Used in conjunction with a Poisoners kit. 
Any and all potions, be they positive or neutral in nature, created and used with malicious intent qualify as a poison and can therefore be made with a Poisoners Kit. 

All advantages, expertise and skills apply. 

Creation of potions can be done discreetly between player and GM/DM but must be announced to the GM/DM that your potion is being used with malicious intent. GM/DM will be the deciding factor in whether your potion and its use, qualifies as malicious.