Method of treating skin diseases

A method for treating skin diseases in an animal which comprises topically treating an animal in need of such treatment with an effective amount of a hydro-monobenzoporphyrin (Gp) having a light absorption maximum between 670-780 nm;

• wherein the Gp is selected from the group consisting of ##STR17## and mixtures thereof and the metalated and labeled forms thereof, wherein each R.sup.1 and R.sup.2 independently selected from the group consisting of carbalkoxy (2-6C), alkyl (1-6C) sulfonyl, aryl (6-10C) sulfonyl, aryl (6-10C);
• cyano;
• and --CONR.sup.5 CO-- wherein R.sup.5 is aryl (6-10C) or alkyl (1-6C);
• each R.sup.3 is independently carboxyalkyl (2-6C) or a salt, amide, ester or acylhydrazone thereof, or is alkyl (1-6C);
• and
• R.sup.4 is CHCH.sub.2, CH.sub.2 OR.sup.4', --CHO, --COOR.sup.4', CH(OR.sup.4')CH.sub.3, CH(OR.sup.4')CH.sub.2 OR.sup.4', --CH(SR.sup.4')CH.sub.3, --CH(NR.sup.4'.sub.2)CH.sub.3, --CH(CN)CH.sub.3, --CH(COOR.sup.4')CH.sub.3, --CH(halo)CH.sub.3, or --CH(halo)CH.sub.2 (halo), wherein R.sup.4' is H or alkyl (1-6C) optionally substituted with a hydrophilic substituent;
• or
• wherein R.sup.4 is an organic group of <12C resulting from direct or indirect derivatization of vinyl;
• or
• wherein R.sup.4 consists of 1-3 tetrapyrrole-type nuclei of the formula --L--P wherein --L-- is selected from the group consisting of ##STR18## and P is selected from the group consisting of Gp which is of the formula 1-6 but lacking R.sup.4 and conjugated through the position shown as occupied by R.sup.4 to L, and a porphyrin of the formula:
• ##STR19## wherein each R is independently H or lower alkyl (1-4C);
• wherein two of the bonds shown as unoccupied on adjacent rings are joined to R.sup.3 and one of the remaining bonds shown as unoccupied is joined to R.sup.4 and the other to L;
• with the proviso that if R.sup.4 is CHCH.sub.2, both R.sup.3 cannot be carbalkoxyethyl;
• and irradiating the animal with light absorbed by said Gp.