1. Dr. Ali Mohammad Ali Mohammadi FORENSIC MEDICINE AND TOXICOLOGY .
METHANOL POISONING
Dr. Ali Mohammad Ali Mohammadi
FORENSIC MEDICINE AND TOXICOLOGY .

2. MECHANISM OF ACTION METHANOL FORMALDEHYDE FORMIC ACID
ALCOHOL DEHYDROGENASE
ALDEHYDE DEHYDROGENASE
METHANOL
FORMALDEHYDE
FORMIC
ACID
METHANOL ITSELF NOT TOXIC. FORMALDEHYDE VERY TOXIC, BUT VERY RAPIDLY METABOLISED TO FORMIC ACID. FORMIC ACID RESPONSIBLE FOR THE TOXICITY RELATED TO METHANOL INGESTIONS

3. MECHANISM OF ACTION OCULAR TOXICITY CIRCULUS HYPOXICUS
METHANOL
OCULAR
TOXICITY
FORMALDEHYDE
INHIBITION OF MITOCHONDRIAL RESPIRATION
INCREASED FORMIC ACID TOXICITY
FORMIC
ACID
CIRCULATORY
FAILURE
CIRCULUS
HYPOXICUS
TISSUE
HYPOXIA
ACIDOSIS
ACIDOSIS
LACTIC ACID
PRODUCTION
Early stage
of poisoning
GENERAL TOXICITY

4. SIGNS AND SYMPTOMS INITIAL INEBRIATION - ESPECIALLY IF ETHANOL
COINGESTED
AFTER HOUR DELAY - PROGRESSION TO ACIDOSIS
AND OTHER SIGNS AND SYMPTOMS
MAY BE FURTHER DELAY WITH CONTINUED INGESTION
OF ETHANOL

5. SIGNS AND SYMPTOMS CNS - INEBRIATION PROGRESSING TO COMA, CONVULSIONS
RETINAL - BLURRED VISION, PHOTOPHOBIA, VISUAL
ACUITY LOSS, DILATED NON-REACTIVE PUPILS,
OPTIC NERVE HYPERAEMIC - BECOMING OEDEMATOUS
GIT - NAUSEA, VOMITING
CARDIAC - TACHYCARDIA, HYPERTENSION PROGRESSING
TO HYPOTENSION AND CARDIOGENIC SHOCK
RESPIRATORY - TACHYPNOEA

6. INVESTIGATION BLOOD METHANOL LEVEL! ABG - METABOLIC ACIDOSIS
OSMOLAL GAP - INCREASED (METHANOL)
ANION GAP - INCREASED (FORMIC ACID, LACTIC ACID)
BLOOD ETHANOL
MAGNESIUM, AMYLASE, POTASSIUM

7. Lab ABG – metabolic acidosis
Creatinine, BUN & lytes – increased anion gap
Increased Osmolal gap
Osmolal gap = measured osmolality – calculated osmolality
Calculated osmolality = 2 x Na + glucose in mm/L +
BUN in mm/L + Ethanol in mm/L

8. Osmolal Gap cont’d
Can’t tell whether toxic alcohol is Methanol, Ethanol, Ethylene Glycol or Isopropyl Alcohol
Only increased by parent alcohols therefore not good for late presentation

9. TREATMENT HAZARD ASSESSMENT ABC’s TOXICOKINETICS ABSORPTION
DISTRIBUTION
METABOLISM
ELIMINATION
TOXICODYNAMICS
SUPPORTIVE CARE

10. TREATMENT CORRECTION OF METABOLIC ACIDOSIS
BICARBONATE (AGGRESSIVE TREATMENT)
CAN REVERSE VISUAL IMPAIRMENT
REDUCES MOVEMENT OF FORMATE TO THE CNS
MAY REQUIRE 400 TO 600 MMOL DURING FIRST FEW HOURS
REHYDRATION

11. MECHANISM OF ACTION METHANOL FORMALDEHYDE FORMIC ACID
ALCOHOL DEHYDROGENASE
ALDEHYDE DEHYDROGENASE
METHANOL
FORMALDEHYDE
FORMIC
ACID

12. MECHANISM OF ACTION X METHANOL ETHANOL ALDEHYDE ACETIC ACID
FORMALDEHYDE
FORMIC
ACID
ALCOHOL DEHYDROGENASE
ALDEHYDE DEHYDROGENASE
ETHANOL
ALDEHYDE
ACETIC
ACID

13. (REDUCES FORMATION OF TOXIC METABOLITES)
TREATMENT
ETHANOL
(REDUCES FORMATION OF TOXIC METABOLITES)
MAINTAIN BLOOD ETHANOL LEVEL OF mg/dl
LOADING DOSE
BEWARE OF EXISTING ETHANOL LEVEL
MAINTENANCE DOSE
TITRATED AGAINST RATE OF ELIMINATION
NON-ALCOHOLIC mg/dl/h
CHRONIC ALCOHOLIC mg/dl/h
CHILD 30 mg/dl/h

14. TREATMENT ETHANOL INDICATIONS BLOOD METHANOL LEVELS GREATER THAN
6.25 mmol/l (20 mg/dl)
IF HAEMODIALYSIS IS TO BE COMMENCED

15. TREATMENT ETHANOL HALF LIFE OF METHANOL IS USUALLY 15 - 30 HOURS
HALF LIFE OF METHANOL WITH ETHANOL TREATMENT
IS HOURS
YOU MAY THEREFORE HAVE A NON-SOBER PATIENT ON
THE WARD FOR SEVERAL (4 - 5) DAYS...

16. TREATMENT HAEMODIALYSIS METHANOL LOW MOLECULAR WEIGHT
NOT PROTEIN BOUND
LOW VOLUME OF DISTRIBUTION
THEREFORE IDEAL FOR HAEMODIALYSIS

17. TREATMENT HAEMODIALYSIS INDICATIONS ANY DEGREE OF VISUAL IMPAIRMENT
SEVERE METABOLIC ACIDOSIS
BLOOD METHANOL LEVEL GREATER THAN
15 mmol/l (50mg/dl)

18. METABOLISM METHANOL FORMALDEHYDE FORMIC ACID CO2 and H2O
ALCOHOL DEHYDROGENASE
ALDEHYDE DEHYDROGENASE
METHANOL
FORMALDEHYDE
FORMIC
ACID
FOLIC ACID
THF
MAGNESIUM
CO2 and H2O

19. TREATMENT FOLINIC ACID/FOLIC ACID
50 mg IV EVERY FOUR HOURS FOR 24 HOURS, OR WHILE
FORMIC ACID MAY STILL BE ACCUMULATING
MAGNESIUM
MgSO4 TITRATED AGAINST BLOOD MAGNESIUM LEVELS

20. METHYLATED SPIRITS METHYLATED SPIRITS IS 5% METHANOL, 95% ETHANOL
ACUTE INGESTION PRESENTS AS ETHANOL, RATHER THAN
METHANOL, POISONING
METHANOL INTOXICATION IS ONLY A CONCERN IF METHYLATED
SPIRSTS IS INGESTED CHRONICALLY

21. METHYLATED SPIRITS EXAMPLE IF 250 ml METHYLATED SPIRITS INGESTED:
BLOOD ETHANOL LEVEL = 450 mg/dl (LD50)
BLOOD METHANOL LEVEL = 24 mg/dl

22. METHYLATED SPIRITS EXAMPLE
IF 1.5 l METHYLATED SPIRITS INGESTED OVER SEVERAL
DAYS:
BLOOD ETHANOL LEVEL ~ 450 mg/dl (LD50)
BLOOD METHANOL LEVEL = 142 mg/dl
(IN 12 HOURS ETHANOL LEVEL = 100 mg/dl
METHANOL LEVEL = 124 mg/dl)