What is the principle of the CMIA (chemiluminescent microparticle immunoassay) method on the Architect i1000?
- technology used to determine the presence of antigens, antibodies, and analytes in samples
- uses paramagnetic microparticles coated with a capture molecule specific for the analyte being measured
- also uses an acridinium-labeled conjugate, pre-trigger, and trigger solutions
What is the reaction sequence for the architect?
- pipettor dispenses microparticles into sample in reaction vessel; vortexer mixes reaction mixture
- reaction mixture incubates and analyte present in sample binds to the corresponding capture molecules on the microparticles forming the immune complex
- magnet attracts paramagnetic microparticles to a wall of the reaction vessel; wash zone manifold washes the reaction mixture to remove unbound materials
- pipettor dispenses a chemiluminescent acridinium-labeled conjugate; conjugate binds to the immune complex to complete the reaction mixture
- reaction mixture incubates
- wash zone manifold washes the reaction mixture to remove unbound materials
- pre-trigger nozzles dispenses pre-trigger solution and the CMIA optical system takes a background read
- trigger nozzle dispenses trigger solutions to the reaction mixture; acridinium undergoes an oxidative reaction when exposed to peroxide and an alkaline solution; reaction causes the chemiluminescent reaction to occur; N-methylacridone forms and releases energy as it returns to its ground state
- CMIA optical system measures the chemiluminescent emission over a predefined time period to quantitate the analyte concentration or to determine qualitative interpretations for index assays
What is the purpose of the Pre-Trigger solution?
- contains 1.32 % (w/v) hydrogen peroxide
- creates an acidic environment to prevent early release of energy (light emission), the pre-trigger solution helps to keep the microparticles from clumping and it splits acridinium dye off the conjugate bound to the microparticle complex. this action prepared the acridinium dye for the next step
What is the purpose of the Trigger solution?
- containing 0.35% N sodium hydroxide
- when added to the reaction mixture will cause the acridinium to oxidate. this reaction causes the chemiluminescent reaction to occur
- N-methylacridone forms and releases energy (light emission) as it returns to ground state
What is accomplished during daily maintenance?
- clean the outside of the probes in the wash zone
- mix the microparticle bottles on the reagent carousel
- dry the vacuum pump filter
How often are controls run on the Architect for immune suppressant drugs?
once every 24 hours when ISD drugs are analyzed, after calibration or major maintenance, or for troubleshooting
Which method principle is used to measure Immunosuppressant drugs on Architect i1000?
The Architect Cyclosporine assay is a chemiluminescent microparticle immunoassay (CMIA) for the quantitative determination of cyclosporine in human whole blood on the Architect i System
What is the specific requirement for Immunosuppressant drugs?
whole blood EDTA
What is meant by the term Immunosuppressant?
also known as anti-rejection drugs, are used to prevent the body from rejecting a transplanted organ
What are the clinical applications of Immunosuppressant drugs?
- used to control severe manifestations of allergic, autoimmune, and transplant-related diseases
- some drugs have a diffuse effect on the immune system while others have specific targets; drugs with diffuse effects are more likely to cause damaging adverse effects, but the effectiveness of the more specific drugs may be reduced if their action can be bypassed by alternative metabolic pathways
- treatment protocols frequently use drug combinations to minimize adverse effects and to prevent resistance to treatment
- protocols are essential to allow scientific evaluation, the clinician must be prepared to tailor treatment based on the ongoing assessment of drug effects, disease activity and the robustness of the individual patient
What organ and/or system are suppressed when sirolimus, tacrolimus, or cyclosporine are administered?
- sirolimus –> kidneys (renal transplant)
- tacrolimus –> liver, kidneys, T-cell proliferation
- cyclosporine –> heart, liver, kidneys
Define Pharmacokinetics
mathematical interpretation of drug disposition over time to determine proper dosing amounts of a therapeutic drug
Define First-order kinetics
the rate of change of concentration of a drug is dependent on the drug concentration
Define Zero-order kinetics
the rate of change of concentration of a drug is independent of the concentration of the drug and dependent on the metabolism of the drug
What are the 5 steps that occur in changes in drug concentration over time once the drug is taken?
- liberation: release of the active ingredient of the dose
- absorption: process by which the drug molecule is taken up into systemic circulation
- distribution: typically occurs between 30 minutes and 2 hours, the process of drug molecules leaving the bloodstream and entering the extravascular space or into tissues
- metabolism: the process of transformation of the parent drugs into its metabolites
- elimination: process of excretion of the drug from the body
What is the purpose of monitoring immune suppressant drugs?
to ensure drugs are in the therapeutic range and not causing drug toxicity and to monitor transplant patients
What are some toxic side effects that can occur when taking the ISDs?
nephrotoxicity and hepatotoxicity
What are the reference ranges for sirolimus, tacrolimus, and cyclosporine?
- sirolimus: 5.0-17.0 ng/mL
- tacrolimus: 5.0-20.0 ng/mL
- cyclosporine:
i. 1st month: 225-280 ng/mL
ii. 2nd month: 170-225 ng/mL
iii. 3rd month: 115-170 ng/mL
iv. >3 months: 85-115 ng/mL
What are the factors that could increase a patient’s chance for drug toxicity?
- decreased renal clearance caused by kidney disease
- administration of another, possibly interactive, drug at the same time
- altered serum protein binding caused by liver disease
- inappropriate timing of a blood draw to check therapeutic levels leading to overdosing
What role does folate play in the body? What are the physiological outcomes of of folate deficiency?
- essential for DNA synthesis for the development of new cells
- macrocytic/normochromic anemia
Prior to running an RBC folate, what needs to be done to prepare the specimen? What type of specimen is used for RBC folate testing?
- hemolysis of RBCs, incubated away from light for 90 mins
- specimen is to be collected in an EDTA tube
