Limitations: This safety classification applies only to preparations containing a combination of the two drugs prilocaine and felypressin. The same ATC-code (N01BB54) can in some countries be used for different combinations of prilocaine and other drugs which in theory may be porphyrinogenic. Please refer to the classification and monograph of each individual substance. If the combination contains a substance which is not classified (NC) or has been classified as porphyrinogenic (PSP, PRP or P), the safety classification of such a combination as PNP is no longer valid. Prilocaine: Used uneventfully in 105 patients with latent or active acute porphyria. By clinical criteria the local anaesthetic prilocaine is not porphyrinogenic. Felypressin: Not metabolised by CYP. Pharmacodynamic or side-effect porphyrogenicity not probable. Felypressin is probably not porphyrinogenic.

Prilocaine hydrochloride is a local anaesthetic of the amide type. Felypressin is a synthetic nonapeptide. It is freely soluble in water.

Prilocain is a local anaesthetic. Felypressin is a synthetic vasopressin analogue used as vasoconstrictor. It is added to prolong the effect of prilocaine and to reduce the hepatic exposure and the risk of systemic reactions.

Prilocaine hydrochloride is metabolized principally in the liver. Some metabolism of prilocaine may also occur in the kidneys. Prilocaine is excreted in urine as various metabolites and less than 1% as unchanged drug. Not been found to be an inducer or irreversible inhibitor of drug metabolizing cytochrome P450 species (Rendic, 2002). Felypressin is not metabolised by CYP.

Thunell, S., study to be published: 105 patients exposed without porphyric adverse reaction reported. Andersson: Reports to have frequently used it in infiltrations without ill effects.

Uneventful use reported in 1 patient with acute porphyria. Also prilocaine (N01BB04) has been used uneventfully by 6 patients with acute porphyria.