Radiopharmaceuticals are radioactive compounds used for diagnosis and treatment of diseases. They have two components - a radionuclide and a pharmaceutical. The pharmaceutical is chosen based on its localization in a specific organ, then a radionuclide is attached. Radionuclides undergo radioactive decay, emitting particles or radiation. Ideal radiopharmaceuticals have a short half-life, emit gamma rays, localize only to target tissues, and are easily prepared. They are used for both disease treatment by delivering radiation to sites, and diagnosis by imaging organ accumulation of emitted gamma rays.

1. BY
VANA JAGAN MOHAN RAO M.S.Pharm, MED.CHEM
NIPER-KOLKATA
Asst.Professor, MIPER-KURNOOL
Email: jaganvana6@gmail.com

2. What is Radiopharmaceuticals?
A radiopharmaceutical is a
radioactive compound used for the
diagnosis and therapeutic treatment
of human diseases.
A radiopharmaceutical has two
components:
a radionuclide and
a pharmaceutical.

3. Introduction
In designing a radiopharmaceutical, a
pharmaceutical is first chosen on the basis of
its preferential localization in a given organ or
its participation in the physiologic function of
the organ.
Then a suitable radionuclide is tagged onto
the chosen pharmaceutical such that after
administration of the radiopharmaceutical,
radiations emitted from it are detected by a
radiation detector.

4. Introduction
Isotopes of an atom have the same number of protons, but a
different number of neutrons.
Radioisotopes & Radionuclides: Unstable isotopes which are
distinguishable by radioactive transformation.

5. Radioactivity: the process in which an unstable
isotope undergoes changes until a stable state is
reached . When the atomic nucleus undergoes
spontaneous transformation, called radioactive
decay, radiation is emitted (alpha particles, beta
particles and gamma rays).

6. Introduction
• Radiation refers to particles or waves coming
from the nucleus of the atom (radioisotope or
radionuclide) through which the atom
attempts to attain a more stable configuration.

7. Important parameters
Radioactive decay is the process in which an
unstable atomic nucleus spontaneously loses
energy by emitting ionizing particles and
radiation.
Physical half-life is the period of time required
to reduce the radioactivity level of a substance to
exactly one half its original value due solely to
radioactive decay.
Biological half-life the time required for a living
organism to eliminate one-half of a radioactive
substance which has been introduced into it.

8. Effective half life
The time required for a radioactive element in
an animal body to be diminished by 50% as a
result of radioactive decay and biologic
elimination.
Te = ( Tp X Tb) ( Tp + Tb )
isotope T(ph) T(b) T(e)
3H 4500 12 12
99mTc 0.25 1 0.2
235U 26000000000
0
15 15
226Ra 580000 16000 15000

9. Ideal radiopharmaceutical properties
 Short half-life isotope(Ideally 1.5 times the duration
of the diagnostic procedure.)
 Energy of Gamma Rays: (Ideal: 100-250 keV)
 Pure gamma emitter
 Target to Non target Ratio
 Localization only in tissue desired
 Easy preparation
 Economy price

10. RADIOACTIVE DECAY TYPES
When an unstable nucleus decays, It may give out:
1. Alpha particle decay
2. Beta particle decay
3. Gamma ray

11. Penetrating power
Alpha particles may be
completely stopped by a
sheet of paper, beta particles
by aluminum shielding.
Gamma rays can only be
reduced by much more
substantial mass, such as a
very thick layer of lead.

12. Alpha particledecay
Alpha particles are made of 2 protons and 2
neutrons.
This means that when a nucleus emits an
alpha particle, its atomic number decreases by
2 and its atomic mass decreases by 4.
Alphaparticles are relatively slow and
heavy and have a low penetrating power .
Because they have a large charge, alpha
particles ionize other atoms strongly.

13. Beta particle decay
Beta particles have a charge of minus 1. This
means that beta particles are the same as an
electron.
This means the atomic mass is unchanged
the atomic number increases or decreases by 1.
They are fast, and light.
Beta particles have amedium penetrating power.
Beta particles ionize atoms that they pass, but not
as strongly as alpha particles do.

14. Gamma ray
Gamma rays are waves, not particles.
This means that they have no mass and no
charge.
Gamma rays have a high penetrating power.
Gamma rays do not directly ionize other atoms,
although they may cause atoms to emit other
particles which will then cause ionization.

15. Radioactive materials
1 Natural radioactivity:
Nuclear reactions occur spontaneously
2 Artificial radioactivity:
The property of radioactivity produced by
particle bombardment or electromagnetic
irradiation. All radionuclides commonly
administered to patients in nuclear medicine
are artificially produced.

16. Types of artificial radioactivation:
A- Charged-particle reactions(cyclotron)
B- Photon-induced reactions(nuclear
reactor)
C- Neutron-induced reactions(radionuclide
generator)

17. Neutron-induced reactions
It is the bombardment of a non-
radioactive target nucleus with a source
of thermal neutrons in a device called a
Radionuclide Generator.

18. Radionuclide Generator
 Radionuclide generators contain a parent
radionuclide that decays to produce a
radioactive daughter. The parent is usually
produced in specialized nuclear reactor

20. Example:
technetium-99m, obtained from a
generator constructed of molybdenum-99
absorbed to an alumina column.
Parent: 99Mo as molybdate
Half-life: 66 hr.
daughter:
half-life:6hr

21. Application of radiopharmaceuticals
1 Treatment of disease:
They are radiolabeled molecules designed to deliver
therapeutic doses of ionizing radiation to specific
diseased sites.
2 As an aid in the diagnosis of disease:
The radiopharmaceutical accumulated in an organ of
interest emit gamma radiation which are used for
imaging of the organs with the help of an external
imaging device