This is a multi-center, randomized, double-blind clinical trial to evaluate the safety, tolerability, pharmacokinetics, and efficacy of ASKC200 in subjects with OA of the knees and determine the phase II recommended dose. Assigned doses will be applied for 60 minutes on each of four consecutive days.

Subjects will be randomized to one of the two Arms in this study: 5% ASKC200 or 1% ASKC200. All subjects will receive 4 consecutive days of treatment and will then be followed up until the Day 34 visit.

The NRS score of weekly average of average daily pain intensity (WAADPI) of the study knee should ≥ 5 and the NRS score of WAADPI of the contralateral knee should < 4 at screening.

Data will be collected from Day 1 through Day 5 and then again on Days 19 and 34 for efficacy, tolerability, and safety measures.

Inclusion Criteria:

1. Sign informed consent prior to any inspection and evaluation, and understand and follow test requirements;
2. Age 40-75 years old (including boundary value) at the time of signing the informed consent, gender is not limited;
3. Primary knee osteoarthritis was confirmed by clinical and imaging examination;
4. Knee osteoarthritis pain history ≥6 months;
5. Tibial joint X-ray within 3 months prior to drug administration showed that the tibiofemoral joint of the target knee was graded Kellgren-Lawrence II or III;
6. Before the first medication, the WAADPI NRS score of the study knee was ≥5, and the WAADPI NRS score of the contralateral knee was <4;
7. Be willing to discontinue the use of nonsteroidal anti-inflammatory drugs, acetaminophen, and other pain medications, and only use the acetaminophen provided in the study for emergency treatment of knee osteoarthritis pain during the study period;
8. Body mass index (BMI) ≤40.0 kg/m2.

Exclusion Criteria:

1. Secondary arthritis caused by other causes;
2. The study knee has other knee pathologic findings confirmed by clinical evaluation or imaging
3. There are other conditions that can cause study knee pain or other physical pain;
4. Other medications for osteoarthritis were used within 1 week prior to the first dose;
5. Patients with chronic pain in other parts of the body requiring long-term oral analgesic therapy, or those requiring combined treatment with systemic glucocorticoids;
6. Open knee injury or knee surgery occurred in the study knee within 6 months before the first medication; Or have had any major surgical procedures within 3 months prior to the first medication;
7. The study knee has received intra-articular injection treatment (such as steroids or sodium hyaluronate, etc.) within 3 months before the first medication;
8. Received physical therapy for study knee osteoarthritis (such as electrotherapy or acupuncture) within 3 months before the first medication;
9. Used any capsaicin-containing product or non-steroidal anti-inflammatory drug on the knee within 2 weeks prior to the first administration;
10. Have An open wound, skin erythema or edema, skin infection, or any other skin lesion in the study knee prior to initial administration;
11. A history of alcohol or drug dependence within 12 months prior to the first administration or a positive urine drug test during the screening period.