Sterile compounding
From Rx-wiki
In a healthcare setting, sterile compounding can be viewed simply as the preparation of products in a manner that prevents and/or removes contaminents from the final product prior to administration or use of the product. Some sterile products commonly prepared by pharmacies may include intermittent piggybacks of antibiotics, injectable hazardous drugs, parenteral nutrition, ophthalmic preparations, etc.
In this article we will provide a brief overview of the terminology, regulations, and best practices associated with proper preparation of sterile prodducts.
Contents
Common routes
To get started, we should define the term parenteral. In order to define this, we should look at its root words:
- para/o = despite, other than, or beside
- enteron = meaning the alimentary canal, more commonly referred to as the GI tract
- -al = a suffix meaning pertaining to
So, based on that we can define parenteral as a route of administration other than the GI tract. Technically this includes everything from topical medications and inhalation therapies to ear drops and injections, but today the term parenteral is intended to mean various kinds of injections and infusions and generally excludes all other routes of administration.
The following is a short list of parenteral routes of administration and is by no means considered comprehensive, but is instead intended to provide some examples of these various routes.
- Intravenous - (IV) into a vein
- Intramuscular - (IM) into a muscle
- Subcutaneous - (SC, SQ) under the skin
- Intraarterial - (IA) into an artery
- Intracardiac - (IC) into the heart
- Intrathecal - (IT) into the spinal canal
- Intradermal - (ID) into the skin itself
- Intraperitoneal - infusion or injection into the peritoneum
- Epidural - infusion or injection into the epidural space (the outermost part of the spinal canal)
- Intravitreal - through the eye
- Intraosseus infusion - through the bone marrow
- Intrahepatic - into the liver
- Intracerebral - into the cerebrum
- Intracerebroventricular - into the cerebral ventricles
- Intravesical infusion - into the urinary bladder
- Intracavernosal injection - into the base of the penis
Many lists will also include inhalation and ophthalmic as they also need to be sterile.
Charcteristics
Additional precautions need to be kept in mind when preparing parenterals because they are able to avoid many of a patient's barriers to absorption due to how they are administered. These special considerations are that:
- solutions for injection must be sterile – i.e., free from bacteria and other microorganisms,
- solutions must be free of all visible particulate material,
- all parenteral solutions must be pyrogen-free,
- the solution must be stable for its intended use,
- the pH of an intravenous solution should not vary significantly from physiological pH (approximately 7.4), and
- intravenous solutions should be formulated to have an osmotic pressure similar to that of blood (isotonic).
Visual inspection
Parenteral solutions should always be held up before a bright light and be visually inspected for precipitation or crystallization prior to the parenteral leaving the pharmacy.
Terminology
To better understand the concepts addressed in this article, we should briefly establish definitions for some common terminology.
- aseptic techniques
- techniques or methods that maintain the sterile condition of products
- pyrogens
- chemicals produced by microorganisms that can cause pyretic (fever) reactions in patients
- osmotic pressure
- a characteristic of a solution determined by the number of dissolved particles in it
- isotonic
- when a solution has an osmolarity equivalent to that of blood
- hypertonic
- when a solution has a greater osmolarity than that of blood
- hypotonic
- when a solution has a lesser osmolarity than that of blood
- ions
- molecular particles that carry electric charges
- additive
- a drug that is added to a parenteral solution
- admixture
- the resulting solution when a drug is added to a parenteral solution
- lyophylized
- freeze-dried
- diluent
- a solvent that dissolves a lyophylized powder or dilutes a solution
- friction fitting, luer lock, eccentric, oral
- different types of syringe tips
- hub
- the part of the needle that attaches to the syringe
- shaft
- the stem of the needle that provides the overall length of the needle
- bevel
- an angled surface at the tip of the needle
- gauge
- a measurement; with needles, the higher the gauge, the smaller the lumen (and the thinner the needle)
- lumen
- the hollow center of a needle
- coring
- when a needle damages the rubber closure of a parenteral container causing fragments of the closure to fall into the container and contaminate its contents
- depth filter
- a filter located in the hub of the syringe that can filter solutions being drawn into or expelled from a syringe, but not both ways in the same procedure. This kind of filter uses a tortuous pathway.
- membrane filter
- a filter that filters solution as the solution is expelled from the syringe through a membrane.
- final filter
- a filter that filters solution immediately before it enters a patient's vein.
- HEPA filter
- a high efficiency particulate air filter
- laminar flow
- continuous air movement at a uniform rate in one direction
- total parenteral nutrition (TPN) solution
- complex solutions with two base solutions (amino acids and dextrose) and additional micronutrients
- osmosis
- the action in which drug in a higher concentration solution passes through a permeable membrane to a lower concentration solution
- dialysis
- movement of particles in a solution through permeable membranes
- USP <797>
- USP Chapter <797>, Pharmaceutical Compounding: Sterile Preparations, is the first set of enforceable sterile compounding standards issued by the United States Pharmacopeia (USP). USP Chapter 797 describes the procedures and requirements for compounding sterile preparations and sets the standards that apply to all settings in which sterile preparations are compounded.
- CSP
- compounded sterile preparation, this is a product whose sterility is maintained during preparation.
- ACD
- automated compounding device, a machine used to prepare CSPs (e.g., TPN).
- hazardous drugs
- these are drugs that are known to cause genotoxicity, carcinogenicity, teratogenicity, and/or the potential to cause fertility impairment. These drugs can be classified as antineoplastics, cytotoxic agents, biologic agents, antiviral agents and immunosuppressive agents. This is why safe handling of hazardous drugs is crucial.
- antineoplastic drug
- drugs that inhibit and combat the development of tumors.
- irrigation
- large volume solutions used during surgical, urological, or renal procedures to bathe and moisten tissues.
- precipitate
- an insoluble substance separated from a solution due to a reaction between incompatible substances.
- nosocomial infection
- an infection acquired while in the hospital.
