Parenterals 1 Flashcards
What does parenteral refer to? What are the main routes?
- refers to administration by injection
- the main routes are SC, IM, and IV
What are the advantages of using parenterals?
- rapid onset of action, complete and predictable bioavailability and avoidance of the GI tract
- reliable route for comatose, very ill and uncooperative patients. Allows a high dose of medication
What are the disadvantaged of parenterals?
- frequent dosing, pain, cost, and medication errors difficult or impossible to reverse
In what cases are parenterals useful?
- parenteral route useful for drugs showing unreliable GI absorption, inactivation or destruction by the GI tract, extensive first pass or mucosal metabolism
- heparin, insulin, EPO and some antibiotics
- useful route when patient requires rapid, assured high blood levels or constant blood levels
- lidocaine for arrhythmias
Syringes, needles and administration sets
syringe is needed for measuring injectable products
- may be glass or plastic
- consists of a barrel and plunger
- glass preferred if it is to be stored in syringe for a protracted period of time
- graduations on barrel allow for measurement
- sizes - 1-60 mL
Why are syringes always disposable?
- cost
- cross contamination with AIDS or hepatitis
Describe the needs on the syringe?
- used for penetrating the skin
- are hollow, made from stainless steel
- have a hib at one end for attaching a syringe and usually have a sharp beveled tip at the other end
- lengths vary from 3/8 - 6 inches and outside diameter ranges form 10-27 gauge with larger gauge value referring to smaller diameter
What does the selection of needle gauge and length depend on?
What do the variations of needles include?
- site of administration
- nature of the product being injected
- variations include butterfly needles for pediatrics and teflon or silastic cannulas for long term use
What does an IV administration set consist of?
- basic set consists of spike, drip chamber, tubing, roller clamp, end fitting compatible with hub of a needle or cannula
- vented needed for rigid glass bottles; non-vented for flexible plastic bags
- many variations such as Buretrol
Describe the subcutaneous route of administration
- for vaccines, insulin
- volume smaller than 2 mL and short, fine needle used
- usual body site arms, legs and abdomen
- rotate sites
- hypodermoclysis is variation where 250-1000 mL may be given when veins are not available
Describe the intramuscular route of administration
- injected into striated muscle fibres
- usual sites are deltoid, lateral or gluteal muscles
- usual volume 1-3 mL; if > 5 mL use multiple sites
- take care not to enter a vein
- needle usually 19-21 G and 1 inch
- risk of nerve damage
- allows controlled release or sustained release with oil vehicles
Describe the intravenous rote of administration
- direct into lumen of vein
- extremely rapid predictable response
- avoids tissue irritation and GI tract
- difficult or impossible to revers if error occurs
- care to avoid extravasation and too rapid a rate
- drugs with short 1/2 life give loading dose and then a maintenance dose
- volumes usually 1-100 mL and rate 1mL/10-20 sec although for some drugs rate specific to avoid toxicity or irritation
- drugs need to be in solution for this route although emulsions can also be used
- large proximal veins are generally used for rapid dilution of drugs
What happens to drug volumes larger than 100 mL?
- they are LVP and are used for fluid and electrolyte replacement
What are the options for adding drugs that are used for intermittent infusion?
- piggybacking them into the IV or giving them by push through a device like Buretrol
Describe the intrathecal route of administration
- drug administered directly into the CSF
- product must be of high purity, preservative free and free of particles
- since route bypasses the BBB, some drugs like the antineoplastic vincristine must never be given this way
- this is DIFFERENT from epidural where the drug is injected outside the dural membrane and within the boney spinal caudal canals
- inta-ocular product must be of similar quality to intrathecal (ITH)
When microbial populations are exposed to heat, radiation or antimicrobial death of cells follow what process?
- first order process
What is the ‘D value’?
- the time interval known as the decimal reduction time
- its the time interval required to bring about 1 decimal reduction of the microbial population (1000 to 100, for example) - works out to being a 90% reduction
What is sterility?
the absence of viable microorganisms - can only be determined by sterility testing of the entire batch (sterility assurance level is more practical)
What sterility assurance level is acceptable?
SAL is 6 is acceptable
What is the Z factor?
- the temperature increase needed to provide a decimal reduction time
(generally as temperature is higher, need shorter exposure times)
What would a non-linear plot of log survivors be caused by?
- cell clumping
- mutations more resistant to process
- populations of mixed species
What are some common sources of microbial contamination?
- atmosphere (microorganisms associated with particulates- often generated by people)
- water (esp pseudomonas sp)
- raw materials (controlled by USP microbial limits testing)
- packaging (mold spores from paper)
- people
What are the 5 methods of sterilization that the USP recognizes?
- steam
- dry heat
- filtration
- gas
- ionizing radiation
In what way is kaolin sterilized?
potentially high bioburden
In what way is petrolatum sterilized?
- steam penetration
Drug subject to hydrolysis has stability issues related to ___
heat
What is a disinfectant?
- substance used on inanimate objects to render them non-infectious
What is an antiseptic?
- substance used on animate objects to kill microorganisms to prevent them from multiplying
What is bacteriostatic?
-a substance that prevent multiplication of microorganisms-often used as preservatives
What is terminal sterilization?
a process where sterilization is the final procedure
What is steam sterilization?
- widely used procedure that is efficient, quick and inexpensive
- product container must be permeable to steam
- product and content not damaged or altered by heat
- pyrogens are NOT affected by steam
Describe how an autoclave works?
- operations at 121 degrees and 15 psi
- steam enters from the top and displaces air from the bottom through traps and valves (gravity displacement)
- large systems may use a vacuum pump to remove air
- air steam mixtures not as efficient as DRY steam