Human cationic antimicrobial protein-18 (hCAP-18) precursor and its synthetic derivative SAAP-148 — a next-generation 24-amino-acid cathelicidin-based peptide with broad-spectrum bactericidal activity against multidrug-resistant ESKAPE pathogens including MRSA biofilms, superior potency to its parent fragment LL-37, and retained efficacy under physiological salt and plasma conditions
Written by Michael Carroll — Owner, Director of Research · Reviewed by the Peptide Initiative Research Team · Editorial standards
Topical application (primary research route)
Route
1 recommended
Sites
Once daily
Frequency
Preparation
Cathelicidin (hCAP-18 / Synthetic Derivatives) in its prescribed form
Clean, dry storage container
Measuring device if applicable (oral syringe, measuring cup)
Calendar or reminder app for dosing schedule
Pro tip
Prepare all supplies on a clean surface before you begin. Having everything ready makes the process smoother and more sterile.
Mixing
Example calculation
Cathelicidin (hCAP-18 / Synthetic Derivatives) comes in pre-measured doses or forms. Follow the exact dosing instructions on your prescription label. No reconstitution or mixing is typically required for this formulation.
Dose calculation
Use Cathelicidin (hCAP-18 / Synthetic Derivatives) exactly as prescribed. Each unit contains the labeled amount. Your healthcare provider will determine the appropriate dose based on your individual needs and response.
Location
Site 01
Not applicable—this is not an injectable formulation
Follow your provider's instructions for this injection site. Rotate sites regularly to prevent tissue damage.
Rotate between 1 sites to prevent tissue buildup and ensure consistent absorption.
Pro tip
Rotate your injection sites with each dose to prevent lipohypertrophy (buildup of fatty tissue). Keep a simple log of where you last injected.
Step by step
Follow the specific administration instructions for your Cathelicidin (hCAP-18 / Synthetic Derivatives) formulation
Take or apply as directed by your healthcare provider
Store properly between uses according to package instructions
Pro tip
This peptide uses cathelicidin (hcap-18 / synthetic derivatives) is administered topical application (primary research route)—no injection required. Inject at a 90 degree angle into the muscle. Aspirate before injecting to ensure you haven't hit a blood vessel.
Timing
Optimal timing
Best time
Apply Cathelicidin (hCAP-18 / Synthetic Derivatives) to clean, dry skin. For best results, use consistently at the same time(s) each day. Evening application is often preferred to allow overnight absorption, unless otherwise directed.
With food?
As a topical product, Cathelicidin (hCAP-18 / Synthetic Derivatives) is not affected by food intake. Apply to clean skin and allow adequate absorption time before covering the area.
Stacking notes
Cathelicidin (hCAP-18 / Synthetic Derivatives) should be used as directed by your healthcare provider. If combining with other medications or supplements, discuss potential interactions with your provider. Avoid combining with compounds that have overlapping mechanisms unless specifically guided by a medical professional.
Sample daily schedule
As prescribed (once daily)
As prescribed by your healthcare provider injection
Site: Topical application (primary research route)—rotate sites if applicable
Maintain a consistent schedule for optimal results with Cathelicidin (hCAP-18 / Synthetic Derivatives). Set reminders if needed. If you miss a dose, follow your healthcare provider's instructions—do not double up on doses to compensate.
Dosing tiers
Dose
0.5 mg/mL drops (about 100 microliters per application)
Frequency
Twice daily
Duration
2 weeks
In a human phase 2a ear study, OP-145 drops at 0.5 mg per mL were applied to the affected ear twice daily for 2 weeks and were safe and well tolerated [4].
Preservation
Before mixing
Store Cathelicidin (hCAP-18 / Synthetic Derivatives) in the refrigerator at 36-46°F (2-8°C) in its original packaging. Protect from light and moisture. Do not freeze. Check the expiration date before use. Some formulations may be stored at room temperature for limited periods—check your specific product labeling.
After mixing
Once reconstituted, Cathelicidin (hCAP-18 / Synthetic Derivatives) should be kept refrigerated at 36-46°F (2-8°C) and used within the timeframe specified on your product labeling (typically 14-28 days). Label the vial with the reconstitution date. Do not use if the solution appears cloudy, discolored, or contains particles.
Shelf life after mixing
7 days refrigerated (reconstituted); lyophilized powder stable for 2+ years at -20°C
Signs of degradation
Discard the vial immediately if you notice any of these:
Solution appears cloudy, discolored, or contains visible particles (should be clear)
Product has been exposed to temperatures outside the recommended storage range
Product has been frozen (unless specifically designed for freeze-thaw stability)
Expiration date has passed or reconstituted solution has exceeded its use-by date
Unusual odor, color change, or visible contamination
Important
When to stop
Severe or worsening side effects that don't improve with dose adjustment or supportive care
Signs of an allergic reaction—rash, hives, swelling, or difficulty breathing
Your healthcare provider recommends discontinuation based on your clinical response
Development of any new medical condition that may be contraindicated with Cathelicidin (hCAP-18 / Synthetic Derivatives)
Pregnancy or planning to become pregnant (unless specifically approved for use during pregnancy)
Abnormal lab results or clinical markers that suggest adverse effects
Cathelicidin (hCAP-18 / Synthetic Derivatives) should only be started, adjusted, or discontinued under medical supervision. This information is for educational purposes only and does not replace professional medical advice. Never stop a prescribed treatment without consulting your healthcare provider first, as abrupt discontinuation may have consequences.
Clean technique checklist
Wash hands thoroughly with soap and water before handling supplies
Swab vial tops and injection site with alcohol and let dry
Never touch the needle tip or allow it to contact non-sterile surfaces
Use a new syringe and needle for each injection
Dispose of used sharps in a proper sharps container
Store reconstituted peptides according to the storage instructions above
Published research
Coorens M, Schneider VAF, de Groot AM, et al. · 2017
Cathelicidins kill harmful bacteria in an immunologically quiet way by punching holes in their cell membranes, while simultaneously binding to bacterial toxins to prevent dangerous immune reactions.
Dijksteel GS, Ulrich MMW, Middelkoop E · 2019
Research (2019) on cathelicidin contributes important scientific knowledge about its biological and pharmacological properties.
Ön A, Vejzovic D, Jennings J, et al. · 2023
Clinical trial (2020) provides evidence for cathelicidin's effectiveness in therapeutic management.
Peek NFAW, et al. · 2020
In a phase IIa trial, P60.4Ac (OP-145) ear drops at 0.5 mg/mL twice daily for 2 weeks gave treatment success in 47% of patients versus 6% with placebo.
Dzurová L, Holásková E, Pospíšilová H, et al. · 2024
Research (2004) demonstrates cathelicidin's potent antimicrobial activity and broad-spectrum effectiveness against pathogenic microorganisms.
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