Histaverin (Codeine Phosphate Sesquihydrate)

Histaverin is indicated for the symptomatic relief of conditions where mild to moderate pain or cough suppression is required.

• Mild to moderate acute pain such as dental, musculoskeletal, or postoperative discomfort.
• Cough associated with upper respiratory tract infections when a central antitussive effect is desired.
• Pain relief in patients who may not tolerate non‑opioid analgesics.
• Adjunct therapy for short‑term management of pain in palliative care settings.
• Temporary relief of headache or migraine symptoms when other treatments are insufficient.
• Management of discomfort related to minor injuries such as sprains or strains.

• Codeine phosphate sesquihydrate exerts its pharmacologic action primarily as an agonist at the μ‑opioid receptors in the central nervous system. By binding to these G‑protein‑coupled receptors, it inhibits the release of neurotransmitters involved in pain transmission, thereby raising the pain threshold. In addition, activation of μ‑receptors in the medullary cough centre reduces the cough reflex, providing antitussive activity. Metabolism of codeine produces a small amount of morphine, which contributes to its analgesic effect.

Like other opioid‑containing medicines, Histaverin may cause a range of adverse reactions, most of which are dose‑related and reversible. These effects are generally mild at therapeutic doses, but they can become more pronounced if the medication is taken in excess or combined with other central nervous system depressants. Patients should report any unexpected or severe symptoms to a healthcare professional promptly. In rare cases, the drug may cause visual disturbances or urinary retention.

Common

• Nausea or vomiting.
• Constipation.
• Drowsiness or mild sedation.

Serious

• Respiratory depression, particularly at high doses.
• Severe allergic reactions (rash, itching, swelling).
• Dependence or withdrawal symptoms with prolonged use.

When using Histaverin, certain precautions should be observed to minimize risks and ensure safe therapy.

• Assess patient history for respiratory disorders, such as asthma or chronic obstructive pulmonary disease.
• Avoid use in individuals with known hypersensitivity to codeine or other opioids.
• Use caution in patients with hepatic or renal impairment, as metabolism and excretion may be altered.
• Do not combine with other central nervous system depressants, including alcohol, benzodiazepines, or antihistamines, without medical guidance.
• Monitor for signs of dependence, especially during prolonged therapy.
• Pregnant or breastfeeding women should only use under strict medical supervision.

Histaverin can interact with several medicines, potentially altering its effects or increasing the risk of adverse reactions.

Avoid

• Concomitant use with other opioid analgesics or strong central nervous system depressants (e.g., benzodiazepines, barbiturates, alcohol).
• Monoamine oxidase inhibitors (MAOIs) taken within 14 days, due to risk of severe respiratory depression.
• CYP2D6 inhibitors (e.g., fluoxetine, paroxetine) that may increase codeine plasma levels.

Use with caution

• Sedating antihistamines or antipsychotics, which may enhance drowsiness.
• CNS‑active antidepressants (e.g., tricyclics) that could increase sedation.
• Medications that affect hepatic metabolism (e.g., rifampin) may reduce efficacy.
• Drugs that prolong QT interval, such as certain antiarrhythmics, should be used cautiously.