Methyl Alcohol (Methanol) Poisoning

MECHANISM OF ACTION

METHANOL FORMALDEHYDE FORMICACID

ALDEHYDE DEHYDROGENASEALCOHOL DEHYDROGENASE

METHANOL ITSELF NOT TOXIC. FORMALDEHYDE VERY TOXIC, BUT VERY RAPIDLY METABOLISED TO FORMIC ACID. FORMIC ACID RESPONSIBLE FOR THE TOXICITY RELATED TO METHANOL INGESTIONS

MECHANISM OF ACTIONMETHANOL

FORMALDEHYDE

FORMICACID

ACIDOSIS

Early stageof poisoning

ACIDOSISTISSUE

HYPOXIA

LACTIC ACIDPRODUCTION

CIRCULATORYFAILURE

GENERAL TOXICITY

INCREASED FORMIC ACID TOXICITY

OCULARTOXICITY

INHIBITION OF MITOCHONDRIAL RESPIRATION

CIRCULUSHYPOXICUS

SIGNS AND SYMPTOMS

In small doses Dizziness (vertigo) Headache

Nausea & Vomitting Abdominal pain

In Moderate doses Tachy cardia Drowsiness Mydriasis (dilation of the pupil)

In High doses Metabolic Acidosis Convulsions Retinal Oedema COMA Respiratory failure and death

SIGNS AND SYMPTOMS

CNS – CONVULSIONS, PROGRESSING TO COMA

RETINAL - BLURRED VISION, PHOTOPHOBIA, VISUAL ACUITY LOSS, DILATED NON-REACTIVE PUPILS,OPTIC NERVE BECOMES OEDEMATOUS

GIT - NAUSEA, VOMITING

CARDIAC - TACHYCARDIA, HYPERTENSION PROGRESSINGTO HYPOTENSION AND CARDIOGENIC SHOCK

RESPIRATORY - TACHYPNOEA

INVESTIGATION

BLOOD METHANOL LEVEL (by titration method)

ABG

Fundoscopy ( to examine retinal

Image reference http://www.meajo.org/article.asp?issn=0974-9233;year=2013;volume=20;issue=1;spage=92;epage=94;aulast=Iscan

TREATMENT

(i) ABC

(ii) CORRECTION OF METABOLIC ACIDOSISBICARBONATE (AGGRESSIVE TREATMENT)

(iii) Ethanol ( competitive binding to ADH)

(iv) Haemodialysis

(v) Folinic acid (elemination of formic acid)

(vi) Fomepizole

CASE STUDY

Name : Mr. X Age :58Sex : Male DOA : 27/7/13

CHIEF COMPLAINTS :

C/O Right Shoulder pain in the morning following which he faints and then goes into unconscious state convulsions (before going unconscious) (tongue bite mark seen)

HISTORY OF PRESENT ILLNESS :

N/K/C/O – BA / HTN / Epilepsy

Consumption of high levels of alcohol (12 hrs ago)

PAST MEDICAL HISTORY :

Known Diabetic, wound present over the right foot for over 7 months

PERSONAL HISTORY/ SOCIAL HABITS

K/C/O Alcoholism – 25 yrsSmoking – 14 yrs

PHYSICAL EXAMINATION :

Pt was Unconscious/ disoriented

ON EXAMINATION :Temp : 103° F BP : 110 / 70Pulse : 88 RR 16

SYSTEMIC EXAMINATION :

CVS: S1 S2 +ve CNS : pupils not responding (dilated)

Initially responded to painful stimuli

followed by no response

RS : NVBS P/A : Soft

Metabolic acidosis

Pt. Name is hidden

OTHER TESTS :

CT - subcortical white matter and basal ganglia hyperintensity and low-signal-intensity 

ECG – Bradycardia

DIAGNOSIS

Alcohol Poisoning ( Methyl Alcohol)

TREATMENT

Initially - Stomach wash given, Commercially available Ethanol 10 % soln (30 ml)

DRUGS DOSE R.O.A FREQ No of Days

Inj Fosolin (Fos Phenytoin)(anti convulsant)

150 mg IV stat 1

Inj Ceftum (cefuroxime) 250 mg IV OD 1

Inj Pantocid (pantoprazole)

40 mg IV BD 1

Inj Strocit ( citicoline)(a Neurotonics/Neurotrophics)

250 mg IV BD 1

Inj Lasix 20 mg IV Stat 1

Inj Sodium Bicarb 500 mL IV Stat 1

PROGNOSIS OF CASE

The Subject goes into irreversible COMA

Respiratory Depression occours ( put on mechanical ventilation)

Sudden Cardiac Failure

Death