drgopal
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India,
2007-05-29 13:11
(6615 d 20:11 ago)

Posting: # 752
Views: 7,641
 

 precautions for lightsensitive drugs [Bioanalytics]

hi,
What are the special precautions and regulations to be followed while doing a BA/BE study for a lightsensitive drug?

drgopal


Edit: Category changed. [Helmut]
Helmut
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Vienna, Austria,
2007-05-29 14:47
(6615 d 18:36 ago)

@ drgopal
Posting: # 754
Views: 6,101
 

 lightsensitive drugs (suggestions)

Hi drgopal!

Let’s consider 2 phases were degradation may occur: clinics and analytics.

Clinics
Generally lightsensitive drugs are well protected during sampling, because:
  1. Glas vials (vacutainers) are almost perfect shields for UV-radiation.
  2. The entry-depth of light into whole blood is in the range of a few millimeters only.
  3. If your compound has a similar absorption wavelength as compared to albumin, such a compound may be well protected after centrifugation in plasma / plastic tubes.
In my experience working in the clinical stage under light protection (e.g., sodium vapour lamps) leads to a lot of difficulties in venipuncture, sampling errors, etc.
Plasma vials (3) may be wrapped in aluminium foil or dip-coated.

If you are over-cautious, you may try to validate 1 & 2, but:
be prepared to difficulities anyway, because you would have to spike whole blood in vacutainers. IMHO, you end up with very variable results; therefore more than the usual 6 replicates must be considered.

Analytics
  1. Analytes in stock solutions and sample extracts are much more susceptible to light-degradation than plasma samples.
  2. You should validate all sample preparation steps under varying light conditions (day light through [closed!] windows, fluorescent light, dimmed light, sodium vapour light), and different light protection measures (glass vials, brown glass vials, PP vials, etc).
  3. Dont’t forget to close the lid of the autosampler. ;-)
As in clinics, the dimmer the light the more sample preparation errors are likely to occur.
You should find an optimum between sufficient light protection and practicability.

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drgopal
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India,
2007-05-30 12:00
(6614 d 21:22 ago)

@ Helmut
Posting: # 758
Views: 5,979
 

 lightsensitive drugs (suggestions)

Hallo sir,
Thanks for your reply. If the drug is for psoariasis what are the restrictions for the subject in the study (protection from light) and how will we take care of packing and transportation of the biological samples?
Regards
drgopal


Edit: Full quote removed. Please see this post! [Helmut]
Helmut
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Vienna, Austria,
2007-05-30 15:22
(6614 d 18:01 ago)

@ drgopal
Posting: # 761
Views: 6,227
 

 lightsensitive drugs (suggestions)

Dear drgopal!

❝ If the drug is for psoariasis what are the restrictions for the subject in the study (protection from light) […]



Are you talking about Methoxsalen?

To quote Martindale (2002):
Adverse Effects:
Effects on the eyes.
Free methoxsalen has been detected in the lens of the eye for at least 12 hours after oral administration1 although it may become integrated into the structure of the lens and cataracts may occur in patients who fail to wear suitable eye protection for 12 to 24 hours after therapy. However, provided that eye protection is used there appears to be no significant dose-dependent increase in the risk of cataract formation […]. Psoralens may also increase the sensitivity of the retina to visible light.
Precautions:
Methoxsalen should not be given to patients with diseases associated with light sensitivity such as porphyria, although it is used with care to decrease some patients' sensitivity to sunlight.
Patients should not sunbathe for 24 hours before and 48 hours after PUVA treatment. They should avoid exposure to sun, even through glass or cloud cover for at least 8 hours after methoxsalen ingestion and patients should wear wrap-around UVA absorbing glasses for 24 hours after ingestion.
Interactions:
Food.
Some foods, for example, celery, parsnip, and parsley, contain psoralens and consumption of large quantities may increase the risk of phototoxicity with methoxsalen.

❝ […] and how will we take care of packing and transportation of the biological samples?


I don’t think that you have to follow special precautions, because samples in a box will be protected form light anyhow… ;-)

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