The drug release rates of poorly soluble medications such as doxorubicin has been investigated in this paper. Since the drug was fixed, different carriers used to deliver it and their release rates compiled from literature were evaluated in this paper. Even though targeting of drugs is very important in drug delivery, it is not within the scope of this paper. However, functionalization of the carrier may provide this benefit, those constructs are included for comparison in terms of hybrid constructs. Dendrimer, micelles and hybrid constructs used in the delivery of doxorubicin compared in this paper with respect to carrier size and drug loading. Assuming that the dissolution follows a slow release, 40-50% of the drug in the phase I representing a sudden or the burst release, followed by a steady release of 50-60% of the drug in phase II, not all the carriers and their sizes exhibited this behavior. Carriers and hybrid constructs 38nm size were more effective where phases I and II observed, however, as the size decreased to 34 nm or increased above 40nm, minimal release occurred meaning the carriers were too big to penetrate the vasculature permeability. Nano-carriers, dendrimers, micelle, hybrid dendrimers and micelles were found to be effective with the carrier manufacturing, generation, polymer, molecular weight of the carrier and other parameters. The release rate of doxorubicin was found to be effective with dendrimers together with hybrid dendrimer exhibiting a bilinear behavior. Micelles 20nm were more effective representing 60% of release in 10 hours followed by additional 25% in 35 hours exhibiting a bilinear behavior. Size greater than 20nm resulted in slow release reaching less than 10 to 40% of drug. Several drugs exhibited multiple slopes in their kinetics when micelle was used. The therapeutic efficacy of hybrid micelle was superior to other nano-carriers.