histamine dihydrochloride: clinical use

Prescribing considerations

• Injectable treatment must be initiated and supervised by a clinician experienced in acute myeloid leukaemia and used with interleukin-2.
• Assess cardiovascular status and review hypotensive, cardiotoxic and histamine-blocking medicines.
• Use caution with significant renal or hepatic impairment, recent stroke, symptomatic peripheral arterial disease, bleeding gastrointestinal disease, active or recently treated infection, and autoimmune disease.
• For skin-prick testing, use healthy, lesion-free skin and consider postponement if skin disease or poor general health could make interpretation unreliable.
• The injectable product is subject to additional monitoring.

Contraindications and cautions

• Injection: hypersensitivity, significantly compromised cardiac function, systemic corticosteroid treatment, clonidine, H2-receptor antagonists, previous allogeneic stem-cell transplant, pregnancy or breastfeeding.
• Skin-prick control: hypersensitivity to an excipient.

Monitoring

• Monitor blood pressure, pulse and respiratory status during initial injectable treatment and while clinically significant changes persist.
• Monitor standard haematology and blood chemistry; assess for infection, hypotension and treatment toxicity.
• Evaluate ventricular function in patients with cardiac disease.
• Before interpreting allergen results, confirm an appropriate positive-control response and no nonspecific negative-control response.

Clinical pharmacology

Histamine dihydrochloride inhibits phagocyte NADPH oxidase and reduces reactive oxygen species, protecting interleukin-2-activated natural killer and T cells. After subcutaneous administration, it is rapidly absorbed and metabolised mainly through histamine-N-methyltransferase and diamine oxidase. Applied epicutaneously, it produces a local wheal-and-flare response.

Formulation and product differences

• The oncology product is a clear, colourless solution for slow subcutaneous injection in single-use vials.
• The allergy-testing product is a ready-to-use clear solution supplied with a histamine positive control and an active-ingredient-free negative control.
• The skin-prick preparation contains phenol, glycerol, phosphate salts and sodium chloride; the injection has a simpler sodium chloride and water-based formulation.

Injection

Route: Parenteral

Strengths: 0.5 mg/0.5 mL