Peptide Profile
Defensin (HBD-3)
Most potent human beta-defensin (45 amino acids) with unique salt-insensitive antimicrobial activity — kills MRSA at MIC 0.5-1.0 μg/mL regardless of salt concentration, disrupts biofilms at 4-8 μg/mL, and retains full bactericidal function even without its disulfide bonds — representing a next-generation antimicrobial peptide template for combating antibiotic resistance
Dose Range
1-50μg/mL (research)
Frequency
As needed
Route
Topical application (research/wound care)
Cycle Length
Ongoing/indefinite
Onset
Rapid (hours to days)
Evidence
Moderate
Compound Profile
Scientific & Efficacy Data
Approximately C220H340N64O62S6 (45-amino acid peptide with 3 disulfide bonds)
Molecular Formula
~5,155 Da (mature peptide)
Molecular Weight
Short systemic half-life (minutes) typical of cationic peptides; disulfide-bonded form provides protease resistance at local tissue sites; linear form shows adequate stability for topical applications
Half-Life
Topical application achieves high local concentrations; maintains activity in physiological salt environments (unique); linear form retains activity enabling simplified formulation; not intended for oral or systemic delivery
Bioavailability
Not assigned (endogenous human peptide; research-grade available from peptide suppliers)
CAS #
Not assigned (protein/peptide; UniProt P81534)
PubChem Status
Developed By · 2001 (first isolation and characterization); 2003 (disulfide-independence discovery); 2010s (anti-biofilm and lipid II mechanism characterization)
Endogenous; developed by Microbiotix
Microbiotix Inc.
Primary Benefits
Amino Acid Sequence
GIINTLQKYYCRVRGGRCSTPSDVVIACPGSMYDPTANTVTYDYPDDosing
How much
do I take?
Starting Dose
1-5 μg/mL topical or research application
Effective antimicrobial concentration against MRSA at the low end of this range (MIC 0.5-1.0 μg/mL). HBD-3's extraordinary potency means low concentrations are sufficient for gram-positive coverage. All dosing reflects research and preclinical settings — no established clinical protocols exist for exogenous HBD-3 application.
Standard Dose
5-15 μg/mL topical application
Provides broad-spectrum antimicrobial coverage against gram-positive bacteria, gram-negative bacteria, and fungi. Covers MIC requirements for most target pathogens. Effective anti-biofilm activity begins at the higher end of this range. Full activity maintained regardless of wound fluid salt concentration.
Advanced Dose
15-50 μg/mL topical application
Provides robust anti-biofilm activity (MRSA biofilm disruption at 4-8 μg/mL) with significant margin above MICs for all major target pathogens. At these concentrations, combined antimicrobial killing, biofilm disruption, and immune cell chemotaxis are all maximally active. Monitor for any cytotoxicity at the high end — therapeutic window remains wide.
Timing
Best time to take
Apply Defensin (HBD-3) 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, Defensin (HBD-3) is not affected by food intake. Apply to clean skin and allow adequate absorption time before covering the area.
If stacking
Defensin (HBD-3) 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
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Suitability
Is this
right for me?
Best For
Research into anti-MRSA therapeutics and alternatives to vancomycin for resistant infections
Defensin (HBD-3) is particularly well-suited for individuals focused on research into anti-mrsa therapeutics and alternatives to vancomycin for resistant infections. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
Development of antimicrobial wound dressings and medical device coatings
Defensin (HBD-3) is particularly well-suited for individuals focused on development of antimicrobial wound dressings and medical device coatings. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
Anti-biofilm strategies for chronic wound infections and implant-associated infections
Defensin (HBD-3) is particularly well-suited for individuals focused on anti-biofilm strategies for chronic wound infections and implant-associated infections. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
Applications requiring antimicrobial activity in physiological or high-salt environments
Defensin (HBD-3) is particularly well-suited for individuals focused on applications requiring antimicrobial activity in physiological or high-salt environments. 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 defensin peptides or formulation components
- ×Pregnancy and breastfeeding — insufficient safety data for exogenous defensin administration
- ×Active autoimmune conditions — potential for immune activation through monocyte/macrophage recruitment
- ×Severe hepatic or renal impairment — peptide clearance may be altered for any systemic exposure
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 Defensin (HBD-3) use
- !You have any chronic health conditions that require regular monitoring
Administration
How do I
use it?
Reconstitution
What you need
- •Defensin (HBD-3) 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
Defensin (HBD-3) is administered Topical application (research/wound care)—no injection required
Best sites
- •Not applicable—this is not an injectable formulation
Technique
- 1.Follow the specific administration instructions for your Defensin (HBD-3) 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
Defensin HBD-3 is not FDA-approved and has no completed human clinical trials, existing only in research contexts with in vitro and animal study data. Animal toxicology studies demonstrate no major systemic toxicity at doses exceeding therapeutic levels, but human immunological responses to exogenously administered defensin peptides have not been characterized. Risks include potential immune activation, cross-reactivity with self-antigens (due to HBD-3 expression in healthy epithelial cells), development of anti-peptide antibodies, and possible tolerance development with repeated dosing. Bacterial and fungal resistance to defensin-based therapy is theoretically possible. No human pharmacokinetics, dose-ranging studies, Phase 1 safety assessments, or clinical efficacy data exist.
Evidence is limited to in vitro studies of antimicrobial activity, animal infection models demonstrating efficacy, and immunological studies using isolated cells. No human safety data, pharmacokinetics, or clinical trials of any phase have been conducted. Published research focuses exclusively on mechanism and animal proof-of-concept rather than safety characterization.
Common Side Effects
Experienced by some users
Local site irritation
Mild irritation, redness, or warmth at the topical application site, reflecting the peptide's potent immune activation and monocyte recruitment through CCR2.
Management: Generally self-limiting and expected. Monitor site and reduce concentration if irritation is excessive. The high cationic charge of HBD-3 can cause more pronounced local effects than HBD-2.
Transient inflammatory response
Local inflammatory response from CCR2-mediated monocyte/macrophage recruitment to the application site. More pronounced than other defensins due to HBD-3's potent immunomodulatory activity.
Management: Expected pharmacological effect. Document and monitor. Should remain localized and self-limiting.
Mild wound bed changes
Increased exudate or transient changes in wound bed appearance as biofilm disruption releases previously sequestered bacteria and debris.
Management: This may indicate successful biofilm disruption — the wound may appear temporarily worse before improving as biofilm is cleared. Use appropriate absorbent dressings.
Less Common
- •Localized allergic reaction
- •Mild cytotoxicity at high concentrations
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 Defensin (HBD-3)
- ×Pregnancy or planning to become pregnant (unless specifically approved for use during pregnancy)
- ×Abnormal lab results or clinical markers that suggest adverse effects
Defensin (HBD-3) 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
- !Anionic polymers or surfactants — may complex with the cationic HBD-3 and neutralize activity through electrostatic interactions - Use with caution—discuss with your healthcare provider.
- !High concentrations of divalent cations (Ca²⁺, Mg²⁺) in formulation — may affect peptide-membrane interactions at extreme concentrations - Use with caution—discuss with your healthcare provider.
- !Proteolytic wound debridement enzymes (collagenase) applied simultaneously — may degrade the peptide at the application site despite its relative protease resistance - Use with caution—discuss with your healthcare provider.
With supplements
- ✓Multivitamins - Generally safe to take alongside Defensin (HBD-3). 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
Minutes to hours (acute phase)
What you might notice
- •Rapid bactericidal activity — MRSA killing begins within minutes of contact at MIC concentrations
- •Biofilm disruption initiating at higher concentrations (4-8 μg/mL)
- •Mild local warmth or redness from monocyte recruitment via CCR2
- •Immediate antimicrobial effect regardless of wound fluid salt concentration
What's normal
- •HBD-3 acts rapidly — one of the fastest-acting human antimicrobial peptides
- •Activity is maintained in wound fluid, serum, or high-salt environments (unique advantage)
- •Biofilm disruption may release bacterial debris causing temporary increase in wound exudate
What's next
- →Continue application per research protocol
- →Monitor bacterial clearance through culture or molecular assays
- →Document any local tissue responses for safety assessment
Days 1-7 (research protocol)
What you might notice
- •Significant reduction in MRSA and other target pathogen burden at treatment site
- •Visible biofilm disruption and clearance in chronic wound models
- •Improved wound bed quality with healthier granulation tissue
- •Enhanced monocyte/macrophage infiltration supporting tissue repair
What's normal
- •Continued pathogen clearance with daily application
- •Wound appearance may temporarily worsen as biofilms are disrupted before improving
- •Local immune cell recruitment intensifies during the first week of treatment
What's next
- →Assess treatment efficacy through bacterial quantification and wound measurements
- →Consider combination with conventional antibiotics to exploit biofilm-disrupted bacteria
- →Adjust concentration based on observed response and pathogen sensitivity
Week 2-4 (extended research protocol)
What you might notice
- •Near-complete or complete eradication of target pathogens including resistant strains
- •Advanced wound healing with re-epithelialization in wound models
- •Resolution of chronic infection signs (odor, excessive exudate, poor granulation)
- •Stable wound bed without evidence of recurrent bacterial colonization
What's normal
- •HBD-3's multi-mechanism approach (killing + biofilm disruption + immune recruitment) provides comprehensive infection resolution
- •The salt-insensitive activity ensures consistent performance throughout the treatment course
- •Newly healed tissue should show healthy vascularization and epithelial coverage
What's next
- →Complete research protocol endpoints
- →Document efficacy data for potential clinical translation
- →Assess durability of antimicrobial effect after treatment cessation
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 Defensin (HBD-3) 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
"Isolation and characterization of human beta-defensin-3, a novel human inducible peptide antibiotic"
Harder J, Bartels J, Christophers E, Schröder JM, 2001
Finding: Research supports defensin-hbd-3's antimicrobial effectiveness against a broad range of pathogens with minimal human toxicity.
View Study"The role of human beta-defensin-3 in infection and immunity"
García JR, Jaumann F, Schulz S, Krause A, Rodríguez-Jiménez J, Forssmann U, Adermann K, Klüver E, Vogelmeier C, Becker D, Hedrich R, Forssmann WG, Bals R, 2001
Finding: Research (2001) on defensin hbd 3 contributes important scientific knowledge about its biological and pharmacological properties.
View Study"Engineering disulfide bridges to dissect antimicrobial and chemotactic activities of human beta-defensin 3"
Wu Z, Hoover DM, Yang D, Boulègue C, Santamaria F, Oppenheim JJ, Lubkowski J, Lu W, 2003
Finding: Research (2003) demonstrates defensin hbd 3's potent antimicrobial activity and broad-spectrum effectiveness against pathogenic microorganisms.
View Study"Human beta-defensin 3 inhibits cell wall biosynthesis in Staphylococci"
Sass V, Schneider T, Wilmes M, Körner C, Tossi A, Novber N, Schwarz S, Żyła DS, Global Alliance, Hoerauf A, 2010
Finding: Research (2010) on defensin hbd 3 contributes important scientific knowledge about its biological and pharmacological properties.
View Study"Anti-biofilm activity of human beta-defensin 3 against Staphylococcus aureus biofilms"
Zhu C, Tan H, Cheng T, Shen H, Shao J, Guo Y, Shi S, Zhang X, 2013
Finding: Study (2013) characterizes the biological activity and functional properties of defensin hbd 3.
View StudyFrequently Asked Questions