Intervention: Acetaminophen
Trial phase: Phase 4
ATC code: N02AJ01 | N02AJ06 | N02AJ13 | N02AJ17 | N02BE01 | N02BE51 | N02BE71
SMILES: CC(=O)Nc1ccc(O)cc1
Sex: All
Age groups: Adult | Older Adult
Healthy volunteers: Accepts Healthy Volunteers
Participants at risk: 7
Group description: All the participants in this arm received test product (containing 500 mg of paracetamol). All the participants took 2 tablets at once orally with 200 mL of water.
Eligibility criteria:
Inclusion Criteria

Demonstrates understanding of the study procedures, restrictions and willingness to participate as evidenced by voluntary written informed consent and has received a signed and dated copy of the informed consent form.
Aged between 18-65 years.
Participant is male or female.
Understands and is willing, able and likely to comply with all study procedures and restrictions.
Adequately completes cognition and mobility familiarisation tasks in the opinion of the investigator.
Good general and mental health with, in the opinion of the investigator or medically qualified designee: No clinically significant and relevant abnormalities in medical history or upon physical examination; absence of any condition that might impact on the participant's safety or wellbeing or affect the individual's ability to understand and follow study procedures and requirements; BMI >18.5 and <30 kg/m2
VISIT 1 ONLY - Has experienced a minimum of two recurrent, acute pain episodes within the past 3 months or is currently suffering from a flare up episode of recurrent, acute pain; VISIT 2 ONLY - A score ≥5 to question 6 (rated on scale 0-10) on the Brief Pain Inventory - Short Form and participants presenting with only one of the following pain types: Joint (Knee, Hip); Back; Headache; Period.

Exclusion Criteria

Women who are pregnant (Visit 1), women of child bearing potential who test positive on a urine pregnancy test (Visit 1 or Visit 2), females of non-child bearing potential will not be required to complete urinary pregnancy test, post-menopausal females not requiring a pregnancy test will be defined as: Age ≥ 50 years with spontaneous cessation of menses for 12 or more months or age < 55 years and spontaneous menses within the past 1 year, but currently amenorrheic.
Women who are currently breast-feeding.
In the opinion of the medical designee, participant suffers from medical condition(s) that may be aggravated due to testing procedures or may impact the interpretation or integrity of data. Conditions related to renal, hepatic, respiratory, blood, immune systems or heart dysfunction will be considered.
Participant is colour blind.
Current (within 14 days of the start of the study) or regular use of any prescription, over-the-counter (OTC), herbal medicine unless the medication has been approved by the study physician. OTC analgesics for pain relief and vitamin supplements are permitted only until 48 hours prior to study visits; Current or in the 30 days prior to dosing use of any drug, food, herbal product, or dietary supplement known to induce or inhibit hepatic drug metabolism (e.g. barbiturates, theophylline, cimetidine, or erythromycin) ;Use of analgesics and anti-inflammatory drugs 48 hours prior to dosing at Visit 2; Known to be taking any other medication which could counteract with paracetamol and/or caffeine; Current or past use of anti-depressants or psychoactive drugs within the previous 2-years.
Known or suspected intolerance or hypersensitivity to the study materials (or closely related compounds) or any of their stated ingredients.
Positive breath alcohol test at Visit 2 and positive urine drugs of abuse test at Visit 2.
Participation in another clinical study (including cosmetic studies) or receipt of an investigational product within 7 days of the screening visit or previous participation and randomization in this study.
Participant has excessive frequent caffeine intake equivalent to 6 cups of brewed coffee or 12 cups of tea per day; Unwilling to abstain from any caffeine products from 4 hours prior to the visit on assessment days (Visit 2 and 3); Current Smoker (or regular nicotine consumption): Participant smokes more than 3 cigarettes per day (or equivalent for e-cigarettes, chewing tobacco or pipes). Investigator will ensure there is no impact of withdrawal effect from those with nicotine dependence; Current Alcohol Consumer: Participant consumes greater than 21 units of alcohol per week (male) and 14 units per week (female) (e.g. Spirit 25ml = 1 unit / AlcoPop 275ml = 1.5 unit / Bottle of beer 330 ml = 1.7 unit / Glass of wine 175ml = 2.1 unit / Pint of beer 568 ml = 3 unit).
Members of the study site staff or members of their immediate family.
Any participant who in the opinion of the investigator should not take part in this study.