Goodnight Solution Contents
Goodnight is a brand name product containing promethazine hydrochloride as its active ingredient, formulated as an oral liquid solution. 1
Active Ingredient
- Promethazine hydrochloride is the sole active pharmaceutical ingredient in Goodnight solution 1
- Promethazine is a first-generation phenothiazine antihistamine with H1-receptor antagonist properties 2, 3
Pharmacological Properties of the Active Ingredient
- Mechanism of action: Promethazine works through histamine H1-receptor antagonism, dopaminergic blockade, alpha-adrenergic inhibition, and anticholinergic effects 3
- The compound possesses antihistamine, sedative, antiemetic, and anticholinergic properties 2
Clinical Context and Formulation
- Goodnight became available on the New Zealand market in December 1994 as an unrestricted, pharmacy-only medication 1
- The liquid formulation (syrup) provides ease of administration, which contributed to both its popularity and misuse potential 4
- Each full box of Goodnight contains sufficient promethazine to cause significant toxicity in overdose, as 60% of overdose patients in one case series ingested one or more full boxes 1
Important Safety Considerations
- The liquid formulation and over-the-counter availability led to high morbidity from overdoses, with 48% of overdose patients requiring intensive care admission and 33% requiring intubation 1
- Promethazine can cause respiratory depression, hypotension, extrapyramidal effects, neuroleptic malignant syndrome, and seizures, particularly when combined with other CNS depressants 2, 3
- The sedative effects are substantial, with first-generation antihistamines like promethazine causing 60-73% sedation rates compared to second-generation alternatives 2