Table 1 Eligibility criteria

Inclusion criteria

Patients are eligible for the trial if all of the following apply:

1.Must be able to provide full informed consent.

2.Male or female patients ≥ 16 years of age.

3.Patients must fulfil the following:

i)Genetically proven diagnosis of mitochondrial disease

ii)Evidence of mitochondrial myopathy as confirmed by the investigator

4.Able and willing, in the opinion of the investigator, to comply with all trial requirements.

5.Willing for their GP and Specialist (if applicable), to be informed of their participation in the trial.

6.Be on a stable dose of any current regular medication for at least four weeks prior to trial entry.

Exclusion criteria

Patients are excluded from the trial if any of the following apply:

1.Patients who are currently participating or have participated in a clinical trial of an investigational medicinal product within the 12-week period prior to the date of informed consent.

2.Patients who have had an elective or emergency admission to hospital within the 4-week period prior to the date of informed consent.

3.Patients with other known uncontrolled medical problems, which, in the opinion of the investigator, would preclude participation in the trial.

4.Patients who are:

a. Pregnant

b. Breast feeding

c. Of childbearing potential with a positive urine pregnancy test prior to starting trial IMP

d. Male or female of childbearing potential unwilling to abstain or to use contraception throughout the trial (postmenopausal women must be amenorrhoeic for at least 12 months to be considered of non-childbearing potential).

5.Patients with moderate to severe renal impairment (creatinine clearance via eGFR < 60 ml/min/1.73m²).

6.Patients with a screening AST, ALT or Gamma GT result of more than 3 times the upper limit of normal.

7.Patients with a platelet count of < 50 platelets/l of blood

8.Patients on treatment with methotrexate or other immunosuppressant medications.

9.Patients with active known peptic ulcer or history of recurrent ulceration.

10.Patients on treatment with warfarin, clopidogrel, regular high-dose (≥300 mg OD) aspirin or other anticoagulant medications, which in the opinion of the investigator precludes entry into the trial. Patients receiving high-dose aspirin who are able to come off aspirin for a period of 72 h prior to any muscle biopsy sample will be eligible to participate.

11.Patients with a medical history, which in the opinion of the investigator contraindicates the use of low-dose aspirin.

12.Patients who are already taking acipimox.

13.Patients who are taking niacin derivatives.

14.Patients with an elective hospital admission scheduled during the trial period, which in the opinion of the investigator would preclude participation.

15.Patients who may be allergic/unable to take any of the constituent ingredients of the IMP or placebo