Hi, I'd like to help you with your question.
There isn't a medication for jealousy itself. Jealousy comes from a personality issue which stems from either a learned behavior or from a deeper issue such as insecurity. Since these are taught from environmental influences, it is not a mental issue such as schizophrenia or Bipolar disorder. That does not mean that he could not be diagnosed with a mental illness, but it would not be based on jealousy but rather on a personality disorder, which is not treatable by medications. It is treatable by therapy, however.
The other symptom you mentioned your husband having is the racing thoughts and speech. That could indicate a possible disorder, but only if he has other symptoms such as inability to sit still, cannot complete a task, etc. That may indicate a mental health diagnosis that could be treated with medication.
Getting your husband an evaluation by a Master's level therapist would go a long way in figuring out what is causing his behavior. Jealousy is something he learned so getting to the bottom of why he acts out is going to involve him talking this issue out with a therapist. He can contact his doctor for a referral or if he attends church, he can talk with his pastor. Or if he wants to search on line he can try this link: http://therapists.psychologytoday.com/rms/.
Here are some books that can help him get started in helping himself deal with this issue:
If This Is Love Why Do I Feel So Insecure? by Carl G Hindy, J. Conrad Schwarz and Archie Brodsky
How to Deal with Jealousy: Overcoming Jealousy and Possessiveness is Vital for a Healthy Marriage or Relationship. Learn How to Control Your Jealousy Now. by Taylor Timms
Life Without Jealousy: A Practical Guide (10-Step Empowerment Series) by Lynda Bevan
You can find these books on Amazon.com or your local library may have them for you.
I hope this helps you,