PRE-PEN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PRE-PEN (PRE-PEN).
Benzylpenicilloyl polylysine is a skin test reagent that elicits a wheal-and-flare response in penicillin-allergic individuals by binding to penicillin-specific IgE antibodies on mast cells, triggering histamine release.
| Metabolism | Not metabolized; eliminated via proteolytic degradation. |
| Excretion | Primarily renal excretion (60-80% as unchanged drug and metabolites). Biliary/fecal elimination accounts for <10%. |
| Half-life | Terminal elimination half-life: 0.5-1.0 hour in patients with normal renal function. Clinical context: Rapid elimination allows for short duration of action; half-life is prolonged in renal impairment. |
| Protein binding | ~65% bound to serum proteins (primarily albumin). |
| Volume of Distribution | ~0.3-0.4 L/kg, indicating distribution primarily into extracellular fluid. |
| Bioavailability | Intradermal: 100% (local administration). Oral: not applicable (administered via intradermal injection only). |
| Onset of Action | Intradermal injection: 15-20 minutes for wheal-and-flare reaction. |
| Duration of Action | Intradermal: 30-60 minutes for immediate hypersensitivity reaction. Clinical note: Duration of skin test reactivity is brief; delayed reactions are not assessed. |
0.25 mL intradermal injection of a 1:100 dilution (0.25 mg/mL) for skin testing; if negative, proceed to 0.05 mL intradermal injection of 1:10 dilution (2.5 mg/mL).
| Dosage form | INJECTABLE |
| Renal impairment | No specific renal dose adjustment required; drug is not systemically absorbed. |
| Liver impairment | No specific hepatic dose adjustment required; drug is not systemically absorbed. |
| Pediatric use | Same as adult dosing: 0.25 mL intradermal of 1:100 dilution, then 0.05 mL of 1:10 dilution if negative. |
| Geriatric use | No specific geriatric dose adjustment; use same dosing as adults. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PRE-PEN (PRE-PEN).
| Breastfeeding | Not known whether benzylpenicilloyl polylysine is excreted in human milk. Caution advised. M/P ratio: unknown. |
| Teratogenic Risk | Pregnancy Category B. No evidence of teratogenicity in animal studies; insufficient human data. Risk cannot be ruled out; use only if clearly needed. |
| Fetal Monitoring | Monitor for signs of immediate hypersensitivity (e.g., urticaria, angioedema, anaphylaxis). Fetal monitoring if anaphylaxis occurs. |
■ FDA Black Box Warning
WARNING: ANAPHYLAXIS. Pre-Pen may cause anaphylaxis. Epinephrine should be immediately available. Patients with positive skin tests are at risk for immediate systemic allergic reactions. Administer only by personnel trained in emergency management of anaphylaxis.
| Serious Effects |
["History of anaphylaxis to penicillin.","Known hypersensitivity to benzylpenicilloyl polylysine."]
| Precautions | ["Anaphylaxis risk: immediate epinephrine availability required.","Systemic allergic reactions including serum sickness and Stevens-Johnson syndrome.","Cross-reactivity with cephalosporins and carbapenems.","False-positive results due to dermatographism or active infection.","Use with caution in patients with history of multiple drug allergies."] |
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| Fertility Effects | No known adverse effects on fertility from animal studies. No human data. |