Targetted drug therapy using Light

1. PHOTOPHARMACOLOGY
“As A targeted drug delivery ”
By
Dr. M. Archana
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2. INTRODUCTION
Photopharmacology is an emerging approach in
medicine.
Principle:
Involves activating and deactivating photo
switchable molecules with light for target drug
delivery.
PhotoPharmacology is opening new avenues in
regulation of biological systems in a precie manner
using using drugs.
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3. From A.majus –
methyoxypsoralen isolated
Activated by sunlight
potent photosensitizer
efficacious at low doses in
management of Vitiligo
Heliotherapy- controlled
sun exposure
Then developed
artificial source of light
PUVA therapy n
psoriasis
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4. AIM
Reduce Systemic
And
Environmental
Drug Toxicity
Reduce chances of
drug resistance
Achieving
selectivity /
precision in
treatment
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5. MODES of ACTION 5

6. PHOTODYNAMIC
THERAPY
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7. Porfimer sodium (Photofrin) : FDA
approved in Palliation for Ca
oesophagus (1995)
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8. PHOTO-UNCAGING
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9. PHOTO
SWITCHING
Widely Used Tool
Molecule reversibly changes
its chemical and/or optical
properties upon light
irradiation.
By introducing Photoswitches
into the drug like ,
Azobenzene, spiropyran,
diarylethene
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10. Example
Photo Switching
COMBRESTATIN-
An Anti Cancer Drug
Binds to microtubues & polymeric
proteins
inhibit the cancer cell cytoskeleton
Azobenzene analogue of Combrestatin
– shining violet light 390-430nm
changes it to cis isomeric form – more
cytotoxic
Shining with Green Light – Less Active
Trans Form
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11. PRESENT
STATUS
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12. Optogenetics is a biological technology for
controlling cellular activity with light.
Combination of methods from optics and
genetics
Aims in switching -
On (Gain-of-function) Or Off (Loss-of-function)
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13. CHALLENGES
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Delivery of photons to target tissues
Lower energy photons are prone to scattering in tissue and absorption
by endogenous chromophores
Photo damage of cells can occur
These limit the depth of penetration and are responsible for the toxicity
of UV light

14. Conclusion
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Light offers an unparalleled opportunities as a non-invasive regulatory element for
biological applications .
It shows a great degree of orthogonality towards most elements of chemical and
biochemical systems.
Photons do not cause contamination
Light can be delivered with very high spatial and Temporal precision
Light - regulated in a qualitative and quantitative manner by adjusting wavelength
and intensity respectively.
It is envisioned that in years to follow, numerous new applications for
Photopharmaceuticals will emerge.

15. Sonopharmacology
Photopharmacology
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