Oral Respiratory tract infections associated with excessive and/or viscous mucus
Adult: Available preparation:
Each bottle contains carbocisteine 100 mg and promethazine hydrochloride 2.5 mg
15 mL tid. Child: Each bottle contains carbocisteine 100 mg and promethazine hydrochloride 2.5 mg <2 years Not recommended. 2-5 years 2.5-5 mL four times a day. 6-12 years 7.5-12.5 mL tid. 12-15 years 12.5-15 mL tid.
Contraindications
Active peptic ulcer. Children <2 years.
Special Precautions
Patient with epilepsy, signs and symptoms suggestive of Reye’s syndrome. Children >2 years. Pregnancy and lactation.
Adverse Reactions
Significant: Anticholinergic effects (e.g. blurred vision, dry mouth, urinary retention). Drowsiness, dizziness, restlessness, headache, nightmare, tiredness, disorientation, photosensitivity. Gastrointestinal disorders: Nausea, gastric discomfort, GI bleeding, diarrhoea. Skin and subcutaneous tissue disorders: Rarely, rash, urticaria, pruritus. Potentially Fatal: Respiratory depression and apnoea especially in children.
Patient Counseling Information
Avoid prolonged exposure to sunlight.
Monitoring Parameters
Monitor mental status, and CNS effects (e.g. sedation).
Drug Interactions
May potentiate the effects of antihypertensive agents, other CNS depressants, MAOI(s) and analgesics.
Food Interaction
May enhance the CNS depressant effect of alcohol.
Lab Interference
Promethazine: May interfere with immunological urine pregnancy test to produce false-positive or false-negative results. Increased serum glucose may be seen with glucose tolerance tests. May lead to a false-positive result with urine detection of amphetamine/methamphetamine. May alter the flare response in intradermal allergen tests.
Action
Description: Mechanism of Action: Carbocisteine is a mucolytic agent that reduces goblet cell hyperplasia in the management of respiratory disorders associated with abnormally excessive or viscous mucus secretion.
Promethazine is a phenothiazine derivative which blocks postsynaptic mesolimbic dopaminergic receptors in the brain. It exhibits a strong α-adrenergic blocking effect and depresses the release of hypothalamic and hypophyseal hormones. It competes with histamine for the H1-receptor; muscarinic blocking effect may be responsible for antiemetic activity. It also reduces stimuli to the brainstem reticular system. Onset: Promethazine: Approx 20 minutes. Pharmacokinetics: Absorption: Carbocisteine: Rapidly and well absorbed from the gastrointestinal tract. Time to peak plasma concentration: Approx 2 hours.
Promethazine: Rapidly and well absorbed. Bioavailabilty: Approx 25%. Time to peak plasma concentration: 2-3 hours. Distribution: Carbocisteine: Penetrates into lung tissue and respiratory mucus.
Promethazine: Crosses the blood-brain barrier and placenta; enters breast (small amounts). Volume of distribution: 13.3 ± 3.6 L/kg. Plasma protein binding: 76-93%. Metabolism: Carbocisteine: Metabolised via acetylation, decarboxylation, and sulfoxidation by genetic polymorphism.
Undergoes extensive hepatic-first pass metabolism via hydroxylation by CYP2D6 and N-demethylation by CYB2B6. Excretion: Carbocisteine: Via urine, as unchanged drug and metabolites.
Promethazine: Via urine; faeces, as metabolites. Elimination half-life: Approx 5-14 hours.
Chemical Structure
Carbocisteine Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 193653, Carbocysteine. https://pubchem.ncbi.nlm.nih.gov/compound/Carbocysteine. Accessed Mar. 29, 2022.
Promethazine Source: National Center for Biotechnology Information. PubChem Database. Promethazine, CID=4927, https://pubchem.ncbi.nlm.nih.gov/compound/Promethazine (accessed on Jan. 21, 2020)
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