In the pharmaceutical industry, Promethazine Hydrochloride 25 mg is a versatile, first-generation phenothiazine derivative. As a pharmacist and manufacturer, I classify this as a “multi-functional antihistamine” because it possesses antihistaminic, sedative, antiemetic, and anticholinergic properties all in one molecule.

Primary Clinical Uses

• Allergic Reactions: Treatment of hay fever (allergic rhinitis), allergic conjunctivitis, and skin conditions like urticaria (hives) or angioedema.

• Motion Sickness: Highly effective for the prevention and treatment of nausea and vomiting associated with travel.

• Nausea and Vomiting: Used post-operatively or in cases of severe gastroenteritis to control emesis.

• Sedation: Frequently used as a pre-operative sedative to relieve apprehension and induce light sleep, or for short-term management of insomnia.

• Adjunctive Analgesia: It is often combined with opioids (like Codeine) because it enhances the pain-relieving effect while counteracting the nausea often caused by those drugs.

Mechanism of Action: Multi-Receptor Antagonism

Promethazine is a “dirty drug” in pharmacological terms, meaning it acts on several different receptors, which accounts for its wide range of uses.

H1-Receptor Antagonism: It competes with free histamine for $H_1$-receptor sites. By blocking these, it stops the swelling, itching, and redness of an allergic response.

Blood-Brain Barrier: Because it is highly lipophilic, it crosses the blood-brain barrier easily, leading to significant sedation and its anti-motion sickness effect.

Anticholinergic Action: It blocks muscarinic receptors, which helps “dry up” secretions in the respiratory tract and reduces the signals from the inner ear to the brain that cause motion sickness.

Dopaminergic Blockade: In the Chemoreceptor Trigger Zone (CTZ), it weakly blocks dopamine receptors, contributing to its anti-nausea profile.

The Manufacturer’s Perspective: Formulation & Export

From a production and global trade standpoint at your WHO-GMP facility in Mumbai, Promethazine 25 mg involves several technical considerations:

• Photosensitivity: Promethazine is notoriously light-sensitive and can undergo oxidative degradation. At our facility, we utilize Amber-colored PVC/PVDC or Alu-Alu blister packaging to ensure a 36-month shelf life.

• The “Phenergan” Standard: In most B2B export markets (especially the UK, Africa, and SE Asia), the 25 mg tablet is the benchmark. Marketing your product as “Phenergan-equivalent” in your digital catalog is a major strategy for international trade.

• Pediatric Warning (Technical Compliance): As a pharmacist, you must ensure your Product Information Leaflet (PIL) includes the strict warning against use in children under 2 years of age due to the risk of potentially fatal respiratory depression—a critical regulatory requirement for export.

• Dossier Support: This is an essential medicine for hospital supply chains. We provide full CTD/eCTD Dossiers to help you participate in international tenders and pharmacy registrations.