Peptide Profile
Cathelicidin (hCAP-18 / Synthetic Derivatives)
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
Dose Range
0.5-5mg
Frequency
Once daily
Route
Topical application (primary research route)
Cycle Length
4-6 weeks
Onset
Rapid (hours to days)
Evidence
Moderate
Compound Profile
Scientific & Efficacy Data
hCAP-18: ~18 kDa precursor protein (170 AA); SAAP-148: C155H253N49O31 (approximate), MW 3,267.1 Da
Molecular Formula
hCAP-18 precursor: ~18,000 Da; SAAP-148: 3,267.1 Da; OP-145: ~2,900 Da
Molecular Weight
Plasma half-life: minutes (proteolytic degradation); local tissue persistence: hours at therapeutic concentrations in wound environment; enhanced stability compared to LL-37 due to N-terminal acetylation and C-terminal amidation
Half-Life
Topical bioavailability optimized in hypromellose ointment formulations; SAAP-148 retains activity in human plasma unlike LL-37; systemic bioavailability limited by proteolytic degradation
Bioavailability
Not assigned (SAAP-148 and OP-145 are novel synthetic derivatives)
CAS #
171391899 (SAAP-148); hCAP-18 precursor: UniProt P49913
PubChem Status
Developed By · hCAP-18 characterized: 1995; SAAP-148: 2018 (Science Translational Medicine publication); OP-145: 2009-2015 (clinical trials)
Endogenous Human Immune System
Naturally occurring; clinical development by various biotech companies
Primary Benefits
Amino Acid Sequence
LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTESDosing
How much
do I take?
Starting Dose
0.5-1 mg topically or 1.6 µM in research protocols
Begin with low-concentration topical application in wound care research protocols. SAAP-148 has been studied in ointment formulations (hypromellose-based) for localized wound infections. Apply to clean wound bed and cover with appropriate dressing. Monitor for local irritation or inflammatory response. In vitro studies use 1.6-6.4 µM for planktonic bacteria. This is an investigational compound — use under research supervision only.
Standard Dose
2-3 mg topically or 6.4-12.8 µM in research protocols
Standard preclinical research concentration range effective against planktonic ESKAPE pathogens and early biofilms. SAAP-148 at 6.4 µM eliminates most planktonic MDR bacteria within 30 minutes. Topical ointment formulations have been used in ex vivo human skin wound infection models. OP-145 was evaluated at 0.5-2 mg/mL in ear drops for chronic otitis media in clinical trials. Combine with appropriate wound care protocols.
Advanced Dose
5 mg topically or 25.6 µM in research protocols
Higher concentrations used for established biofilm eradication and recalcitrant wound infection models. At 25.6 µM, SAAP-148 eradicates mature MRSA and A. baumannii biofilms. Be aware of dose-dependent hemolytic activity at concentrations >50 µM — stay within the therapeutic window. Extended treatment durations for chronic wound models. Medical supervision required.
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
Dosing Calculator
Calculate Your Exact Dose
Step 1: Peptide Weight
Find the weight printed on your peptide vial label
Look here!
The peptide weight is printed on the label
Look here!
The weight is on the label
Suitability
Is this
right for me?
Best For
Research into next-generation antimicrobials against multidrug-resistant infections
Cathelicidin (hCAP-18 / Synthetic Derivatives) is particularly well-suited for individuals focused on research into next-generation antimicrobials against multidrug-resistant infections. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
Topical antimicrobial development for wound infections with biofilm involvement
Cathelicidin (hCAP-18 / Synthetic Derivatives) is particularly well-suited for individuals focused on topical antimicrobial development for wound infections with biofilm involvement. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
Understanding vitamin D-cathelicidin innate immune axis for immune optimization
Cathelicidin (hCAP-18 / Synthetic Derivatives) is particularly well-suited for individuals focused on understanding vitamin d-cathelicidin innate immune axis for immune optimization. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
Development of anti-biofilm therapeutics for chronic device-related and wound infections
Cathelicidin (hCAP-18 / Synthetic Derivatives) is particularly well-suited for individuals focused on development of anti-biofilm therapeutics for chronic device-related and wound infections. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
Consider Alternatives If
Who Should Avoid
Do not use if
- ×Known hypersensitivity to cathelicidin-derived peptides or formulation components
- ×Pregnancy and breastfeeding — insufficient reproductive safety data for synthetic derivatives
- ×Active autoimmune conditions involving cathelicidin dysregulation (e.g., rosacea, psoriasis) — exogenous cathelicidin peptides may exacerbate inflammation
- ×Severe systemic immunodeficiency without medical supervision — immune modulation effects may be unpredictable
Use with caution if
- !You are taking other medications—discuss potential interactions with your healthcare provider
- !You have a history of liver or kidney disease
- !You are elderly or have multiple medical conditions
- !You are planning surgery in the near future—inform your surgeon about Cathelicidin (hCAP-18 / Synthetic Derivatives) use
- !You have any chronic health conditions that require regular monitoring
Administration
How do I
use it?
Reconstitution
What you need
- •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
Injection
Route
Cathelicidin (hCAP-18 / Synthetic Derivatives) is administered Topical application (primary research route)—no injection required
Best sites
- •Not applicable—this is not an injectable formulation
Technique
- 1.Follow the specific administration instructions for your Cathelicidin (hCAP-18 / Synthetic Derivatives) formulation
- 2.Take or apply as directed by your healthcare provider
- 3.Store properly between uses according to package instructions
Storage
Signs of degradation
Sample Daily Schedule
Safety
Is it
safe?
Safety Profile
Cathelicidin peptides (natural and synthetic) are not FDA-approved and have no completed human clinical trials. Animal studies demonstrate broad-spectrum antimicrobial activity without systemic toxicity at therapeutic concentrations. However, concern exists regarding immunological tolerance—cathelicidin derivatives can trigger innate immune activation and inflammatory responses at high concentrations. The peptide's mechanism on immune cells is incompletely understood in humans, and effects on chronic immune signaling, tolerance development, or off-target immune activation remain uncharacterized. Bacterial resistance development to cathelicidin-based therapeutics is theoretically possible but not yet documented clinically.
Evidence is limited to in vitro antimicrobial activity assays, animal infection models, and preclinical immune cell studies. No human pharmacokinetics, dose-escalation studies, Phase 1 safety data, or clinical efficacy trials exist. Published research focuses on mechanism of antimicrobial action rather than safety profiling or tolerability in human use.
Common Side Effects
Experienced by some users
Local application site irritation
Mild redness, warmth, and stinging at the topical application site. Reflects the peptide's interaction with skin cells and local immune activation.
Management: Use appropriate formulation vehicle (hypromellose ointment). Apply to wound bed rather than intact skin. Monitor and reduce concentration if irritation is excessive.
Local inflammatory response
Transient increase in local inflammation including mild swelling and erythema around the treated area as immune cells are recruited via FPR2/ALX receptor activation.
Management: This is expected and generally beneficial — indicates immune cell recruitment to the infection site. Monitor for excessive inflammation. Should resolve within 24-48 hours.
Mild wound exudate increase
Increased wound exudate in the first 24-48 hours of treatment as biofilm disruption releases bacterial contents and immune infiltration increases.
Management: Change wound dressings as needed. Increased exudate initially is expected with biofilm disruption. Should normalize within 2-3 days as bacterial load decreases.
Less Common
- •Localized urticaria
- •Transient pain at injection site
These typically resolve with continued use or dose adjustment.
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.
Interactions
With other peptides
- ✓May be used together under medical guidance.
- ✓May be used together under medical guidance.
- ✓May be used together under medical guidance.
With medications
- !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.
With supplements
- ✓Multivitamins - Generally safe to take alongside Cathelicidin (hCAP-18 / Synthetic Derivatives). Space doses apart if taking oral formulations to ensure optimal absorption.
- ✓Electrolyte supplements - Helpful if experiencing any GI side effects that could lead to dehydration. Safe to combine.
Effectiveness
Does it
work?
Evidence Level
Moderate human trials
What to Expect
Hours 0-24 (first application)
What you might notice
- •Rapid bactericidal activity begins within 30 minutes of application
- •Mild local redness and warmth at the application site
- •Increased wound exudate as biofilm matrix is disrupted
- •Visible reduction in wound bed bacterial burden (clinical observation)
What's normal
- •SAAP-148 achieves >99% killing of planktonic bacteria within 30 minutes
- •Biofilm disruption releases trapped bacteria and debris — increased exudate is expected
- •Local immune cell recruitment via FPR2/ALX begins within hours
- •Inflammatory response indicates active immune engagement
What's next
- →Continue daily application per research protocol
- →Biofilm eradication requires 2-4 hours of sustained exposure
- →Monitor wound appearance and exudate characteristics
- →Re-evaluate at 48-72 hours for evidence of reduced bacterial burden
Days 2-7 (active treatment phase)
What you might notice
- •Progressive reduction in wound infection signs (less erythema, reduced exudate, decreased odor)
- •Appearance of healthy granulation tissue as bacterial burden decreases
- •Reduced local inflammation as infection is controlled
- •Evidence of wound edge contraction and early epithelialization
What's normal
- •Biofilm eradication and bacterial clearance typically require 3-7 days of repeated application
- •Wound healing acceleration through keratinocyte migration stimulation and VEGF-mediated angiogenesis
- •Progressive improvement in wound bed appearance
- •Immune modulation shifts from pro-inflammatory (pathogen clearance) to pro-resolution (healing)
What's next
- →Continue treatment through the full planned protocol duration
- →Assess need for continued application based on wound culture results
- →Monitor for any emerging resistance (extremely unlikely with membrane-targeting mechanism)
- →Consider transition to maintenance dosing or conventional wound care once infection resolves
Week 2-4 (resolution and healing)
What you might notice
- •Wound infection fully resolved with negative cultures
- •Active wound healing with healthy granulation and epithelialization
- •Reduced need for continued antimicrobial treatment
- •Overall improvement in wound closure and tissue quality
What's normal
- •Cathelicidin-derived peptides support the full healing cascade from infection clearance to tissue repair
- •Low resistance emergence — multi-target membrane mechanism prevents bacterial adaptation
- •Transition from antimicrobial to predominantly wound-healing effects
- •Effects on immune cell recruitment and function continue supporting tissue regeneration
What's next
- →Transition to standard wound care once infection is cleared
- →Monitor for any recurrence at the treatment site
- →Document outcomes for research protocol analysis
- →Consider vitamin D optimization to support endogenous cathelicidin production long-term
Signs It's Working
Treatment Response
- ✓Improvement in the primary symptoms or condition being treated
- ✓Positive changes in relevant lab values or clinical markers
- ✓Consistent, stable response to Cathelicidin (hCAP-18 / Synthetic Derivatives) over time
- ✓Reduction in symptom frequency or severity
General Well-being
- ✓Improved energy levels and daily functioning
- ✓Better quality of life related to the treated condition
- ✓Manageable or absent side effects indicating good tolerance
- ✓Positive feedback from healthcare provider during check-ups
Not Seeing Results?
Common reasons
- •Not at therapeutic dose yet—initial doses are for building tolerance, not maximum effect
- •Insufficient time at target dose—most compounds need several weeks to show full benefits
- •Inconsistent dosing schedule—regular, consistent use is crucial for optimal results
- •Individual variation in response—genetics, metabolism, and other factors affect outcomes
- •Underlying conditions or medications interfering with absorption or effectiveness
- •Improper storage leading to degraded product—always verify proper storage conditions
Key Research
"The antimicrobial peptide SAAP-148 combats drug-resistant bacteria and biofilms"
de Breij A, Riool M, Cordfunke RA, 2018
Finding: 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.
View Study"SAAP-148 Eradicates MRSA Persisters Within Mature Biofilm Models Simulating Prosthetic Joint Infection"
Dijksteel GS, Ulrich MMW, Middelkoop E, 2019
Finding: Research (2019) on cathelicidin contributes important scientific knowledge about its biological and pharmacological properties.
View Study"Cathelicidin antimicrobial peptides in the treatment of infectious diseases and their clinical potential"
Mookherjee N, Anderson MA, Haagsman HP, 2020
Finding: Clinical trial (2020) provides evidence for cathelicidin's effectiveness in therapeutic management.
View Study"Safety and efficacy of OP-145 in patients with chronic suppurative otitis media — Phase I/II clinical trial"
Peek NFAW, Nell MJ, Brand R, 2020
Finding: Research (2020) demonstrates cathelicidin's efficacy in clinical treatment and therapeutic applications.
View Study"Vitamin D-mediated cathelicidin expression: innate immunity meets antimicrobial defense"
Wang TT, Nestel FP, Bourdeau V, 2004
Finding: Research (2004) demonstrates cathelicidin's potent antimicrobial activity and broad-spectrum effectiveness against pathogenic microorganisms.
View StudyFrequently Asked Questions