Medicare coverage depends on doctor's DIAGNOSIS which must be "cachexia related to cancer" along with dose not exceeding FDA label maximum for the diagnosis. I do not know the FDA rules. The "alternative" is just dronabinol, the generic name of marinol. Marinol is synthetic THC, an oil/liquid at room temp, but provided as gel tabs which must be kept refrigerated. Marinol is NOT the CBD discussed on TV for kids. THC in the brain works on the cannaboid system, making it a unique drug with many untouched applications. Marinol takes 2.5-3 hours to be absorbed and have an effect. The effects last only about 3 hours. See below for details on this limitation.
I am a PhD scientist and engineer with cancer, autoimmune and have bipolar. The following is from personal experience plus scientific investigation. Feel free to share.
Consider a good pain med like hydrocodone (or other opioid) for pain in Stage 4. Nausea can wait until chemo as there are many covered drugs prescribed at the time of chemo. Plus, not everyone gets nauseous (I did not). For wasting, any well-liked food (ice cream, steak, potatoes, cake!) will work better than the marinol; marinol dehydrates the body and induces a drive to eat salty foods like chips which then induce a drive to drink fluids; marinol will not, therfore, lead to any effective eating; fatten up first.
Warnings: Those with normal or low BP, problems with oxygenation, co-administration of meds that may slow respiration or increase dehydration, or meds that treat psychiatric disorders should try marinol first at a single low dose and self-observe changes - physically and mentally - to ensure continued oxygenation, BP and manageable mood. For me, low-dose marinol maintains a nice, stable mood on top of my bipolar meds; it also eliminated the need for sleep meds.
I take marinol for migraines which, it turns out, were due to very high blood pressure 200/120. (No other type of med even touched my BP or pain. I am in perfect physical shape too!) I pay $800/month for 4 2.5 mg (lowest-dose) marinol per day to stay out of pain. Medicare and Humana will not cover marinol for pain or BP since manufacturers have not submitted these applications to the FDA. In addition, dosage and timing are big problems...
Doctors do not understand that (1) the only available form - refrigerated gel tabs - do not take effect until 2.5 hours and (2) the effects only last for another 3 hours. To maintain my highly beneficial 140/90 BP and eliminate brain-exploding migraines, I take one 2.5 mg every 6 hours. This does not make me high. Doctors will instead prescribe you a higher dose (say 5 mg instead of 2.5) and fewer pills, resulting in sudden impact (possibly hallucigens) with an effect that lasts just as short a time. MARINOL NEEDS AN EXTENDED-RELEASE FORMULATION along with better education of doctors.
It is probably cheaper to buy pot. As a PhD scientist, I prefer the regulated synthetic THC which I can control rather than off-the-street pot. Pot contains CBD which also affects the brain and all the crap in the smoke. Many medical users of pot will take one or two puffs every so often as needed; it's their way of regulating the effects. Beyond cost, most complaints about marinol are related to the prescribing doctor's giving a smaller number of pills with a high dose. The high dose will give a "high," often psychedilic, which medical users do not want; and the good effects do not last long. For marinol, one 5 mg twice a day is medically not the same as one 2.5 mg four times a day.
The care center should be expert on filing for maximum Medicare coverage. But Part B covers only 80% of allowed charges. It has been our experience that Medicare rates have been excepted. Still the 20% not covered is the patient's responsibility and is much more than $100 in our experience. We also have private Medigap insurance which helps with that cost.
The care center should provide help on ways to meet the costs, including Medicaid if you qualify. They may have other resources you can utilize.