Products
Pholcodin is commercially available in many countries as a syrup (Phol-Tussil). It has been used medicinally since the 1950s.
Structure and properties
Pholcodine (C23H30N2O4, Mr = 398.50 g/mol) is a morpholinoethyl derivative of morphine and related to codeine. It is a white to almost white crystalline powder or colorless crystals and is sparingly soluble in water. According to the European Pharmacopoeia definition, pholcodine exists as pholcodine monohydrate (- H2O). The drug is structurally similar to some neuromuscular blockers such as suxamethonium.
Effects
Pholcodine (ATC R05DA08) has cough-irritant properties at the cough center and is mildly sedating. According to some sources, its structural modification makes it different from other opioids and, at least at therapeutic doses, it is reported to be nonpain-relieving, nonpsychotropic, nonstuffing, and nonrespiratory depressant. However, contradictory information on this can be found in the literature.
Indications
For symptomatic treatment of irritable cough.
Dosage
According to the drug label. Pholcodine is usually taken 2-4 times daily.
Contraindications
- Hypersensitivity
- Respiratory insufficiency
- Children under 2 years
- Asthma
- Strong mucus formation
- Severe hepatic and/or renal insufficiency.
- Pregnancy and lactation
Full precautions can be found in the drug label.
Interactions
Centrally depressant medications such as opioids, antidepressants, sleep aids, sedatives, or alcohol may increase adverse effects. Combination with other opioids may increase the risk of respiratory depression and other adverse effects of opioids.
Adverse effects
Possible adverse effects include constipation, nausea, vomiting, fatigue, drowsiness, lethargy, euphoria, dizziness, allergic reactions, bronchospasm, and respiratory depression, according to the drug label. It has been suspected in the literature that cross-allergy may occur between pholcodine and certain muscle relaxants such as suxamethonium due to structural similarities (e.g., Florvaag, Johansson, 2009). However, in 2011, the European Medicines Agency (EMA) concluded that the data were insufficient and that there was insufficient evidence to support these assumptions.
