Inclusion Criteria
1. Age 18-85 years at consent.
2. Groups:
* Healthy controls: Medically healthy; no clinically significant findings in history, exam, labs, vitals, or 12 lead ECG (per investigator).
* Hepatic impairment: Chronic (≥6 months), stable; documented Child Pugh B (Group 2) or C (Group 1).
3. Stable concomitant regimen ≥2 weeks before screening (Groups 1-2).
4. T2DM allowed if HbA1c \<10% and no severe hypo/hyperglycaemia or hospitalisation within 6 months.
5. Body weight ≥50 kg; BMI 18-42 kg/m².
6. Sex assigned at birth (male/female); contraception per local regulations. Females of child bearing potential: negative pregnancy tests and condoms plus one highly effective method through 54 days post last dose. Males: condom use; no sperm donation through 54 days post last dose.
7. Written informed consent; separate consent for optional genomics.
Exclusion Criteria
Healthy controls only:
1. Any clinically significant disease; Diabetes;
2. lab values i) ALT/AST/ALP \>1.5×ULN; ii) WBC/platelets \<LLN; iii) haemoglobin \<11.0 g/dL (female) or \<12.0 g/dL (male); aPTT or PT/INR \>1.2×ULN; iv) total bilirubin \>1.5×ULN (or Gilbert's);
3. abnormal resting vital signs i) SBP \>150 or \<90 mmHg, ii) DBP \>95 or \<50 mmHg, iii) pulse ≥100 or ≤45 bpm;
4. QTcF \>450 ms or clinically significant ECG abnormalities;
5. severe allergy/hypersensitivity;
6. major surgery within 30 days;
7. pancreatitis or pancreatic enzymes \>2×ULN;
8. triglycerides \>500 mg/dL (5.6 mmol/L);
9. calcitonin \>50 ng/L (50 pg/mL);
10. severe vitamin D deficiency (\<12 ng/mL, 30 nmol/L);
11. low corrected or ionised calcium;
12. HIV positive; HBV surface/core Ab or HCV Ab positive; drug/alcohol abuse within 1 year.
Hepatically impaired only:
13. Unstable medical/psychological conditions or uncontrolled systemic disease;
14. eGFR \<50 mL/min/1.73 m² (CKD EPI 2021);
15. Abnormal resting vital signs i) SBP \>160 or \<100 mmHg, ii) DBP \>110 or \<65 mmHg, iii) pulse ≥100 or ≤50 bpm;
16. platelets \<35×10⁹/L; neutrophils \<1.2×10⁹/L; haemoglobin \<85 g/L; HbA1c ≥10%;
17. oesophageal banding within 3 months or GI bleeding within 6 months;
18. ascites requiring paracentesis and albumin ≤4 week intervals; paracentesis within 30 days;
19. fluctuating/worsening hepatic function during screening; hepatocellular carcinoma;
20. acute liver disease due to infection/drug; hepatic impairment due to non liver disease;
21. biliary obstruction or non parenchymal causes; hepatic encephalopathy Grade ≥2;
22. functioning organ transplant or anticipated within 2 months; prior porto systemic shunt/TIPS;
23. QTcF \>480 ms or clinically significant ECG abnormalities;
24. pancreatitis or pancreatic enzymes \>2×ULN;
25. triglycerides \>500 mg/dL (5.6 mmol/L); calcitonin \>50 ng/L (50 pg/mL); severe vitamin D deficiency (\<12 ng/mL, 30 nmol/L); ionised calcium \<LLN;
26. neoplastic disease within 10 years (except adequately treated BCC/SCC or in situ cervical); MEN2 or medullary thyroid carcinoma (personal or first degree relative); significant gastric emptying abnormality;
27. HIV positive; HBV surface/core Ab or HCV Ab positive (may be included if HBV DNA or HCV RNA negative on follow up); drug/alcohol abuse within 1 year.
28. Exposure to a new chemical entity within 30 days or 5 half lives (whichever longer) before intervention; prior exposure to AZD9550 or AZD6234;
Prior/concomitant therapy:
Healthy controls:
29. use of prescription/non prescription/supplements within 7 days (or 14 days for enzyme inducers) or 5 half lives before intervention unless judged non interfering; current oral contraceptives or oestrogen HRT.
Hepatically impaired:
30. prohibited-weight loss medicines (including GLP 1), agents causing significant weight gain (e.g., systemic glucocorticoids, antipsychotics), GLP 1 RAs for diabetes, QT prolonging/prokinetic agents, oral contraceptives for contraception; restricted-short systemic glucocorticoids (≤7 days), 5HT 3 antiemetics at lowest effective dose, combined oral contraceptives for non contraceptive indications. If diabetes develops and requires insulin/SU/GLP 1 RA, discontinue from study.
Other:
31. prior enrolment in this study (screened without dosing permitted). Positive drugs of abuse and/or alcohol screen (except prescribed meds in hepatic impairment); recent blood products/donation per protocol thresholds; employees or close relatives; vulnerable populations; unlikely to comply (investigator judgement).
