Upload
jim-mcelroy
View
338
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Antimicrobial Preservation Overview For Formulators and Process Scientists
Citation preview
ANTIMICROBIAL
PRESERVATION OVERVIEW
JIM MCELROY
THE BASICS
• THIS PRESENTATION IS FOR THE FORMULATION SCIENTIST THAT HAS LITTLE OR NO MICROBIOLOGY EXPERTISE
• IT IS ALSO AN INTRODUCTION TO BASIC PRESERVATIVE CHEMISTRY AND ACTION
COMPOSITION AND STRUCTURE OF MICROORGANISMSBACTERIA BASICALLY COME IN TWO TYPES:
• THOSE THAT HAVE A LOT OF PEPTOGLYCAN IN THEIR CELL WALLS AND THOSE THAT HAVE A LITTLE.
• WHEN BACTERIA ARE STAINED, IT IS DUE TO A CHEMICAL REACTION BETWEEN THE STAIN AND THE PEPTOGLYCAN. CRYSTAL VIOLET STAIN IS GRAM POSITIVE.
• SAFRANIN (WHICH IS RED) INDICATES GRAM NEGATIVE.
CELL MEMBRANES
• THE CELL ENVELOPE IS THE RATE LIMITING BARRIER FOR THE PARTITIONING OF :
• NUTRIENTS
• WASTE PRODUCTS
• CHEMICALS
• MAIN COMPONENTS ARE PHOSPHOLIPIDS AND PROTEINS
• MAJOR PROTEINS ARE HYDROPHOBIC
• THE PLASMA STRUCTURE IS STABILIZED BY HYDROGEN BONDING
• MG2+ AND CA2+ CATIONS STABILIZE THE MEMBRANE
COMPARISONProperty or Constituent Gram
PositiveGram Negative
1. Liposacharide Outer Layer Absent Present
2. Polysaccharide High Low
3. Lipids 2-4% 15% or more
4. Solubility of lipids in fat solvents
Resistant Less resistant
5. Amino Acids 3-4 Complete range
6. Optimal Growth pH Relatively high
Relatively low
7. Nature of toxin Exotoxin Endotoxin
YEAST AND MOLD• YEAST: CELL WALL IS COMPOSED OF TWO OR MORE
PROTEIN POLYSACHARIDE COMPLEXES HELD TOGETHER BY COVALENT BONDS
• YEAST: MANNAN IS A CELL WALL COMPONENT
• MOLD: CELL WALL IS COMPOSED OF TWO OR MORE PROTEIN POLYSACCHARIDE COMPLEXES HELD TOGETHER BY COVALENT BONDS
• MOLD: MANNAN IS NOT A CELL WALL COMPONENT
COMPARISON (BACTERIA, YEAST & MOLD)
Property Bacteria Yeast, Mold
Cell size (μm) 0.5-5 Yeast 20-50Mold ≥100
Cell wall Teichoic acids, muramic acid peptides
Chitin, glucans, manans, and diaminopimelic acid
Cytoplasmic membrane
No sterols Sterols
Cytoplasm No mitochondria and endoplasmic reticulum
Mitochondria and endoplasmic reticulum
Nucleus Prokaryotic (no membrane) Eukaryotic (membrane)
WHAT IS A PRESERVATIVE?
A CHEMICAL SUBSTANCE THAT IS USED TO PRESERVE PHARMACEUTICALS, FOOD OR OTHER ORGANIC MATERIAL FROM DECOMPOSITION OR FERMENTATION BY PREVENTING THE GROWTH OF MICROORGANISMS.
COMMONLY USED PRESERVATIVES
INGESTIBLE & TOPICAL
• PARABENS
• SORBIC ACID
• NA, K & CA SORBATE
• BENZOIC ACID
• NA, K & CA BENZOATE
• SODIUM METABISULFITE
• PROPYLENE GLYCOL (15-30%)
• BHT, BHA
• FLAVORS W/ BENZALDEHYDE
TOPICAL ONLY
• FORMALDEHYDE DONORS
• ESSENTIAL OILS
•MONOGLYCERIDE
• PHENOL
•MERCURY COMPOUNDS
PARABENS
• PARABENS ARE AMONG THE MOST COMMONLY USED PRESERVATIVES.
• THEY ARE RELATIVELY ACTIVE AGAINST A BROAD SPECTRUM OF MICROORGANISMS.
• THE METHYL ESTER IS MOST EFFECTIVE AGAINST BACTERIA AND MOLDS
• THE ETHYL, PROPYL & BUTYL ESTERS ARE MORE ACTIVE AGAINST YEAST AND MOLDS.
• PARABENS ARE MORE EFFECTIVE AGAINST GRAM NEGATIVE THAN GRAM POSITIVE ORGANISMS.
• PARABENS DISASSOCIATE AT HIGH PH (8 OR MORE) AND ARE RENDERED INEFFECTIVE.
PARABENS HAVE LIMITED SOLUBILITY IN H2O
Property Methylparaben sol. g/100mg
Ethylparabensol. g/100mg
Propylparabensol. g/100mg
Butylparabensol.g/100mg
Water 18ºC 0.16 0.08 0.023 0.005
Water 25ºC 0.25 0.11 0.04 0.015
Water 80ºC 3.2 0.86 0.45 0.15
Ethanol 22 25 26 110
PG 1.7 0.5 0.4 0.3
Peanut Oil 0.5 1 1.4 5
Mineral Oil 0.01 0.025 0.03 0.1
PARTITION COEFFICIENTS AND EMULSIONS
PAY CLOSE ATTENTION TO PRESERVATIVE PARTITIONING IN EMULSION SYSTEMS. PARABENS PREFER THE OIL PHASE THUS LEAVING LITTLE IN THE WATER PHASE WHERE IT IS NEEDED.
Oil dropletWater phase
Surfactant
PARTITIONING OF PARABENS
• PARABENS ARE LIPOPHILIC.
• PARABENS WILL PARTITION DISPROPORTIONATELY INTO THE OIL PHASE OF AN EMULSION.
• IF LARGE AMOUNTS OF THE PRESERVATIVE PARTITION INTO THE OIL PHASE, IT IS NOT AVAILABLE FOR ANTIMICROBIAL ACTION.
PARTITION COEFFICIENT MEASUREMENT
• CW IS THE PRESERVATIVE LEFT IN THE WATER PHASE
• C IS OVERALL % OF PRESERVATIVE
• KW IS THE PARTITION COEFFICIENT
• Ά IS PHASE VOLUME RATIO
Cw=C* ά + 1 / Kw + 1
PARTITION COEFFICIENTS FOR PARABENS & OTHER PRESERVATIVESPreservative Kw Oil
Methylparaben 7.5 Almond Oil
0.1 Mineral Oil
18.0 Isopropyl Myristate
200 Diethyl Adipate
Ethylparaben 26.0 Soya Oil
Propylparaben 87.0 Soya Oil
Butylparaben 280.0 Soya Oil
Benzoic Acid 6.10 Soya Oil
Phenol 5.60 Arachis Oil
0.07 Mineral Oil
Sorbic Acid 3.3 Almond Oil
0.21 Mineral Oil
CHELATING AGENTS AS PRESERVATIVE ENHANCERS
ALKALINE EARTH METALS SUCH AS CA+ AND MG+ ARE IMPORTANT FOR THE STABILIZATION OF THE OUTER MEMBRANE OF CELLULAR ORGANISMS. CHELATING AGENTS SEQUESTER THESE IONS.
EDTA IS A TYPICAL CHELATING AGENT USED IN FORMULATIONS.
CHELATING AGENTS ARE NOT PRESERVATIVES
• PROVIDE A SYNERGISTIC EFFECT FOR THE OVERALL PRESERVATIVE SYSTEM
• CONTRIBUTE TO THE PARTIAL SOLUBILIZATION OF THE CELL MEMBRANE WHICH ALLOW PRESERVATIVES A PATHWAY INTO THE CELL.
INGREDIENTS THAT ENHANCE PRESERVATIVE EFFICACY
• SOLUTES (SALTS & HIGH CONCENTRATION OF SUGARS)
• ESTERS
• CATIONIC AND ANIONIC SURFACTANTS
• HUMECTANTS (GLYCERIN, PROPYLENE GLYCOL)
• PHENOLIC ANTIOXIDANTS (BHT)
• CHELATING AGENTS (EDTA)
• FRAGRANCES
• LOW WATER ACTIVITY
INGREDIENTS THAT HINDER PRESERVATIVE EFFICACY
• SUGARS AND ALCOHOL SUGARS
• PROTEINS, PEPTIDES, YEAST EXTRACT
• NATURAL GUMS & CELLULOSE THICKENERS
• PLANT EXTRACTS (ALOE VERA, STARCH,…)
• VITAMINS
• CLAY COMPOUNDS
• HIGH WATER ACTIVITY
• SURFACTANTS (TWEEN 80)
MANUFACTURING STEPS THAT ENHANCE PRESERVATIVE EFFICACY• SANITARY CONDITION OF EQUIPMENT
• TREATMENT OF RAW MATERIALS
• HEAT TREATMENT OF SUB-PHASE OR FINAL BATCH
• SUB-MICRON FILTRATION
• HOT FILL
• ASEPTIC FILL
PACKAGING COMPONENTS AND PRESERVATIVE EFFICACY
• DESIGN OF OPENING OR DISPENSER
• SUSCEPTIBILITY TO CONTAMINATION FROM ENVIRONMENT
• SUSCEPTIBILITY TO CONTAMINATION FROM HUMAN CONTACT
CONCLUSION
IT IS IMPORTANT TO TAKE INTO CONSIDERATION ALL ASPECTS OF THE FORMULA BEFORE CONSIDERING A PRESERVATIVE SYSTEM. THIS INCLUDES:
• TYPE OF FORMULA (TOPICAL OR INGESTED)
• WATER ACTIVITY
• ORGANISMS LIKELY TO PROLIFERATE
• BULK HANDLING
• PACKAGING.