Some consider habitual lip licking or picking to be a form of nervous tic, and do not consider this to be true angular cheilitis, instead calling it perlèche (derived from the French word pourlècher meaning "to lick ones lips"), or "factitious cheilitis" is applied to this habit. The term "cheilocandidiasis" describes exfoliative (flaking) lesions of the lips and the skin around the lips, and is caused by a superficial candidal infection due to chronic lip licking. Less severe cases occur during cold, dry weather, and is a form of chapped lips. Individuals may lick their lips in an attempt to provide a temporary moment of relief, only serving to worsen the condition.The sunscreen in some types of lip balm degrades over time into an irritant. Using expired lipbalm can initiate mild angular cheilitis, and when the person applies more lipbalm to alleviate the cracking, it only aggravates it. Because of the delayed onset of contact dermatitis and the recovery period lasting days to weeks, people typically do not make the connection between the causative agent and the symptoms. Nutritional deficiencies
Several different nutritional deficiency states of vitamins or minerals have been linked to AC. It is thought that in about 25% of people with AC, iron deficiency or deficiency of B vitamins are involved. Nutritional deficiencies may be a more common cause of AC in Third World countries. Chronic iron deficiency may also cause koilonychia (spoon shaped deformity of the fingernails) and glossitis (inflammation of the tongue).
As it is so heavily bound to plasma proteins haemodialysis is unlikely to be helpful in cases of overdose.Early symptoms of overdose can include:

It is worth noting, however, that may of these symptoms are also indicative of kidney failure and hence may be masked by the patients condition.Late symptoms of overdose include:

Mechanism of action
Like 1,25-dihydroxyergocalciferol, paricalcitol acts as an agonist at the vitamin D receptor and thereby lowers parathyroid hormone levels in the blood. Pharmacokinetics
The plasma concentration of paricalcitol decreases rapidly and log-linearly within two hours after initial intravenous administration. Therefore, it is not expected to accumulate with multiple dosing, since paricalcitol is usually given no more frequently than every other day (3 times per week). == References ==