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