Cathelicidin (hCAP-18 / Synthetic Derivatives) dosing & administration
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
Dosing
How much do I take?
Topical: Applied onto the skin as a cream, gel, or lotion — it works mainly where you put it.
Bioavailability Local — acts mainly at the skin; little reaches the bloodstream.
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].
Timing
Best time to take
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.
If stacking
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.
Adjusting your dose
Increase if
- You've tolerated the current dose for the recommended period without significant side effects
- Therapeutic goals haven't been met at the current dose level
- Your healthcare provider recommends dose escalation based on your response
- Lab work or clinical assessments support a higher dose
Decrease if
- Side effects are bothersome or impacting daily life despite management strategies
- You experience any signs of an adverse reaction
- Lab results indicate the need for dose reduction
- Your healthcare provider recommends a lower dose based on your response
Signs of right dose
- Therapeutic goals being met with minimal side effects
- Stable and consistent response to treatment
- Lab values or clinical markers trending in the right direction
- Good tolerance with manageable or absent side effects
Administration
How do I use it?
Reconstitution
What you need
Injection
Route
Cathelicidin (hCAP-18 / Synthetic Derivatives) is administered Topical application (primary research route)—no injection required
Best sites
Storage
Before reconstitution
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 reconstitution
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.
Signs of degradation — discard the vial
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.
Safety
Is it safe?
Side effects
Commonly reported: Local application site irritation, Local inflammatory response, Mild wound exudate increase
Less common: Localized urticaria, Transient pain at injection site
Stop and seek help if
- 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.
Flagged pairings
- High concentrations of divalent cations (Mg²⁺, Ca²⁺) in formulations — may reduce electrostatic membrane binding of cationic cathelicidin peptides — Use with caution—discuss with your healthcare provider.
- Anionic surfactants or high-concentration albumin solutions — may sequester cationic peptides and reduce bioavailability — Use with caution—discuss with your healthcare provider.
- Immunosuppressive medications without supervision — cathelicidin derivatives promote immune activation that may conflict with immunosuppressive goals — Use with caution—discuss with your healthcare provider.
Published research
What the studies show
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.
Head to head
Cathelicidin (hCAP-18 / Synthetic Derivatives) compared
Want the full picture?
The complete Cathelicidin (hCAP-18 / Synthetic Derivatives) research profile: mechanism of action, clinical studies, effectiveness timeline, and FAQ.