Crosslinked hydrogel-based transdermal pharmaceutical formulations. The hydrogel transdermal formulations. Transdermal patches are useful for administering a variety of drugs to patients. The transdermal patches here employ crosslinked-hydrogels generated through irradiation, thus eliminating any residual effects associated with chemical- or UV-based crosslinking procedures. The transdermal patches may be formed from a variety of high-molecular weight polymeric compounds and include substantial levels of water to improve skin tolerance by the patient. The transdermal patches may also include transcutol as a solvent for the drug, which has been found to increase the effectiveness of drug delivery. The present disclosure also provides for methods of loading a drug into a transdermal formulation after the crosslinking of the hydrogel, thus improving stability and bioavailability through avoiding exposure of the drug to the radiation used in the crosslinking procedure. The transdermal patches here are particularly effective in delivering lidocaine to patients in need thereof.