I don't understand why they drugged Kate/Sawyer/Jack. In the last scene of of the finale, the others had them under total control and even covered their heads. Wondering if that might be how they gathered information? Got them to talk about stuff under the influence of the drug?

They obviously took some blood sample from them, and I imagine that is a lot easier if the person is sedated than struggeling....

Yeah i would imagine the needle marks are from blood being drawn more then drugs. While they said they were drugged id imagine they could've used those dart's they had used to take them out in the field when they were otw with michael.

They obviously took some blood sample from them, and I imagine that is a lot easier if the person is sedated than struggeling....

Yeah , that makes sense, except for the fact that they took blood from Michael without drugging him. I'm just trying to figure out the significance of the prevalence of drugs on the island.