EditorialReports made during the last decades, mention the development of drug resistance mechanisms acquired by tumor cells and bacteria. To-date, the multiple drug resistance (MDR) identified for the malignant tumor cells [1][2][3] and bacteria (Mycobacterium tuberculosis, Staphylococcus aureus, Escherichia coli etc.) [4] is well documented. With respect to this challenge the science community is asked to find solutions in order to fight MDR and the research efforts may be included in two main categories: (a) development of new medicines and (b) identifying new ways to make efficient again the existing ones.The promotion of new medicines is costly, needs sustained efforts and takes long time. Approaching new methods to make the existing medicines efficient in fighting MDR is more convenient, cheaper, faster and simpler, the more so because the medicines utilized to treat particular maladies may become, once modified, efficient in the treatment of completely different illnesses than targeted by the parent compounds.A promising procedure applied to produce modifications of medicines at molecular level consists in exposing them in solutions at laser radiation that has particular characteristics in terms of wavelength, energy/power, time distribution of the emission (i.e. continuous wavecw or pulsed), pulse duration and repetition rates; according to the present knowledge, the polarization state of the beams and their time and spatial coherence do not have critical influence on the processes Comparative data were obtained on the evolution of neovascularisation of the conjunctive between untreated rabbit eyes and eyes impregnated with cytostatics at 5x10 -5 M in natural saline which are exposed to coherent or noncoherent light beams. The model simulates the tumor and the tests have shown that conjunctive and neovascularisations disappear after 1-2 treatments. 5-FU is a pyrimidine analog that belongs to the family of antimetabolites. It is weakly fluorescent, but it emits intense fluorescence after exposure to UV-VIS light. The UV-VIS absorption spectra of 5-FU did not show any structural modification after exposure to UV laser beams, but the FTIR spectra showed that the molecular geometry of 5-FU was changed after irradiation. The exposure to UV laser radiation transformed the 5-FU molecule into a tautomeric form. The increase of the fluorescence is attributed to a higher conversion to the keto-enol (lactim form) fluorescing tautomer due to monochromatic and high intensity laser radiation, which allows an effective and selective excitation. The radicals formed by the deprotonation of 5-FU could initiate the tumoricidal effect. The spectroscopic studies were coupled with preliminary tests on 5-FU photosensitizing properties measured on rabbit eyes conjunctive tissues [2]. Comparative data were obtained about the evolution of neovascularisations in the conjunctive tissue between untreated rabbit eyes and eyes impregnated with 5-FU 10 -4 M in natural saline and exposed to a UV-light beam emitted by a nitrogen pulsed l...