Our 45 yer old son has unpredictable mood swings, irrational behavior, angry, lies, etc. At other times is outgoing, friendly, normal.?

Many causes. On the surface this could be bipolar disorder, but it can be seen in drug and alcohol abuse, brain diseases such as post head trauma, seizures and ms. Confront on drug use, encourage evaluation for others when in the friendly state.
Substance abuse? Substance abuse and addiction can present in such a way. It is something to consider. Hopefully he is open to being evaluated for both physical and emotional issues that are causing his labile behavior.
See a doctor. It sounds like your son may have a psychiatric disorder. There are a few considerations (for ex bipolar disorder) but the diagnosis should come out an actual evaluation by his primary care doctor or psychiatrist.