500 Dalton rule
G_500DAWhat does this word mean?
A widely cited guideline stating that molecules below 500 Da can be absorbed through skin, based on Bos and Meinardi in Experimental Dermatology in 2000.
Expanded note
The rule rests on three observations about small molecules: almost all common contact allergens are below 500 Da, most topical dermatological drugs are below 500 Da, and all known transdermal drug-delivery drugs are below 500 Da. The site uses it as the conceptual anchor for the molecular-scale visualisation. IMPORTANT BOUNDARY: the rule was not designed with large nucleic-acid molecules in mind, so it cannot serve as the direct verdict on whether PDRN penetrates. Measured data show PDRN does reach the superficial viable epidermis at an extremely low rate.
Not a generic example.
PDRN at 50-1500 kDa is 100 to 3000 times the threshold, yet human in vivo measurement still records 3.06% relative permeation at 24 h.
Related terms
Where this term appears
Educational reference only. This site does not provide medical advice, treatment courses, injection counts, clinic recommendations or price recommendations.
PDRN is not approved by the FDA for injection or any therapeutic use. Topical and injectable PDRN are parallel facts under different regulatory pathways and must not be directly equated.
PN is not PDRN. Evidence grades are labelled on every factual element; in vitro and animal research is never described as clinical efficacy.