They work by removing excess porphyrins from the liver via increasing the excretion rate by forming a coordination complex with the iron center of the porphyrin as well as an intramolecular hydrogen bond between a propionate side chain of the porphyrin and the protonated quinuclidine nitrogen atom of either alkaloid. Due to the presence of the chlorine atom, the entire complex is more water-soluble allowing the kidneys to preferentially remove it from the blood stream and expel it through urination. Chloroquine treatment can induce porphyria attacks within the first couple of months of treatment due to the mass mobilization of porphyrins from the liver into the blood stream. Complete remission can be seen within 6–12 months as each dose of antimalarial can only remove a finite amount of porphyrins and there are generally decades of accumulation to be cleared. Originally, higher doses were used to treat the condition but are no longer recommended because of liver toxicity. Finally, due to the strong association between PCT and Hepatitis C, the treatment of Hepatitis C (if present) is vital to the effective treatment of PCT. Chloroquine, hydroxychloroquine, and venesection are typically employed in the management strategy. Epidemiology
PCT prevalence is estimated at 1 in 10,000. An estimated 80% of porphyria cutanea tarda cases are sporadic. The exact frequency is not clear because many people with the condition never experience symptoms and those that do are often misdiagnosed with anything ranging from idiopathic photodermatitis and seasonal allergies to hives.
Society and culture
Porphyria cutanea tarda is implicated in the origin of vampire myths. This is because people with the disease tend to avoid the sun due to photosensitivity and may develop disfigurement that eats away their noses, eyelids, lips, and gums giving their teeth a fang-like appearance. It has also been suggested they may have developed a craving for healthy blood to replace their own in a self medicated treatment in prior centuries. Some folklore scholars claim that this is a mistake, first suggested in the 1990s, because vampires of myth did not have photosensitivity, nor were they described as looking like the modern incarnation of vampires. They were described as unintelligent roaming beings who fed on their victims to the point that they became reddened and heavily bloated, fattened on blood. Fangs were very rarely mentioned. Photosensitivity was not added to the vampire mythology until the 1922 film Nosferatu. Count Dracula of Bram Strokers novel could walk about freely in daylight unharmed but not as powerful in the book.Porphyria cutanea tarda is the name of a song by the rock band AFI on their fourth album Black Sails in the Sunset, released on May 18, 1999.Porphyria cutanea tarda is the disease that both Dabney Pratt and Brother Rush suffer from in Virginia Hamiltons childrens novel Sweet Whispers, Brother Rush. References
External links
Porphyria cutanea tarda at NIHs Office of Rare Diseases