Pharmaceutical Chemistry

1. UNIT 5
RADIOPHARMACEUTICALS

2. RADIOPHARMACEUTICALS
• These are radioactive substance which are used
therapeutically for treatment and diagnosis.
• These substance get distributed in the body and
emit radiations which used to detect injury,
abnormal cell growth etc.
• Eg: when these x rays passes ,they penetrate
the body tissue ,muscle not bones which gives
x-RAY image ,helps to identify injury or
fractures.. etc

3. Radioactivity
• It is a phenomena in which radioactive
substances or radioisotopes(which are
unstable)undergo decomposition or decay by
emission of radiation/rays to get stable.
• Radiation is emitted from the nuclei of
element.
• There are various types of radiations but most
common types are alpha beta and gamma rays

4. A branch of pharmacy which deals with
radioactive substances or radiopharmaceuticals
are known as radiopharmacy.
• Radiation: Radioactive substances emitted
radiations which is travel through a
medium/space and absorbed by another
medium.

6. ALPHA RAYS
• These are positively charged particles and
heavy in nature.
• They have the least penetrating power.
• These particles are equivalent to the nuclei of
helium atoms.
• They are highly energetic and have energy
upto 4MeV.
• They are less/not useful in pharmacetical
formulation.

7. BETA RAYS/RADIATION
• They are mostly negative charged particles
but rarely may also be positively charged.
• They are much lighter energy particles and
have less ionizing power than alpha particles.
• Beta particles are 8000 times smaller than the
alpha particles.
• Beta particles have negligible masses.

8. GAMMA RAYS
• They are having completely different
charcacter .they do not have any charge or
mass on them.it travels with the same
velocity of light.
• Gamma rays likely X-rays, have shorter wave
lenght than the visible light.
• Penetrating power of gamma rays was found
to be more than alpha and beta rays.

16. DIFFERENCES BETWEEN STABLE
ISOTOPES &RADIOACTIVE ISOTOPES
• ISOTOPES
• Most abundantly found In
nature
• No emission of radiation
• Atomic number and mass
are constant
• Detection by chemical
methods
• Not hazardous(except toxic
chemicals)
• No special handling
precautions.
• No special applications
• RADIOACTIVE ISOTOPES
• Less abundance of natural
radioisotopes
• Spontaneous emission of
radiations(α,β,γ)
• Constantly changing
• Detection by external
detectors like gas
chambers/scintillation
• Special precautions while
handling.
• Special applications in
research/diagnosis(RIA)/
therapy(Rx of cancer)

18. Measurement of Radioactivity
For measuring radioactivity, three
types of devices are available:
1. Gas-filled tube counters e.g. the
Geiger Muller Counter
2. Scintillation Counters
3. Semi-conductor Detectors

19. The Geiger Muller Counter
•The rate of emission of alpha and beta particles
can be detected and measured by this geiger
muller counter.
•Construction: It comprises of a cylindrical
metal tube which act as cathode(negative
charge) and for anode(positive charge) a wire is
placed carefully.
•The metal tube has very low pressure of around
0.1 atm and filled with argon gas.

21. For counting the radioactive solid source, the end
window type G-M counter has been the most
popular.
The window has been made up of an aluminum
alloy (7 mg cm-2), mica or may be a thin glass
bubble (about 15 mg cm-2)
In order to count the medium and high energy
beta particles (above 0.5 MeV) and for gamma
counting thin glass walled counts may be used.
These have been normally of about 1 cm in
diameter . The tube has been coated on the inside
with graphite to form cathode.

22. Scintillation Counters:
A Scintillation Counter works on detecting a flash of
light.which is produced when a charged particle,or X-
rays or gamma rays.
The flashes of light are viewed electronically by
photomultiplier tubes.
The important properties of a good scintillator are :
High scintillation efficiency.
The light produced should be proportional to the
absorbed radiation.
The detector material should be transparent to the
wavelength of its own emission.

23. Semi-Conductor Detectors:
• A semi-conductor is a substance whose electrical
conductivity is between that of a metal and an
insulator. It is noted that Ge(Li)(Germanium with
lithium) Detector.
• semi-conductors ate excellent detectors of γ-rays
with a resolution ten times higher than NaI (Th)
scintillometers.
• The main disadvantage of these is a lower
efficiency for higher energy x-rays. Besides, Ge(Li)
semiconductors need to be cooled by liquid
nitrogen and are hence cumbersome and not
suitable as field instruments.

24. Handling, storage conditions and
Precautions
- The radioactive substances used should comply
with the following characteristics:
• Never work alone in a radioactive lab, especially
not outside normal working hours. Always make
sure to have someone nearby in case of
emergency.
• Take all precautions to prevent radioactive
contamination:
• Radioactive material must be stored in an area not
frequently visited by people. Always separate
radioactive substances from non-radioactive
substances. .

25. • Never bring documents such as notes into the
radioactive zone.
• When handling radioactive materials, always
wear the appropriate protective clothing:
• Wear a lab coat. If there is a risk of serious
contamination, wear disposable clothing. Store
your lab coat away from your regular clothes.
• Always wear gloves when handling radioactive
substances. Regularly check the radiation level of
these gloves. Never touch anything with
potentially contaminated gloves; use paper tissues
.
• Wear shoe covers in rooms where the floor may
be contaminated.

26. • Keep personal items such as handbags, etc.,
outside the lab.
• Wash your hands thoroughly when you leave
the lab.
• To avoid internal contamination, strict hygiene
is essential when handling radioactive
materials
• Eating, smoking, drinking, and applying
cosmetics are prohibited in radioactive labs.
• Never pipette by mouth. Use pipetting devices
.

27. •Regularly check the radiation level of your
working area and all objects used, or at least at
the end of each working day. Replace
contaminated absorption paper.
• Dispose of all radioactive waste in the
appropriate containers.

28. Storage:
•Radiopharmaceuticals should be kept in well-
closed containers in a shielded and suitable
labelled containers .
•stored in an area assigned for the purpose.
•Radiopharmaceutical preparations that are
intended for parenteral use should be kept in a
glass vial, ampoule or syringe that is sufficiently
transparent to permit the visual inspection of the
contents. Glass containers may darken under the
effect of radiation.

29. Labelling of Radioactive Substances
•Every radiopharmaceutical preparation must comply
with the labelling requirements established under Good
Manufacturing Practice.
The label on the primary container should include:
•A statement that the product is radioactive or the
international symbol for radioactivity
•The name of the radiopharmaceutical preparation;
Where appropriate, that the preparation is for
diagnostic or for therapeutic use;

30. • The route of administration;
• The total radioactivity present at a stated date
and, where necessary, time; for solutions, a
statement of the radioactivity in a suitable
volume may be given instead;
• The expiry date and, where necessary, time;
• The batch (lot) number assigned by the
manufacturer;
• The label on the outer package should include:
• A statement that the product is radioactive or the
international symbol for radioactivity
• The name of the radiopharmaceutical
preparation;

31. SODIUM IODIDE I131
• It is radiopharmaceuticals substance used
in the treatment of malignant thyroid. The
ionising radiations of iodine I131 are
absorbed by the thyroid tissue and
damage that tissue.
• The sodium iodide emits about 90% of
beta radiations and remaining 10% is the
alpha radiations.

32. Mechanism
• The iodide enters into thyroid through the
sodium/iodide symporter and accumulate
there. Here it oxidises into iodine and emits
radiations.
• Now these beta radiations destroy thyroid
tissue.

33. Properties
• It is a colorless solution
• It having a PH between 7-10.
• It emits beta and gamma radiations.
• Half life of sodium iodide is 8.4 days.
• Uses
• It is used in the treatment of hyperthyroidism.
• It is also used in radiotherapy of thyroid cancer

34. Pharmaceutical Application of
Radioactive Substances
I. Treatment of Cancers and Tumours
• Americium 241 used as antineoplastic.
• Californium 252 used as antineoplastic."
• Cobalt 60 used as antineoplastic.
• Gold 94 used as antineoplasatic.
• Holmium 66 (26 h) being developed for
diagnosis and treatment of liver tumours.
• Iodine-125 (60 d) used in cancer therapy .

35. II.Treatment of Thyroid Disease with Iodine 131
• Iodine-131 is therapeutically used for to treat thyroid
cancer,
III.Treatment of Arthritis
• Erbium-169: Use for relieving arthritis pain in synovial
joints.
IV.Diagnostic Radiopharmaceuticals
• Ammonia N 13 Injection used for diagnostic coronary
artery disease.
• Chromium 51 used for diagnosis of pernicious anaemia.
• Holmium 166 used for diagnosis and treatment of liver
tumours.
• Iodine 125 used diagnostically to evaluate the filtration
rate of kidneys

36. V. Therapeutic applications:
These radiation have destructive features so
those radiations destroy abnormally multipled
cells and further inhibit the formation of new
cells and tissue. used in the treatment of
disorders like cancers.
VI. Sterilization: Radiations are used to sterilize
the pharmaceutical and surgical instruments in
hospitals.