Race
Although pseudoporphyria has no predilection toward any one race, it has been shown that fair-skinned children who are highly prone to sunburn are more likely to develop naproxen-induced pseudoporphyria than those children with skin types III or higher. Wallace et al. demonstrated that even in the absence of a history of blistering, children with light skin and blue or green eyes are at an increased risk of developing shallow scars on the face while taking naproxen. Causes
Pseudoporphyria can be induced by a wide range of medications, excessive UV-A exposure, and hemodialysis. One frequently reported drug is naproxen. A frequent source of UV-A exposure is tanning booths. As recognition of pseudoporphyria increases and the number of new medications expands, the list of etiologic agents associated with pseudoporphyria will most likely continue to grow. Agents associated with pseudoporphyria are as follows:
Propionic acid derivatives (NSAIDs) - naproxen, diflunisal, ketoprofen, oxaprozin, mefenamic acid, rofecoxib
Ketone NSAID-nabumetone
Antibiotics - nalidixic acid, tetracycline, oxytetracycline, ampicillin-sulbactam, cefepime, fluoroquinolones (M Poh, personal communication, June 1999)
Antifungals - voriconazole
Diuretics - furosemide, chlorthalidone, butamide, triamterene/hydrochlorothiazide
Antiarrhythmics - amiodarone
Chemotherapy - 5-fluorouracil
Immunosuppressants - cyclosporine
Sulfones - dapsone
Vitamins - brewers yeast, pyridoxine
Vitamin A derivatives - etretinate, isotretinoin
Muscle relaxants - carisoprodol/aspirin
Nonsteroidal antiandrogens - flutamide
Other - hemodialysis, excessive UV-A, cola, oral contraceptive pills (levonorgestrel and ethinylestradiol), narrowband UV-B phototherapy (rarely)

Pathophysiology
The precise pathophysiologic mechanism of pseudoporphyria is not fully understood. Some drugs, especially non steroidal anti-inflammatory drugs, can trigger pseudoporphyria in the presence of ultraviolet light. The pathophysiology of pseudoporphyria associated with hemodialysis has not been fully explained. Aluminum hydroxide has been implicated in hemodialysis-associated pseudoporphyria.
MNP belongs to the nitrosamine class of compounds, some of which are classified as probable or possible human carcinogens (substances that could cause cancer), based on laboratory tests such as rodent carcinogenicity studies. Although there are no data available to directly evaluate the carcinogenic potential of MNP, information available on closely related nitrosamine compounds was used to calculate lifetime exposure limits for MNP.As of January 2021, the FDA continues to investigate the presence of 1-methyl-4-nitrosopiperazine (MNP) in rifampin or 1-cyclopentyl-4-nitrosopiperazine (CPNP) in rifapentine approved for sale in the US. Names
Rifampicin is the INN and BAN, while rifampin is the USAN. Rifampicin may be abbreviated R, RMP, RA, RF, or RIF (US). Rifampicin is also known as rifaldazine, rofact, and rifampin in the United States, also as rifamycin SV.Its chemical name is 5,6,9,17,19,21-hexahydroxy-23-methoxy-2,4,12,16,18,20,22-heptamethyl-8-[N-(4-methyl-1-piperazinyl)formimidoyl]-2,7-(epoxypentadeca[1,11,13]trienimino)-naphtho[2,1-b]furan-1,11(2H)-dione 21-acetate. Rifampicin is available under many brand names worldwide. References
External links
"Rifampicin". Drug Information Portal. U.S. National Library of Medicine.