Inclusion Criteria:
* Inpatient setting (discharge possible, if patient returns for End of Study Visit)
* Diagnosis of metastatic or locally advanced cancer
* Cancer pain as defined by IASP (International Association for the Study of Pain)
* Cancer pain therapy with opioids indicated for pain management or start thereof at baseline (drug, dose, and route at treating physician's discretion)
* Average daily pain intensity ≥ 3 on NRS (Numeric Rating Scale)
* Ability to swallow oral medication
* Informed Consent as documented by signature
Exclusion Criteria:
* History of allergy or allergy-like symptoms (bronchospasm, urticaria or severe cutaneous adverse reactions (SCARs)) or hypersensitivity to dipyrone (or other pyrazolones or pyrazolidines) or ibuprofen (or other Non-steroidal anti-inflammatory drug incl. acetylsalicylic acid)
* Moderate to severe renal insufficiency (creatinine-eGFR (estimated Glomerular Filtration Rate) \<45 ml/min)
* Severe heart failure (New York Heart Association class III-IV)
* Severe hepatic impairment (liver cirrhosis with ascites) or hepatic porphyria
* History of agranulocytosis induced by dipyrone (or other pyrazolones or pyrazolidines)
* Active gastric and/or duodenal ulcers or bleeding
* History of recurrent gastric and/or duodenal ulcers or gastrointestinal bleeding (≥2 distinct episodes of proven ulceration or bleeding) or increased tendency to bleeding
* Third trimester of pregnancy
* Breastfeeding
* G6PD deficiency
* Inflammatory bowel disease (e.g., Crohn's disease, ulcerative colitis)
* Intrathecal or epidural opioids or local or regional anesthetic therapy
* Additional second opioid for co-analgesic effects or other reasons (e.g., methadone, buprenorphine)
* Initiation of therapy with transdermal therapeutic system (TTS) opioid \<48 hours before start of IMP
* Use of non-opioids with long half-life (i.e., acemetacin, celecoxib, etodolac, etoricoxib, ketorolac, naproxen, piroxicam, tenoxicam)
* Pain unrelated to cancer (e.g. chronic non-cancer pain \[CNCP\], postoperative, particularly following coronary artery or cardiopulmonary bypass surgery)
* Inability to follow study procedures or adhere to protocol (e.g., due to language problems, psychological disorders, dementia)
* Inability to abstain from other non-opioids (apart from IMP (Investigational Medicinal Product)) during study participation
* Participation in any interventional study targeted at pain management
* Participant is a family member or employee of the investigator
