MO14 Quality Control 1 Drug Quality and IR Spectroscopy Flashcards
What is the difference between a medical dossier and a pharmacopoeia?
Medicine dossier is included in a new medicine application for a new medicine (either new active ingredient, way of administration etc.) to demonstrate efficacy, safety and quality when trying to get a new drug approved by medsafe. The pharmacopoeia is for when the patent for a medicine runs out and other companies want to make their own version of the drug, they have to prove it works the same way and have a set of standards to compare their new version to.
What are the 3 main objectives in the monograph of the pharmacopeia?
- Verification of identity, is the active ingredient present?
- Homogeneity, are the impurities below a certain threshold?
- Purity, how much of the drug is the active ingredient?
What tests can be done to verify the identity of a drug?
NMR (nuclear magnetic resonance, expensive but very effective), infrared spectroscopy, mass spectrometry
What are you testing for when testing the homogeneity of a drug?
Residual solvent and heavy metals from manufacturing process, inorganic materials
How does infrared spectroscopy identify drugs?
IRS identifies the presence or absence of functional groups which are separated by wavenumber represented by peaks. It does this as when the molecule is hit with IR radiation, it causes the molecule to absorb some of that energy and the chemical bonds start to vibrate or stretch.
What characteristics of a bond determines its wavenumber in IR Spectroscopy?
- The mass of the 2 atoms
- Bond order (how saturated the bond is, double or triple bonds will stretch less).
When the
What is conjugation?
When a molecule has alternating single and double bonds causing electron delocalisation where the p-orbitals are overlapping. This allows electrons in the bond to move freely across the molecule. This lowers the overall energy and increases stability of the molecule.
What law/equation do the bonds in a molecule obey when hit with infrared radiation?
Hookes Law where:
V is the frequency of vibration
K is the force constant or bond ‘stiffness’
M1 and M2 is the reduced mass of the 2 atoms
What vibrates faster?
1. Heavy atoms or light atoms
2. Unsaturated or saturated bonds
- Light atoms (decrease M1M2, inversely proportional to v)
- Unsaturated bonds
What is the fingerprint region of an IR spectrum?
- less than 1500
- Unique for every compounds so spectra may by compared for a match eg. From pharmacopoeia
- contains unique bends and rocking
- hard to interpret
What is the effect of conjugation on stretching bands?
- decreased pi-character
- increased sigma character
-double bond is longer and weaker than expected
-decreased K in the hookes law equation therefore decreased frequency and wavenumber
