Which chemicals or drugs available only to doctors cause significant loss of current memories, specifically memories within the past few years and recently rather than your childhood memories?
First, let's define retrograde amnesia carefully. You'll find many sources listing drugs that cause retrograde amnesia but they're using the term incorrectly.
Retrograde amnesia is a form of amnesia where someone is unable to recall events that occurred before the development of the amnesia, even though they may be able to encode and memorize new things that occur after the onset.
With that definition in mind, I don't think drugs exist that cause retrograde amnesia for the past few days, much less years. Some drugs will create retrograde amnesia for memories formed minutes before administration, but not much longer than that. This is believed to be because they interfere with the memory formation process, which is still incomplete when the drug is taken.
Long term alcohol abuse can cause retrograde amnesia, but that's due to the brain damage it causes after long-term abuse. No single binge, even a long one, will cause retrograde amnesia if the abuse is short-lived.
There are animal experiments that have produced retrograde amnesia by administering agents directly to the brain, but that's not something a doctor can give you. They may lead to such drugs in the future, but they're not available yet.
There are several drugs that can prevent new memories from being formed such as alcohol, benzodiazepines, and anesthesia agents such as propofol, but they all work by preventing new memories from being formed while under influence of the drug. They don't wipe out memories formed before the drug was taken and therefore can't be said to cause retrograde amnesia.
So, basically, true retrograde amnesia is usually due to brain damage from agents such as dementia, trauma, stroke, infection, prolonged seizures, and long-term substance abuse. There are no drugs a doctor can give you that will accomplish this.