Dose and Administration (See "Possible Adverse Effects")

1. Slow intravenous infusion of DILUTED paraldehyde.
   Administered as a 2 hour infusion ².
   Dose range is 0.2 to 0.4 ml (pure paraldehyde) /kg as 2 hour infusion.  This is equivalent to 4 to 8ml (of DILUTED SOLUTION ) /kg.– see Administration.
   The dose may be repeated to NOT MORE than 0.4ml (pure paraldehyde)/kg in 24 hours.
2. Rectal enema: 0.2 to 0.3ml (of pure paraldehyde)/kg (this volume of paraldehyde must be diluted before administration) ⁹ - see Administration.

Indications (For term or near term infants)

1. Seizure/status epilepticus refractory to initial therapy with phenobarbitone and phenytoin.

Contraindications

1. Known hypersensitivity to paraldehyde.
2. Severe hepatic insufficiency, bronchopulmonary disease ⁵, or gastric disease.

Precautions

1. Hepatic dysfunction.
2. Cardiovascular disease ⁵.
3. Use only freshly opened ampoules. Do not use paraldehyde if it is brownish colour or has a sharp penetrating odour of acetic acid – this indicates decomposed paraldehyde which is dangerous if administered ^5..
4. Avoid contact between paraldehyde and rubber; avoid use of plastic syringes because of solvent action of paraldehyde.

Drug Interactions

Possible concomitant drug therapy

Clinical Pharmacology

Paraldehyde is a hypnotic and sedative with anticonvulsant effects. Its possible action is to depress parts of the CNS including the ascending reticular activating system to cause an imbalance between inhibitory and facilitatory mechanisms ⁵. The drug is used to control seizures in infants, including those refractory to phenobarbitone and phenytoin, and is as effective as phenobarbitone in the emergency treatment of convulsions in children. Adult metabolism of paraldehyde involves 80% conversion to acetaldehyde, which is oxidised by aldehyde dehydrogenase to acetic acid. Unmetabolised drug is largely excreted unchanged through the lungs with a smaller amount excreted in the urine ⁶. The drug diffuses into the CSF and has a rapid onset of action. At therapeutic doses, paraldehyde has little effect on respiration and blood pressure ⁵.

Possible Adverse Effects

1. Intravenous injection may be hazardous and may cause pulmonary oedema and haemorrhage, hypotension and cardiac dilatation, and circulatory collapse ⁵.
2. Rectal administration may result in rectal irritation.
3. Skin rash; trembling; unusual sweating ⁵.
4. Overdosage manifests as rapid laboured breathing, due to damage to lungs and to acidosis. Respiratory depression and coma; metabolic acidosis, hepatic and renal damage may also occur ⁶. Diagnosis of paraldehyde overdose may be aided by the characteristic odour of the drug on the breath ⁶.
5. Gastrointestinal irritation.

Special Considerations

1. Emergency action for overdosage:  Supportive measures:
   • Ventilation
   • Correction of hypotension
   • Correction of metabolic acidosis