Orally inhaled pharmaceutical products are widely used to treat asthma and chronic obstructive pulmonary disease, as well as more recently being used to deliver larger molecules such as proteins and peptides for a wider variety of therapies. In the example of a pressurized Metered-Dose Inhaler (pMDI) used for asthma treatment, a self-propelled fine-particle aerosol containing the drug is released from the inhaler. The proportion of the drug dose that does not reach the lungs causes a reduction in therapeutic effectiveness and may lead to side effects such as oral thrush. This article presents a CFD model of full respiratory tract drug deposition from a pressurised Metered Dose Inhaler (pMDI) using HFA-134a propellant. Using this model, the impact of varying injection angle on therapeutic efficiency is investigated. Anatomical human airway geometry based on CT scan data was used in the simulation, from the mouth and throat down to generation eight in the lower right lobe. A hexahedral mesh was applied with prism layers. Steady, multiphase, multispecies, two-way coupled simulations with Lagrangian particle tracking were constructed using the k-omega SST turbulence model in Simcenter STAR CCM+. The simulations modelled the pMDI at near peak actuation with a 60m/s HFA vapour inlet and 30LPM co-flow of air. Liquid droplets were injected at 60m/s with 0.9:0.1 mass fraction HFA and Ethanol respectively. Lobe specific ventilation ratios of each of the five lung lobes was also implemented. The continuous flow characteristics seen in the anatomical geometry corroborated with previous research, both experimental and simulated. In depth post-processing of results was carried out, allowing regional drug deposition to be analysed. Steady simulations overpredicted total drug mass deposition, however, regional deposition was representative; larger particles were deposited directly on the tongue and finer particles reached the lungs. It is common when using a pMDI that the patient can lack control of the device angle during delivery into the mouth, which can result in the spray either pointing toward the roof of the mouth, or directly onto the tongue. The simulation methodology developed was able to be efficiently re-purposed to evaluate the therapeutic effectiveness of a pMDI device administered at different injection angles. The computationally efficient steady approach enabled fast exploration of the design space in-silico. Regional deposition analysis showed a small window of optimal efficacy where lung delivery was maximised. Post processing also allowed visualisation of propellant evaporation as the liquid droplets travelled through the airway, a key phenomena which is almost impossible to observe in-vitro. These simulation tools can be used early on in the design process to improve inhaled device efficacy, accounting for human anatomy, operating conditions and usage variability, as well as steering opportunities for future robust device development.