Efficacy and tolerability of diclofenac potassium + thiocolchicoside versus diclofenac potassium in patients with acute severe low back pain

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What is this study about?

The study focuses on adults who are experiencing low back pain, a condition where the muscles and joints in the lower spine cause discomfort that can limit movement. The pain targeted is sudden in onset (acute) and strong (severe). Participants receive one of three options: a tablet that combines diclofenac (a medication that reduces inflammation and pain) with thiocolchicoside (a drug that helps relax muscles), a tablet containing only diclofenac marketed as Cataflam, or an inactive tablet called placebo.

The purpose of the study is to determine whether the combination tablet provides better pain relief and is well tolerated compared with the single‑ingredient tablet and placebo. Over a period of about one week, participants take the assigned tablets at regular intervals and record their pain levels and any need for extra pain medication. Simple physical tests, such as reaching toward the floor, are performed at the start and at the end of the week to see if movement improves.

1 baseline visit

after joining, attend the first visit where medical history and current low back pain are documented.

provide written consent and undergo basic physical measurements that will be used for later comparison.

2 randomization

based on a computer‑generated list, be assigned to one of three groups: the test medication group, the comparator group, or the placebo group.

receive a sealed medication pack that corresponds to the assigned group.

3 start of study medication

begin taking the study tablets on the same day as the baseline visit.

the medication schedule lasts for seven consecutive days.

if assigned to the test medication group, take two film‑coated tablets containing diclofenac potassium and thiocolchicoside by mouth each day.

if assigned to the comparator group, take three sugar‑coated tablets containing diclofenac potassium by mouth each day.

if assigned to the placebo group, take the same number of tablets as indicated for the other groups, using either placebo yellow or placebo red, by mouth each day.

4 daily pain recording

each day, complete a pain diary that asks for the intensity of low back pain at several time points after taking the study tablet.

record the scores in the provided notebook or electronic form as instructed.

5 use of rescue medication

if pain remains severe, a rescue medication may be taken.

the rescue option is paracetamol (depon maximum 1000 mg) tablets; take up to three tablets by mouth as needed.

note each rescue dose in the pain diary.

6 interim monitoring

study staff may review the completed pain diary and inquire about any adverse effects during the treatment period.

no additional medication adjustments are made unless safety concerns arise.

7 final assessment (day 7)

return to the clinic on day seven for the final visit.

hand in the completed pain diary and undergo the same functional measurement performed at baseline (finger‑to‑floor distance).

receive a brief safety check and study completion documentation.

8 study completion

after the final assessment, the participation in the trial ends.

no further study medication is taken after day seven.

Who Can Join the Study?

You are 18 years old or older.
You have acute low back pain that began within the past 7 days and is very severe, meaning you rate it at 75 mm or higher on a 100‑mm line called the visual analog scale (VAS)—a simple method where you mark how much pain you feel.
You can understand what the study asks you to do and are able to return for the required follow‑up visits.
You agree to give voluntary written informed consent, which is a written agreement that you understand the study and choose to join before any procedures begin.

Who Cannot Join the Study?

Severe allergy (hypersensitivity) to any ingredient in the study drug or its inactive parts.
Having taken NSAIDs (non‑steroidal anti‑inflammatory drugs) or muscle‑relaxing medicines too recently – you must wait long enough for those drugs to leave your body (about five times the time it takes for half of the drug to disappear, called the elimination half‑life).
Being enrolled in another clinical study that used investigational medicines or devices within the past 30 days.
Having a current stomach or intestinal sore, bleeding, or a hole (active gastric or intestinal ulcer, bleeding or perforation).
Being unable or unwilling to follow the study’s rules and procedures.
Not agreeing to let the study keep and share your medical information in a coded (pseudonymous) form.
Being legally unable to give consent (for example, under guardianship).
Being held in a legal detention or correctional facility.
Having a history of two or more serious stomach ulcers or bleeding episodes (recurrent peptic ulcer/haemorrhage).
Severe liver failure (hepatic failure) or other serious liver disease.
Severe kidney failure (renal failure) defined as a glomerular filtration rate (GFR) less than 15 mL/min/1.73 m², a test that measures kidney function.
Having very weak muscles or limp paralysis (flaccid paralysis or muscle hypotonia).
Being pregnant, breastfeeding, or not using a highly effective birth‑control method during the study and for one month after it ends.
Having previously had stomach or intestinal bleeding or a hole caused by NSAID use.
Having asthma, severe allergic reactions (angioedema, hives, or acute nasal inflammation) triggered by aspirin or other NSAIDs.
Having serious heart or blood‑vessel disease, such as established congestive heart failure (NYHA class II‑IV), coronary artery disease, peripheral arterial disease, or stroke‑related disease.
Having blood‑clotting problems, bleeding disorders, or other blood abnormalities.
Having hepatic porphyria, a rare liver disorder that affects pigment production.
Being a frail older adult (very weak elderly patient).
Weighing less than 50 kg (about 110 lb).
For men: not willing to use a condom or ensure that a partner of child‑bearing potential uses a highly effective birth‑control method during treatment and for three months after the last dose.
Having severe active liver disease (severe hepatocellular insufficiency/failure or decompensated liver disease).
Using other treatments for low back pain (such as oral medicines, acupuncture, heat therapy, yoga, or starting physiotherapy) within the two months before the study begins.
Having other back‑related problems that could affect study measurements.
Having other medical conditions that could interfere with study assessments.
Having neurological (brain or nerve) or psychiatric (mental health) conditions.
Taking any medication that the study lists as prohibited.

Where you can join this trial?

Verified and Recommended Sites

No sites found in this category

Verified Sites

Site Name	City	Country	Status
Kat Attica General Hospital	Kifissia	Greece

Other Sites

Site Name	City	Country
MedCare Clinic	Nicosia	Cyprus
General Hospital of Nikaia-Piraeus, “Agios Panteleimon”	Piraeus	Greece
Peiraiko Therapeftirio S.A.	Piraeus	Greece

Trial status

Country	Status	Recruitment Start
Cyprus	Recruiting	29.05.2026
Greece	Not yet recruiting	29.05.2026

Trial locations

Investigated drugs:

Diclofenac + Thiocolchicoside tablets – This is a fixed‑dose combination tablet that contains two active ingredients. Diclofenac is a non‑steroidal anti‑inflammatory drug (NSAID) that helps reduce pain and inflammation. Thiocolchicoside is a muscle‑relaxing agent that can relieve muscle stiffness and spasms. In the trial the tablet was taken by mouth and was tested to see if it works better than a single‑ingredient NSAID for severe low back pain.

Paracetamol tablets (DEPON MAXIMUM) – Paracetamol is a common pain‑relieving and fever‑reducing medicine. In this study it was given to all participants as a background medication to provide basic pain relief, so the researchers could evaluate the added benefit of the test and comparator drugs.

Cataflam tablets – Cataflam contains diclofenac potassium, an NSAID that reduces pain and inflammation. It was used as the active comparator in the trial, allowing a direct comparison between the single‑ingredient diclofenac and the combination product that also includes a muscle relaxant.

Low back pain – Low back pain is discomfort or aching in the area of the lower spine. It often begins gradually after activities that strain the back, such as lifting or prolonged sitting. The pain can increase with movement and may spread to the hips or thighs. Over several days, the intensity may fluctuate, sometimes becoming more pronounced after physical exertion. In some cases, the discomfort can linger, leading to a feeling of stiffness that improves with gentle activity.

Trial ID:

2025-523153-33-00

Protocol code:

DITH-II/VER

Trial Phase:

Therapeutic confirmatory (Phase III)

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Efficacy and tolerability of diclofenac potassium + thiocolchicoside versus diclofenac potassium in patients with acute severe low back pain

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?