Resiniferatoxin for the Management of Refractory Morton s Neuroma Pain

* INCLUSION CRITERIA: Both male and female participants are eligible for study evaluation. There are no exclusions for any racial/ethnic groups. Efforts will be made to extend accrual to a representative population. In order to be eligible to participate in this study, an individual must meet all of the following criteria: * Provision of signed and dated informed consent form. * Ability of subject to understand and the willingness to sign a written informed consent document. * Must be able to read, write, understand, and complete English-language study-related forms and adequately communicate in English. * Stated willingness to comply with all study procedures and availability for the duration of the study. * Male or female, aged 18 and older. * In good general health as evidenced by medical history. * Diagnosed with one painful Morton s neuroma in the index foot * Has not attained satisfactory pain relief with conservative, oral analgesic and at least one kind of injection treatment for Morton s neuroma. * Exhibits moderate to severe foot pain due to the Morton s neuroma (average worst pain \>= 5 on the 0-10 numeric pain rating scale NRS) as assessed verbally at \>= 3 individual days during prescreening. * For females of reproductive potential who are sexually active: use of highly effective contraception for at least 1 month prior to screening and agreement to use such a method during study participation and for an additional one (1) month after administration of RTX. If a female, be sterile (surgically or biologically) \* or at least one year postmenopausal\*\*, or have a monogamous partner who is surgically sterile, or have a same sex partner, or if in a heterosexual relationship, must agree to do the following for at least one month after receiving investigational product (IP): * Practice abstinence, or * Use at least one of the following medically acceptable methods of birth control: * Hormonal methods such as oral, implantable, injectable, vaginal ring, or transdermal contraceptives (must have started a minimum of 1 full cycle, based on the subject s usual menstrual cycle period, before IP dose * Intrauterine device * Double-barrier method (condoms, sponge, or diaphragm with spermicidal jellies or cream). * Defined as having had a hysterectomy and/or bilateral oophorectomy, bilateral salpingectomy or bilateral tubal ligation/occlusion at least 6 weeks prior to screening; or having a congenital or acquired condition that prevents childbearing * Defined as at least 12 months with no menses without an alternative medical cause) \[can be confirmed with follicle stimulating hormone level (FSH) in the post-menopausal range (FSH levels \>=40 milli international units/mL (mIU/mL) at Screening) if the subject is not on hormonal replacement therapy\] * For males of reproductive potential who are sexually active: use of condoms or other methods to ensure effective contraception with partner for one (1) month after administration of (RTX). If a male of reproductive potential, unless he has a same sex partner or a partner who is sterile or at least one year post-menopausal, must agree to do the following for at least one month after receiving IP * practice abstinence from heterosexual activity or * use (or have their partner use) acceptable contraception (see criterion above) during heterosexual activity Male study participants should not donate sperm for 3 months after RTX injection. EXCLUSION CRITERIA: An individual who meets any of the following criteria will be excluded from participation in this study: * Pregnancy or lactation. * Has a known allergy or hypersensitivity to chili peppers or capsaicin. * Has a known allergy to local anesthetics. * Has active or history of rheumatoid arthritis or peripheral neuropathy. * Has a prolonged baseline QTc interval exceeding 480 milliseconds. * Current presentation of other currently painful pathology of the same foot affected by Morton s neuroma, including, but not limited to, hallux valgus, plantar fasciitis, hammer toes, metatarsalgia, bursitis. * History of injection and/or ablation treatments treatment in the affected foot up to one month previous to study participation. * History of nerve excision due to Morton s neuroma in the location to be treated with RTX. * Active cutaneous disease, inflammation or infection at the anticipated site of study drug injection. * Has diabetes mellitus or peripheral vascular disease whether poorly managed or stable. * Has more than one Morton s neuroma in the index foot scheduled to receive the treatment intervention. * Other clinically significant condition that might interfere with study participation or greatly increases safety risk to the subject, as judged by the study investigator. * Concurrent treatment with another investigational drug or other intervention within last month. * Cognitive or language difficulties that would impair comprehension or completion of the assessment instruments.