol
Metabolites of Methanol are extremely toxic
• Although Small amounts of Methanol are eliminated via renal and
pulmonary routes But
* metabolized Hepatically *

10. Methanol Formaldehyde Formic Acid
ADH FDH F-THF-S
H2O
CO2
Fomepizole or Ethanol Folinic acid or Folic acid
Metabolism of methanol.
ADH: Alcohol Dehydrogenase
FDH: Formaldehyde dehydrogenase;
F-THF-S: 10-Formyl Tetrahydrofolate Synthetase
All the toxic effects of methanol are due to formaldehyde and formic acid
Methanol
Toxicokinetic

11. Methanol metabolite is acidic  excreted in urine
Absorption
Highly absorbed from the GIT , reach for peak concentration within 30–60 min
½ life 2-3 hours
Distribution
Highly water soluble , highly plasma protein , small Vd so that 
Hemodialysis effect in enhance elimination
Elimination
Methanol
Toxicokinetic

12. Methanol
Toxicodynamic

13. Methanol
Toxicodynamic
CNS
Decrease consciousness
Induce comma
Seizures
Cerebral edema

14. Methanol
Toxicodynamic
Nausea
Vomiting
abdominal pain
Pancreatitis
liver function abnormality

15. Methanol
Toxicodynamic
visual disturbance
partial or total blindness due to effect on
optic nerve (cranial nerve 2)
Ophthalmological

16. Methanol
Toxicodynamic
CVS
Decrease cardiac output
Vasodilation
Hypotension

17. Induce DNA protein cross links
(DPX) which is genotoxic due to
their ability to arrest DNA
replication
Methanol
Toxicodynamic
Formaldehyde

18. Methanol
Toxicodynamic
Metabolic acidosis
• Methanol  formaldehyde  formic acid
• Hyperventilation  hyperpnea  depletion bicarbonate buffer
• Hypoglycemia  anaerobic glycolysis

19. Methanol
Clinical
Presentation

20. Methanol
Clinical
Presentation
1- decrease level of consciousness
2- Vomiting and abdominal pain
3- specific smell of breath
4- decrease vision may start as early as 12 hours after exposure
5- long term outcomes may include blindness and kidney failure
6- Necrosis of the distal portion of the optic nerve leads to atrophy

21. Fundoscopy:
Presence of papillitis indicated by hyperemic red optic disc ,
indicates formaldehyde toxicity when ophthalmic symptoms are
present
Methanol
Clinical
Presentation

22. Methanol
Factors
Affect toxicity of

23. Methanol
Factors
Affect toxicity of
• Hypoxemic agent such as Cyanide, Carbon mono-oxide
and Hydrogen sulfide
CNCyanide
H2SHydrogen sulfide

24. • Hypotension agents : Nitroglycerin , DHP
Calcium channel blockers
Methanol
Factors
Affect toxicity of

25. • Loop diuretics : Furosemide
Methanol
Factors
Affect toxicity of
• Enzyme inducers: Rifampicin

26. CNCyanide
H2SHydrogen sulfide

27. Methanol
Management
toxicity of

28. Investigation
For detection of methanol
and its products
For detection of Complications
due methanol products
• S.Methanol
• S.Formaldehyde
• Urine Formic Acid
• Fundoscopy
• ABG
• S. Lactate
• S. Electrolytes
Methanol
Management
toxicity of
.
.

29. Methanol
Management
toxicity of
A
B
C
D Ventilation
Circulation Support
I.V glucose
1- ABCD

30. Methanol
Management
toxicity of
Prevent any further absorption
• Gastric lavage
Emesis : using Ipecac syrup is contraindicated because
vomiting may cause aspiration
• Bowel irrigation
2- Decontamination

31. Methanol
Management
toxicity of
3-Enhance Elimination
- Hemodialysis is used because:
• Low molecular weights
• Hydrophilic
• Small Vd
- Alkalization for urine

32. Methanol
Management
toxicity of
Supportive treatment:
• Bicarbonate : is indicated for patients with
PH<7.3 to treat acidosis

33. • Hypoxia --> Ventilation
• Hypotension --> Vasopressor
• Hypoglycemia --> I.V Glucose
• Metabolic acidosis --> Bicarbonate
• Seizures --> Diazepam
Methanol
Management
toxicity of

34. Methanol
Management
toxicity of
Antidote :
• Fomepizole , Ethanol : to inhibit ADH by
limiting accumulation of Formate

35. Thank You•Rana Ali •Reem Saber •Reham Ashraf
•Sara Abdallah •Sara Hamza •Saad Fathy •Said Adel