Overview
DESCRIPTION The chemical formula for Histamine Phosphate is C 5 H 9 N 3 · 2H 3 PO 4 ; its molecular weight is 307.14. For prick, puncture or scratch testing, the product is a sterile solution that contains 1 mg/mL histamine base (2.75 mg/mL Histamine Phosphate) in Water for Injection; it also contains Glycerin 50% (v/v) as viscosity agent and Phenol 0.4% as preservative.
Mechanism of Action
CLINICAL PHARMACOLOGY Histamine acts as a potent vasodilator when released from mast cells during an allergic reaction. It is largely responsible for the immediate skin test reaction of a sensitive patient when challenged with an offending allergen. The effect of added Glycerin (50% v/v) to 1 mg/mL histamine base was studied by puncture testing using a bifurcated needle in twelve volunteer subjects. The mean sum of cross-diameters of the wheals was 13.25 mm (range 10-15 mm) for the non-glycerinated, and 12.54 mm (range 9-15 mm) for the glycerinated formulation. Sum of cross-diameters of erythema was 52.88 mm (range 23-92 mm) for the non-glycerinated, and 54.42 mm (range 19-87 mm) for the glycerinated formulation. These differences are not statistically significant.
Indications
- INDICATIONS AND USAGE For use as a positive control in evaluation of allergenic (immediate hypersensitivity or "Type I") skin testing.
Common Doses
- 1 mg
- 2.75 mg
- 0.1 mg
- 0.275 mg
Dosage
DOSAGE AND ADMINISTRATION Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. For Prick, Puncture and Scratch Testing Histamine base 1 mg/mL (Histamine Phosphate 2.75 mg/mL) should be used to give a reaction. (Refer to Interpretation Section.) Prick, Puncture or Scratch Test Techniques The skin in the test area should be cleansed with alcohol and air dried.
Contraindications
- CONTRAINDICATIONS Histamine should not be injected into individuals with hypotension, severe hypertension, severe cardiac, pulmonary, or renal disease. Not to be used for diagnosis of pheochromocytoma or to test the ability of the gastric mucosa to secrete hydrochloric acid.
Side Effects
- ADVERSE REACTIONS Local: Reactions such as wheal, erythema and localized pruritus are to be expected, but if very large (i.e. greater than 4+ as described dosage and administration) may be the first manifestation of a systemic reaction. Systemic: Following the injection of large doses of histamine, systemic reactions may include flushing, dizziness, headache, bronchial constriction, urticaria, asthma, marked hypertension or hypotension, abdominal cramps, vomiting, metallic taste, and local or generalized allergic manifestations (see also OVERDOSAGE ).
Interactions
- Drug Interactions Drugs can interfere with the performance of skin tests in general, and specifically with histamine 1 . Antihistamines: Response to histamine is suppressed by antihistamines. The length of suppression varies, and is dependent on individual patient, type of antihistamine and length of time the patient has been on antihistamines. The duration of this suppression may be as little as 24 hours (chlorpheniramine), and can be as long as 40 days (astemizole).