Isoproterenol Flashcards
What is Isoproterenol?
adrenergic bronchodilator (B1/B2 agonist)
How does Isoproterenol work?
The compound relaxes the smooth muscle in the lungs and opens airways to improve breathing.
What is it used to treat?
- asthma
- chronic bronchitis
- emphysema
- other lung diseases
-relieve cough, wheeze, shortness of breath and troubled breathing by increasing the flow of air through the bronchial tubes.
In Canada, what is Isoproterenol available as?
an injection
In pharmaceutical analysis, a measured signal cannot be interpreted on its own but is often ______
calibrated
What does calibration do?
Calibration enables the analysts to establish the relationship between values of quantities indicated by a measuring instrument, values represented by a material measure or a reference material, and the corresponding values realized by standards.
What is relative calibration?
referred to measurements that are evaluated by comparison with those made on standards or references
What is absolute calibration?
can be evaluated without comparative measurements, but rely instead on fundamental physical and chemical constants and principles
In pharmaceutical analysis, most quantitative measurements use _______ calibration models, while instrumentation calibrations are likely categorized as an ______ calibration
relative
absolute
What is one-point calibration?
It utilizes only one standard as a comparison value. In this instance, it is presumed that this standard is sufficiently reliable and reproducible, and a zero measurement (zero mass, amount or concentration) will produce a zero (or a very well-known value other than zero) response. Between these two values at intermediate mass of the analyze, a linear interpolation is assumed, but no extrapolation beyond the value of the standard is recommended.
What is a multiple-point calibration?
It utilizes more than three different standards (other than zero) to generate the comparison range, which is also considered more accurate and reliable than one-point calibration, because measurement variation is minimized through multiple interpolations. Extrapolation beyond the values of the standards could be reasonably used for calculations as long as linear correlation among standards is satisfactory.
The linear relationship is usually expressed in the following mathematical equation is
y = mx + b
The absorption of electromagnetic radiation of wavelengths between ____ and ____nm by molecules can be employed for both qualitative and quantitative drug analysis.
200 and 800
The relationship between the concentration of an analyte and the intensity of its light absorption is thus the basis of ________
spectrophotometry
Why is spectrophotometry used extensively in drug analysis?
Bc a wide variety of pharmaceutical substances absorb radiation int he near-UV (200-380 nm) and visible (380-800 nm) regions of electromagnetic spectrum
What are some major strengths of UV/visible spectrophotometry ?
1) an easy, inexpensive and robust analytical approach for precise quantitative measurement of drugs in formulations
2) a routine method for physical and chemical characterization of drugs in preformulation and formulation
What are some limitations of UV/visible spectrophotometry ?
1) assay selectivity is somehow low, because it depends on the chromophore (extended systems of double bonds) of individual compounds
ex. a collared drug with an extended chromophore is more distinctive than a drug with a simple benzene ring chromophore
2) analysis of mixtures is difficult because two compounds may have maximum absorbance at the same wavelength
Absorption of radiation by a molecule is mainly governed by two factors. What are they?
- the structure of the chemical molecule
- the wavelength of the radiation
_____ wavelength UV radiation < 150 nm can cause the strongest bonds in organic molecules to break and thus is very damaging to living organisms.
Short
Spectrophotometry uses ______ wavelength UV radiation (>200 nm) for analysis, where weaker bonds in molecules can be excited.
longer
When more double bonds are present in a molecular structure, absorption takes place at _____ wavelengths and with greater intensity.
longer
What law is used to describe the absorption of radiation by the solution of the compound?
Beer-Lambert Law
What is Beer-Lambert Law?
log lo/lt = A = E b c
lo = the intensity of incident radiation lt = the intensity of transmitted radiation
A = absorbance (measure of the amount of light absorbed by the sample)
E = a constant known as the molar extinction coefficient (the absorb of a 1 M solution of the analyte)
b = the path length of the cell in cm (usually in 1 cm)
c = the concentration of the analyte (mol/litre)
In pharmaceutical products, what are drug concentrations and amounts expressed in?
grams or milligrams instead of moles
How is the Beer-Lamber Law written to reflect this?
A = A(1%, 1cm) b c
Where:
A = the measured absorbance
A(1%, 1 cm) = the absorbance of a 1% (1g/100mL, w/v) solution in a 1 cm cell
b = the path length of the cell in cm (1 cm)
c = the concentration of the analyte (g/100 mL)
With the known values of A(1%, 1 cm) for drug substances, drug concentration of a particular preparation can therefore be calculated from what equation ?
c = A / A(1%, 1 cm)
List the 3 basic components in a UV/visible spectrophotometer
- light sources
- monochromator
- optics
Describe:
Light Sources
A deuterium lamp for the UV (190-350nm) light wavelength and a quartz halogen or tungsten lamp for the visible (350 - 900 nm) light wavelength
Describe:
Monochromator
It disperses the light into its constituent wavelengths that are further selected by the slit. A monochromator can also rotate so that a range of wavelengths is passed through the sample as the instrument scans across the spectrum of the test compound
Describe:
Optics
It is designed to split the light beam so that the light passes through two sample compartments. In such an instrument, a blank solution (standard) is used to correct the reading or spectrum of the sample; this blank is usually the solvent tin which the sample is dissolved
List 3 examples of UV/visible spectrophotometry use in pharmaceutical analysis
- partition coefficient
- solubility
- drug release
Describe:
Partition Coefficient
The partition coefficient of a drug between water and an organic solvent may be determined by shaking the organic solvent and the water layer together, and determining the amount of drug in either the aqueous or organic layer by UV spectrophotometry
Describe:
Solubility
The aqueous solubility of a drug may be simply determined by shaking the excess of the drug in water until equilibrium is reached and then using UV spectrophotometry to measure the concentration of the rug that has gone into solution
Describe:
Drug Release
Samples of drug dissolution testing are collected at different time intervals, and the concentration of the drug in each sample is measured using UV spectrophotometry. This approach is applicable only to simple tablet preparations in which excipients do not interfere with the active ingredient at its maximum detection wavelength. Otherwise, sample pretreatment (extraction) or chromatographic separation will be needed before UV detection
List other types of spectrophotometry
1) Infared (IR) Spectrophotometry
2) Atomic Spectrophotometry
Describe Infared (IR) Spectrophotometry
the use of electromagnetic radiation ranging between 2500 and 20000 nm for structural confirmation
Describe atomic spectrophotometry
the use of thermal excitation to atoms so that they emit light and radiation emitted is measured, which is normally used in control of ions such as sodium, potassium, and lithium in raw materials and formulations
Lab procedure:
Describe your visual observation of Isoproterenol HCl injection
clear, no foreign substances
Describe the preparation of:
Standard stock solution
- Pipette 10 mL of pre-prepared standard solution, containing 1 mg/mL of isoproterenol hydrochloride to a 200 mL volumetric last, dilute with water to volume, mix completely
- This is your STANDARD STOCK SOLUTION
Describe the preparation of:
Final calibration solutions
-Pipette 14, 16, 18, 20, and 22 mL of this solution into 5 separate 25 mL volumetric flasks and
ADD
-0.5 mL of freshly-prepared ferrous sulphate citrate solution
-2.0 mL of amino acetate buffer to each flask
-Allow to stand for 20 mins (CRITICAL STEP) then dilute to 25 mL with water. Mix well.
-These five solutions are your final calibration solutions
Describe the preparation of:
Stock test solution
- Carefully open the isoproterenol injection vial, transfer the 2 mL injection solution to a small test tube using the syringe/needle.
- Accurately pipette 1.0 mL of the injection into a 100 mL volumetric flask, dilute with distilled water to the volume.
- Mix well
-This is your stock test solution
Describe preparation of:
Final test solution
- Accurately pipette 20 mL of the above dilute solution into a 25 mL volumetric flask.
- Add 0.5 mL of freshly prepared ferrous sulphate citrate solution
- Add 2 mL of amino acetate buffer
- Allow this to stand for 20 minutes (Critical step) and then dilute to 25 mL with water.
- Mix well
-This is your final test solution
Describe the sample measurement using the spectrophotometer
- Measure both your calibration solutions and your test solution with a spectrophotometer at 540 nm (visible wavelength) at the same time
- When transferring the calibration samples, start from the lowest concentration first (can use the same plastic disposable pipette for all calibration samples)
- Use a new clean plastic disposable pipette for the test sample
- Use distilled water for the blank cell
- Record absorbance readings for all testing samples
go over calculations
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