PHARMACOLOGY OF INJECTION, ORAL AND TRANSDERMAL FORMS

This scientific article provides an in-depth analysis of the pharmacological properties of injection (intravenously, intramuscularly), oral (by mouth) and transdermal (through the skin) forms of drug delivery at the PhD level. The advantages, disadvantages and clinical use of these forms are compared, with special attention to pharmacokinetic parameters (bioavailability, T_max, C_max, t_1/2, volume of distribution, clearance) and pharmacodynamic aspects (receptor interaction, ED_50, development of tolerance). Although injection forms provide almost 100% bioavailability and rapid action, they are limited by their invasiveness and risk of infection; Oral forms are convenient and inexpensive, with bioavailability reduced to 10-50% due to first-pass metabolism; transdermal systems provide 70-95% bioavailability by continuous release (zero-order kinetics) and bypassing the first-pass effect, but skin permeability creates limitations. Examples include fentanyl (oral 33-50%, transdermal 90-92%, IV 100%), insulin (oral almost 0%, injectable 100%) and other drugs. The possibilities of optimization through new technologies (microneedle, iontophoresis, nanocarriers) and compartmental models are discussed. The article highlights the role of these forms in personalized medicine and provides directions for future research.