No - unless the non-Part D drug is used for a medically-accepted indication.

Specific prescription medications are excluded from the Medicare Part D program or sometimes medications are removed from the market due to FDA health or safety concerns - and your Medicare Part D plan will not provide a temporary supply or 30-day transition fill for a drug excluded from Medicare Part D or a medication that was removed from the marketplace.

As noted by the Centers for Medicare and Medicaid Services (CMS) under "Part D Supplementary (Excluded) Drugs":

"[t]he definition of a covered Part D drug excludes any drug for which as prescribed and dispensed or administered to an individual, payments would be available under Parts A or B of Medicare for that individual, even though a deductible may apply.  In addition, the definition of a covered Part D drug specifically excludes drugs or classes of drugs, or their medical uses, which may be excluded from coverage or otherwise restricted under Medicaid under section 1927(d)(2) of the [Social Security] Act, with the exception of smoking cessation agents. The drugs or classes of drugs that may currently be otherwise restricted under Medicaid include:

• Agents when used for anorexia, weight loss, or weight gain (even if used for a non-cosmetic purpose (i.e., morbid obesity)).
• Agents when used to promote fertility.
• Agents when used for cosmetic purposes or hair growth.
• Agents when used for the symptomatic relief of cough and colds.
• Prescription vitamins and mineral products, except prenatal vitamins and fluoride preparations.
• Nonprescription drugs.
• Covered outpatient drugs which the manufacturer seeks to require as a condition of sale that associated tests or monitoring services be purchased exclusively from the manufacturer or its designee.
• Agents when used for the treatment of sexual or erectile dysfunction (ED)." [emphasis added]

(see also: https://www.cms.gov/Medicare/ Prescription-Drug-Coverage/ PrescriptionDrugCovContra/ downloads/ PartDDrugsPartDExcludedDrugs.pdf)

Drugs excluded from Part D by the FDA

Likewise, if the U.S. Food and Drug Administration (FDA) finds that a medication is harmful, the drug may be dropped from the Medicare Part D program, and you will not be allowed a transition fill - in such a case, you would need to work with your physician or prescriber to find an alternative medication that is covered by Medicare and your Medicare Part D plan. Please note, if the FDA announces that a drug is no longer approved and a Medicare Part D plan sponsor removes a non-Part D drug from [the plan's] formulary; CMS expects that Part D sponsors will provide 30 days of advance notice of the formulary removal.

Example Coverage of Non-Part D Erectile Dysfunction (ED) Drugs

Some non-Part D drugs can be approved for Medicare Part D coverage when they are used to treat an approved condition or medically-accepted indication (as defined in section 1927(k)(6) of the Social Security Act).

For example, the erectile dysfunction drug Cialis (r) has received FDA approval to treat BPH (benign prostatic hyperplasia (enlarged prostate).  In such a case, this non-Part D drug may be covered by your Medicare Part D plan for the treatment of an approved condition - and be subject to a transition fill.

As noted by CMS,

"[erectile dysfunction or] ED drugs will meet the definition of a Part D drug when prescribed for medically-accepted indications approved by the FDA other than sexual or erectile dysfunction such as pulmonary hypertension.

However, ED drugs will not meet the definition of a Part D drug when used off-label, even when the off label use is listed in one of the compendia found in section 1927(g)(1)(B)(i)of the [Social Security] Act: American Hospital Formulary Service Drug Information, and DRUGDEX® Information System.  ED drugs meet the definition of a Part D drug only when used for FDA-approved indications."

More about Bonus Drugs or Supplemental Benefit Drugs

Some Medicare Part D prescription drug plans cover non-Part D "Bonus Drugs" such as cosmetic drugs, erectile dysfunction drugs, or other "lifestyle drugs".  If a Bonus Drug is covered by a Medicare Part D plan, the coverage will have no effect on your actual Medicare Part D plan limits (for example, meeting the initial deductible, entering the Donut Hole, or meeting your out-of-pocket limits (TrOOP)).  And your Medicare drug plan is not required to offer a transition fill for your non-Part D Bonus Drugs.

As noted by CMS:

"While these [non-Part D] drugs or uses are excluded from basic Part D coverage, Part D sponsors can generally include them as part of supplemental benefits [or Bonus Drugs], provided they otherwise meet the definition of a Part D drug.  Because over-the-counter (OTC) drugs do not otherwise meet the definition of a Part D drug, they may not be included as part of supplemental benefits; however, under certain conditions as part of a plan utilization management program, OTC drugs can be provided at no cost to enrollees. The cost of these drugs to the Part D sponsor would be treated as administrative costs under such programs."

(sources include: CMS Medicare Prescription Drug Benefit Manual, Chapter 6 – Part D Drugs and Formulary Requirements, Section 30.4 - Transition (Rev. 18, Issued: 01-15-16, Effective: 01-15-16; Implementation: 01-15-16))