Nitrous Oxide

Registered South African indications:

• General anaesthesia 

Contraindications

• Hypersensitivity to the active ingredient or any of its excipients
• Should not be administered without oxygen
• Abdominal distensions
• Pneumothorax
• Pneumopericardium
• Bullae in the lungs 
• Middle ear surgery

Cautions

• Increased intracranial pressure
• Head injuries
• Space occupying intracranial lesions
• Pulmonary hypertension
• Major bowel surgery or any type of ileus
• Vitamin B12 deficiency
• Dihydropteridine reductase deficiency
• Other nutritional deficiencies
• Bleomycin chemotherapy

Forms avail. in SA and covered in this monograph: gas

Anaesthesia - induction and maintenance 

• Inhaled (gas): Nitrous oxide 70% mixed with 30% oxygen as an adjunct to potent inhalational agents 

Nitrous oxide should not be administered without oxygen 

Max. treatment duration: 24 hours of continuously inspired nitrous oxide 

See adult dosage 

Pregnancy

• FDA Pregnancy Category Not Rated (NR)

Breastfeeding

• Compatible

Renal Impairment

• No dose adjustment recommended

Hepatic Impairment

• No dose adjustment recommended 

Elderly

• No dose adjustment recommended

Central Nervous System Disorders

• Myeloneuropathies
• Neuropathies 
• Psychosis 

Cardiovascular Disorders

• Arrhythmias
• Hypotension

Respiratory Disorders

• Hypoxia

Immune, Blood and Lymphatic System Disorders

• Folate deficiency
• Myelosuppression 

Sensory Disorders

• Increase in middle ear pressure

Others

• Malignant hyperthermia

• Central nervous system depressants
• St John’s wort

None routine

Nitrous oxide induces opioid peptide release in the brain stem, resulting in activation of opioid receptors and descending GABA and noradrenergic pathways that modulate nociceptive processing at the spinal level.
 

Gas 

• Nitrous oxide (Afrox)

COMBINATION PREPARATIONS

Nitrous Oxide/ Oxygen

• Entonox (Afrox)