Compared to the other triblock copolymers used in this study, A-pPentOx-A has been been much less explored for formulation development. Recently, an ultra-high drug loaded A-pPentOx-A/BT-44 formulations (BT-44 solubility ≈ 9 g/L at 10 g/L polymer feed) was reported. At all the tested ratios, the solubility of BT-44 was decreased by 90% by day 30. This poor stability was further investigated in detail to confirm, if the drug BT-44 is crystallizing like previously reported A-pBuOx-A/MT formulation or this decreased in solubility is because of the formulation agglomeration. The DSC measurements confirmed the presence of amorphous BT-44. Additionally, the dynamic light scattering experiments (at 173°, at room temperature) revealed the relatively bigger hydrodynamic diameter (Dh) of 115 nm for plain polymer at 10 g/L concentration. The results obtained by DLS were further corroborated by cryo-TEM analysis where the plain polymer at 10 g/L and BT-44 formulation at 10/2 g/L polymer/BT-44 feed, appeared as worm like structures. In general, based on these recent findings, the poor stability of A-pPentOx-A formulation for the majority of drugs tested here, can be correlated to the polymer aggregation/agglomeration behaviour. Recently, depending upon the drug feed, Lim et al. observed the transition of freshly prepared A-pBuOx-A/Olaparib spherical micelles (Dh ≈ 10-30 nm) to worm like structures (Dh ≈ 200 nm) in the time span of 72 hours . While, the small angle neutron scattering (SANS) revealed the core shell morphologies in the case of plain A-pBuOx-A polymer .