2_19aug24 Sterile and eye products LESSON.pdf

Sterile and eye products 19 August 2024 1  Learning Objectives Principle of sterility and sterility assurance Manufacturing of sterile products Principles of eye administration Pollev.com/camben...

Sterile and eye products 19 August 2024 1  Learning Objectives Principle of sterility and sterility assurance Manufacturing of sterile products Principles of eye administration Pollev.com/camben 2 Sterility Sterility can be defined (WHO guidelines) as absence of viable microorganisms. However, the conditions that guarantee absolute sterility are usually too harsh for active ingredients, and the definition of sterility for a medicinal product must be defined in functional terms. Sterility relies on procedural measures that effectively prevent contamination of biological materials, such as clean room technology and other Good Manufacturing Practices. The Sterility Assurance Level (Sterility Assurance Level) indicates the probability of one viable microorganism in a certain number of drug products. It defines an acceptable safety level acceptable according to pharmacopeial standards. -1log (=10-1) is the probability of finding 1 microorganisms out of 10 loads of single containers -2log = (=10-2) is the probability of finding 1 microorganisms out of 100 loads of single containers -3log = (=10-3) is the probability of finding 1 microorganisms out of 1000 loads of single containers -6log = (=10-6) is the probability of finding 1 microorganisms out of 1 million loads of single containers 3 Sterility is a general requirement for: - Parenteral preparations - Eye preparations (ophthalmics) - Preparations for irrigation Raw materials and equipment are separately sterilized to avoid contamination (microrganisms and contaminants) sterility is difficult to achieve and takes a while to optimise Main critical factors Requirement for a sterile product Bioburden Without microorganisms People/PPE Endotoxins inside limits Air and surface quality No detectable particles Raw materials Equipment Preparation/cleaning/sterilization Filling and closure Exposure time 4 Sterility Assurance Level (SAL) Sterility test Endotoxin is a lipopolysaccharide (LPS) found in the outer membrane of gram negative bacteria Endotoxins test Bioburden Particulate contamination of injections and parenteral infusions consists of extraneous, mobile and undissolved particles, other than gas bubbles, unintentionally present in the solutions Visible/non-visible particles Pyrogens Pyrogens are substances that can produce a fever The most common pyrogens are endotoxins, which are lipopolysaccharides (LPS) produced by Gram-negative bacteria such as E. coli. 5 How to ensure sterility? Terminal sterilization Aseptic processing - Use of a lethal treatment on - Removal or separation of microorganisms (heat, radiation, microorganisms chemical) VS - Higher risk of contamination - Method of choice - More variables in the process and - Relatively easy to reproduce and harder to control validate - Fewer issues with materials - Not for all materials every step of the process is monitored for bioburden may be used for medical devices and secondary packaging 6 Sterilization methods overview Sterilization Method Specifications Advantages Disadvantages Dry heat 180 °C for 30 min Destroys pyrogens Heat sensitivity 170 °C for 1 hr 160 °C for 2 hr Moist heat Temperature: 121 °C Uses biological indicator to Heat/moisture Autoclave, gravity sterilizer Time: 15 min verify sufficient sensitivity heat/pressure Aseptic filtration Numerous fiber/size and Filter integrity test, verifies Filter must be certified for load specifications filter did not rupture volume and filtrate load Gamma irradiation Requires very high radiation Containers and packaging Not good for some heat to be effective may remain intact sensitive Ethylene oxide/nitrous Depending on gas used Less invasive, good for heat Requires tight wrap to avoid oxide, hydrogen peroxide different saturation and sensitive but has leaks, contaminates adjacent fog permeation compatibility issues areas Lyophilization Multi-step process Ease of processing a liquid Expensive Stability Require sterile diluent 7 Moist/Dry heat sterilization The basic principle of sterilization is to expose each item to the required temperature and pressure for the specified time Heat destroys microorganisms by the irreversible coagulation and denaturation of enzymes and structural proteins Aseptic filtration Aseptic (sterile) filtration is performed using 0.22 µm filter This method can be applied to thermolable objects and it can be used to remove pyrogens Non-sterile preparation Sterile filtrate Certain products that cannot be sterilized in the final container can be filtered through a sterile filter of nominal pore size 0.22 micron (or less) into a previously sterilized container Gamma radiation Sterilization by ionizing radiation, primarily by cobalt 60 or cesium 137 or electron accelerators, is a low-temperature sterilization that ensure low penetration (and high dose rate) and has been used mostly medical products and packaging materials usually used for medical devices; not a lot of materials are compatible Some deleterious effects on patient-care equipment associated with gamma radiation include induced oxidation in polyethylene and delamination and cracking in polyethylene knee bearings Chemical sterilization high temp not required Many heat-sensitive medical devices and surgical supplies can be effectively sterilized by liquid sterilants in “cold” systems (≈60o C) using ethylene oxide, formaldehyde, hydrogen peroxide and peracetic acid most common; may leave some residue Ethylene (ETO) oxide is an alkylating agent Peracetic acid is a highly biocidal oxidizer that maintains its efficacy in the presence of organic material It is mostly used for endoscopic tubes Gas plasmas (H2O2) are generated in an enclosed chamber under deep vacuum using radio frequency or microwave energy to excite the gas molecules and produce charged particles, many of which are in the form of free radicals 11  Lyophilization Lyophilization or freeze drying is a process in which water is removed from a product after it is frozen and placed under a vacuum, allowing the ice to change directly from solid to vapor without passing through a liquid phase easily redispersed w water or saline The process consists of three separate and interdependent processes: freezing primary drying (sublimation) secondary drying (desorption) Quick freezing of a small volume; Drying under vacuum; Desorption of water under vacuum; Crystals size may affect the final Aqueous vapour removal; End point = water content < 1% product. End point = temperature rising 12 Lyophilization 13 Sterile powder A drug in powdered form is necessary when the drug is unstable as a liquid form The powdered drug must be reconstituted with a sterile diluent before administration Multi-Dose Vials (MDVS) Can be used multiple times, for multiple doses Can retain sterility after needle puncture Usually contain preservatives some preservative is required to ensure product stays sterile for a period of time Remainder in vial must be stored properly and used before expiration date IV bags long term; slow flowing base solutions + medication dilution before administration 14 Patient-Controlled Analgesia An IV pain medication (usually opioids in combination) administered via device Continuous administration or button operated Devices are calibrated to prevent overdose 15 Epidurals Inserted intrathecally for pain control in surgery or obstetrics Consist of anesthetic (bupivacaine, ropivacaine), alone or with a narcotic All medication must be preservative-free, because they can cause paralysis Ophthalmics Prepared using aseptic filtration technique before being packaged in dropper bottle Instilled onto the external surface of the eye (topical), administered inside the eye (intraocular) or adjacent to it (periocular) 16 Nanosuspension for i.v. Jan Möschwitzer, Georg Achleitner, Herbert Pomper, Rainer H. Müller, Development of an intravenously injectable chemically stable aqueous omeprazole formulation using nanosuspension technology, European Journal of Pharmaceutics and Biopharmaceutics, Volume 58, Issue 3, 2004, Pages 615-619, ISSN 0939-6411, https://doi.org/10.1016/j.ejpb.2004.03.022. Omeprazole is a proton pump inhibitor difficult drug to work with: Lipophilic, weak base with a very low water solubility Sensitive to low pH value and to warm temperature What is the issue with this substance in preparing an i.v. injection? Low solubility Possible soultions: - in-situ salification - amorpheus solid dispersion - organic solvent (very limited feasibility) Administered as nanodispersion with sodium carbonate and Poloxamer synthetic polymer Definition of nanosuspension and role of the excipients? Carbonate as buffering agent and poloxamer as stabiliser 17 Crystal characteristics Polymorphs with varying solubility values Metastable polymorph has a higher solubility value than the stable polymorph Polymorphism and thus changes in solubility characteristics upon storage at a constant environment e.g. relative humidity, light, temperature, mechanical stress, or changing environmental conditions Solvate / hydrate – decreases or increases the solubility vs time effect Generally, hydrated crystal is less soluble in water than anhydrous counterpart due to stronger intermolecular bonding and reduced energy liberation Amorphous structure has a higher solubility than that of crystallite due to reduced lattice energy 18 Amorphous Solid Dispersion The solubility of the drug substance is improved by disarranging its crystalline lattice to produce a higher energy state of amorphous form Polymers play a key role to improve the solubility and bioavailability of amorphous API by drug polymer interaction 19  Particle size analysis via laser diffractometry Dispersion vs solution. Effect on drug stability? Drug as solid is more stable that drug in solution Dispersion is more chemically stable (less interaction to water and more resistant to change in temperature) Dispersion may not be physically stable (flocculated or non-flocculated system?) Effect of particle size on stokes law? Smaller the particle, the higher the sedimentation rate, the faster (?) Larger particle, the fall rate increases (?) Sodium carbonate and omeprazole sodium possible interaction? Common ion effect Which one of the following is the best way to manufacture this formulation? Aseptic manufacturing or aseptic filtration are both viable options Dispersion vs solution Effect on drug stability? Drug as solid is more stable than drug in solution Sodium carbonate and omeprazole sodium Possible interaction? Common ion effect Highly concentrated nanosuspension, chemically stable and protected from degradation 20 Eye anatomy Iris, the colored area of your eye Cornea, a clear layer that extends over the iris. Water and collagen make up the cornea. Your tears protect your cornea and keep it lubricated Pupil, the black circle which is an opening or window in the middle of your iris. It expands and contracts to control how much light gets into your eye The sclera, the white parts of your eye that surround the iris Conjunctiva, a clear, thin tissue that covers the sclera and lines the inside of your eyelids Lens, which sits behind the pupil. It focuses the light that comes into your eye and sends light to the back of your eye Retina, a collection of cells that line the inside of the back of your eye Macula, a small area that’s part of the retina. It’s responsible for central vision and helping you see fine details and color Optic nerve, which is behind the retina Muscles, which control your eye’s position and movement Vitreous, a transparent gel that fills your entire eye. It protects and maintains the shape of the eye 21 Eye anatomy The structure of eye can be divided into two main parts: anterior segment and posterior segment Anterior segment of the eye occupies approximately one-third while the remaining portion is occupied by the posterior segment Tissues such as cornea, conjunctiva, aqueous humor, iris, ciliary body and lens make up the anterior portion. Back of the eye or posterior segment of the eye include sclera, choroid, retinal pigment epithelium, neural retina, optic nerve and vitreous humor Ocular bioavailability is very low with topical drop administration 22 Eye administration most ocular medications are delivered topically - maximizes anterior segment concentrations and minimizes systemic toxicity Eye drops drug gradient from tear reservoir to corneal and conjunctival epithelium forces passive absorption drug concentration (limited by tonicity) and solubility (aqueous solution vs suspension) viscosity (increased residence time) lipid solubility: lipid rich epithelial cell membrane vs water rich stroma pH and ionic charge - most eye drops are weak bases existing in both charged and uncharged forms enhancing absorption Do you think you can use a surfactant in this case? No. Surfactant will not help you keep the eye drop in contact with the eye for a longer time. 23 Most common issue with eye administration? Reflex tearing: ocular irritation and secondary tearing wash out of the drug reservoir in the tears and reduce contact time with cornea This occurs when drops are not isotonic, have non-physiological pH or contain irritants Tissue binding: proteins in the tears and on the ocular surface may bind drug making the drug unavailable or creating a slow release reservoir This may affect peak effect and duration of action as well as delayed local toxicity 24  increases contact time of drug with ocular surface Eye ointments mixture of petrolatum and mineral oil water-soluble drugs are not soluble in the ointment and are present as microcrystals Surface microcrystals dissolve in the tears, the rest are trapped until the ointment melts poor solubility in water and high solubility in lipid Only drugs with high lipid solubility and some water solubility will get into both tears and corneal epithelium eg. chloramphenicol and tetracycline both achieve higher aqueous levels as ointment rather than drops Allow drugs to bypass the conjunctival/corneal epithelial barrier and reach therapeutic levels in the posterior segment anaesthetic agents, steroids, botulinum toxin 25  allow instant drug delivery at therapeutic concentrations to target site Intraocular injections intracameral eg. antibiotics intravitreal eg. avastin Drug getting into eye from systemic circulation limited by tight junctions in vascular endothelium of retinal vessels, and non-pigmented epithelium of ciliary body Drugs with higher lipid solubility pass through blood-ocular barrier more readily The extent of drug bound to plasma proteins also effects access of drug into eye - only unbound form can pass blood-ocular barrier: bolus administration exceeds the capacity of a drug to bind to plasma proteins and so leads to higher intraocular drug levels than with slow IV drip 26  Dexamethasone eye drops Loftsson T, Hreinsdóttir D, Stefánsson E. Cyclodextrin microparticles for drug delivery to the posterior segment of the eye: aqueous dexamethasone eye drops. J Pharm Pharmacol. 2007 May;59(5):629-35. doi: 10.1211/jpp.59.5.0002. PMID: 17524227. The tear film, especially the very viscous mucin layer immediate to the membrane surface, greatly reduces drug delivery into the eye Passive drug permeation through the membranes is influenced by several factors, such as lipophilicity of the drug molecule, its molecular weight and ionization Dexamethasone is soluble in organic solvent but not in water The most direct approach for introduction of dexamethasone into vitreous is by intravitreal injection Solution/suspension with dexamethasone complexes with cyclodextrin to increase What can you do to increase dexamethasone delivery? solubility Given that stability is not an issue, would you prefer solution, suspension or ointment? and Suspensions showed a higher delivery to the retina most likely due to higher contact why time of the suspension with the cornea Which excipients do you think may be part of this formulation and why One of the cyclodextrins tested works both as solubilizing agent and permeation An agent or polymer to increase the viscosity enhancer Penetration enhancer can also be an option Preservatives, salts (buffer and osmolarity) 27 Sustained release devices Medicated contact lenses or intraocular devices These overcome the potential hazards associated with repeated intravitreal injection such as clouding of the vitreous humor, retinal detachment and endophthalmitis Implantable devices have been developed that serve two major purposes. First, to release of drug at zero order rates, thus improving the predictability of drug action, and second, to release of the drug over several months, reducing dramatically the frequency of administration Vitrasert® is a commercially available sustained release intraocular device for ganciclovir approved for use in-patients suffering from cytomegalovirus 28  Vitrasert® intraocular device a sort of tablet on a support tablet will dissolve/dissociate over time device will need to be surgically removed later on What do you think is the key point of this technology? Controlled release via polymer (erosion or diffusion) - Soluble drugs go through the gelled polymer to be released - Insoluble drugs are released when the polymer erode enough to physically release the particles of the drug trapped in the polymeric matrix 29 Microneedles different types: loaded / dissolvable / plated / reactive (to certain pH or enzyme) Microneedles are custom designed to penetrate only hundreds of microns into sclera, so that damage to deeper ocular tissues may be avoided These needles help to deposit drug or carrier system into sclera or into the narrow space present between sclera and choroid called “suprachoroidal space” (SCS) Puncturing of sclera and depositing drug solution or carrier systems in sclera or SCS may facilitate diffusion of drug into deeper ocular tissues, choroid and neural retina 30 Microneedle scleral patch for delivery to the posterior segment of eye 31 Girdhari Roy, Prashant Garg, Venkata Vamsi Krishna Venuganti, Microneedle scleral patch for minimally invasive delivery of triamcinolone to the posterior segment of eye, International Journal of Pharmaceutics, Volume 612, 2022, 121305, ISSN 0378-5173, https://doi.org/10.1016/j.ijpharm.2021.121305 Dissolvable microneedles made of PVP The different pathways through which the drug can reach the posterior segment of the eye include - cornea – aqueous humor – vitreous humor difference? different characteristic in terms of lipophilicity and hydrophilicity - sclera – choroid – retina – vitreous humor Comparison with intravitreal injection? Depending on the lipophilicity of the substance, the absorption through different part of the eyes may change Advantage compared to injections? Safety and controlled release 32 Progesterone eye drops/insert Progesterone for the treatment of retinite pigmentosa Progesterone has low solubility in water and PBS (7 and 4.4 µg/ml) Low solubility is an issue because it doesn’t allow the delivery of the proper dose Methyl-β-cyclodextrin (βCD) complexation to increase solubility Drops or insert? Drops and insert allow for different kinetics of release and absorption due to different formulation and contact time Adrián M. Alambiaga-Caravaca, Laura G. González Iglesias, Vicent Rodilla, Yogeshvar N. Kalia, Alicia López-Castellano, Biodistribution of progesterone in the eye after topical ocular administration via drops or inserts, International Journal of Pharmaceutics, Volume 630, 2023, 122453, ISSN 0378-5173, https://doi.org/10.1016/j.ijpharm.2022.122453. 33 Release profile of drops, insert over sclera (S-I) and insert over cornea and sclera (C/S-I) Differences can be explained via contact time of progesterone to each structure of the eye and the structure (area) of the insert itself 34 Release profile of insert with different progesterone loading limited Loading is affected by solubility for the eye drops, but it is not a limiting factor for the insert but solubility should still be considered Solubility can affect the drug release from the insert depending on the nature of the polymer and the site of application; while concentration of the drug can affect the push generated by the gradient Drug physical properties (like particle size and solubility) may affect the release from the dosage form both in term of drug loading and the amount of solubilized drug that can generate a concentration gradient pushing progesterone into different tissue where the solubility affects the maximum concentration that can be achieved 35 Effect of tears on tissue distribution Progesterone insert (8h) with saline washing for other 16 hours (24h) No significant difference on the amount of progesterone in every tissue Solubility and permeation through the tissue come into play: saline solution (used to simulate tears) cannot solubilize progesterone well so the removal will be minimal; progesterone trapped into the tissue will more likely do not exit due to its lipophilicity 36 Manufacturing and storage Progesterone is stable for 3 months at 40o degrees with 75% relative humidity 37