Safety, Tolerability and Clinical Effect of Danirixin in Adults With Influenza

Inclusion Criteria

• Between 18 and 64 years of age inclusive, at the time of signing the informed consent;
• Onset of influenza-like illness symptoms within 48 hours prior to study enrollment. Onset of symptoms is defined as the time when the subject's temperature was measured as elevated (>=38.0°C [>=100.4°F]) OR the time when the subject first experienced at least one symptom (cough, sore throat, nasal congestion, headache, feeling feverish, body aches and pains, or fatigue);
• Subjects have an oral temperature >=38.0°C (>=100.4°F) at screening visit or history of feeling feverish within the 24 hours prior to screening visit;
• At least one respiratory symptom (cough, sore throat, nasal congestion) and at least one systemic symptom (headache, body aches and pain, fatigue) due to influenza infection;
• A positive influenza rapid antigen test;
• Body weight >60 Kilogram (kg) for men and >45 kg for women; and Body Mass Index (BMI) between 19 to 35 kilogram per meters squared (kg/m^2), inclusive;
• Male or Female subjects could be eligible if :

Male subjects with female partners of child-bearing potential must comply with the following contraception requirements from the time of first dose of study medication until at least 36 hours (five half-lives) of study medication after the last dose of study medication:

Vasectomy with documentation of azoospermia; Male condom plus partner use of one of the following contraceptive options: Contraceptive subdermal implant; Intrauterine device or intrauterine system; Oral Contraceptive, either combined or progestogen alone; Injectable progestogen; Contraceptive vaginal ring ; Percutaneous contraceptive patches; This is an all-inclusive list of those methods that meet the following GlaxoSmithKline (GSK) definition of highly effective: having a failure rate of less than 1% per year when used consistently and correctly and, when applicable, in accordance with the product label. For non-product methods (e.g., male sterility), the investigator determines what is consistent and correct use. The GSK definition is based on the definition provided by the International Conference on Harmonisation (ICH). The investigator is responsible for ensuring that subjects understand how to properly use these methods of contraception;

• Female subject: is eligible to participate if she is not pregnant (as confirmed by a negative urine human chorionic gonadotrophin [hCG] test), not lactating, and at least one of the following conditions applies

Non-reproductive potential defined as:

Pre-menopausal females with one of the following: documented Tubal ligation; Documented Hysteroscopic tubal occlusion procedure with follow-up confirmation of bilateral tubal occlusion; Hysterectomy; Documented Bilateral oophorectomy; Postmenopausal defined as 12 months of spontaneous amenorrhea (in questionable cases a blood sample with simultaneous follicle stimulating hormone [FSH] and estradiol levels consistent with menopause). Females on hormone replacement therapy (HRT) and whose menopausal status is in doubt will be required to use one of the highly effective contraception methods if they wish to continue their HRT during the study.

Reproductive potential agrees to follow one of the options listed below in the GSK Modified List of Highly Effective Methods for Avoiding Pregnancy in Females of Reproductive Potential (FRP) requirements from the time of screening, during dosing, and until at least 36 hrs after the last dose of study medication and completion of the follow-up visit.

GSK List of Highly Effective Methods for Avoiding Pregnancy in Females of Reproductive Potential (FRP) meeting GSK criteria of highly effective: having a failure rate of less than 1% per year when used consistently and correctly and, when applicable, in accordance with the product label. This list does not apply to FRP with same sex partners, when this is their preferred and usual lifestyle or for subjects who are and will continue to be abstin