How semaglutide is metabolised and cleared by your body

Why a weekly injection works: the albumin-binding trick

The short answer to why semaglutide only needs to be injected once a week lies in deliberate molecular engineering. Natural GLP-1, the gut hormone semaglutide mimics, has a half-life measured in minutes, it is degraded almost immediately by an enzyme called DPP-4. Novo Nordisk altered the semaglutide molecule in two important ways: first, substituting a single amino acid to resist DPP-4 breakdown; second, attaching a long-chain fatty acid via a linker. That fatty acid causes semaglutide to bind reversibly to albumin, a transport protein abundant in the blood. Albumin-bound semaglutide circulates for days before being slowly released and degraded. The practical result is a half-life of around seven days and therapeutically stable concentrations between doses. You can read more about what this steady exposure does to weight regulation on the does semaglutide change your metabolism page, which addresses a related question our prescribers hear often. One common misconception is that semaglutide is processed by the liver in the same way as many oral drugs, it is not. The liver's cytochrome P450 enzymes, responsible for metabolising most small-molecule medicines, play no significant role here. The breakdown happens instead through nonspecific proteolytic enzymes distributed across body tissues.

The actual metabolic pathway: proteolysis and elimination

Semaglutide's metabolic fate has been studied formally as part of the regulatory submissions reviewed by the MHRA and the EMA. The medicine is broken down by endopeptidases and exopeptidases (enzymes that cleave peptide bonds) releasing fragments and fatty-acid metabolites. Those fragments are small enough to be filtered by the kidneys and passed in urine, or excreted via bile into faeces. Crucially, this pathway is distributed enough that neither severe renal impairment nor moderate hepatic impairment dramatically changes overall exposure in most people, according to the Wegovy summary of product characteristics published on the eMC. A prescriber still reviews renal and liver status during consultation, because individual clinical context matters, but the absence of a single dominant organ for clearance makes semaglutide's pharmacokinetics relatively predictable. This predictability is part of why Wegovy reached a once-weekly dosing schedule across every strength from 0.25 mg up to the newer 7.2 mg maintenance dose approved by the MHRA in early 2026. If you are weighing up what Wegovy involves practically, our Wegovy price comparison page provides context on the cost landscape for private treatment in the UK.

Oral semaglutide: same metabolism, different absorption challenge

The MHRA approved the Wegovy tablet (the first oral GLP-1 medicine licensed in the UK for weight management) in June 2026. Its metabolic fate once absorbed is identical to the injection; the engineering challenge was getting a peptide molecule across the stomach lining intact. Peptides are normally destroyed by stomach acid and digestive enzymes before absorption. Novo Nordisk co-formulated semaglutide with an absorption enhancer called SNAC (sodium N-[8-(2-hydroxybenzoyl)amino]caprylate), which temporarily raises the local pH around the tablet as it dissolves and facilitates absorption through the gastric mucosa. This is why the tablet must be taken on an empty stomach with a small amount of plain water and why food or other drinks too soon afterwards blunts absorption. The MHRA notes that trial participants who followed the administration instructions fully achieved an average weight reduction of around 17% over 64 weeks, compared with roughly 13.6% across the full trial population regardless of adherence, a difference explained almost entirely by consistent absorption. After crossing the stomach wall, SNAC dissociates and semaglutide enters the circulation, binds albumin, and is metabolised and eliminated exactly as described above. Our semaglutide metabolism page goes deeper on the biological mechanisms if you want the fuller picture. The does Wegovy affect metabolism page covers downstream effects on energy expenditure, which is a separate question from how the drug itself is cleared. The NHS medicines page for semaglutide covers side effects and interactions in patient-level terms and is a sound first reference alongside the prescriber's own assessment.

What this means in practice, and where a prescriber fits in

Understanding semaglutide's metabolism has a few direct practical implications. Because it is not cleared by CYP450 enzymes, the interaction profile differs from many common medicines. That said, the slowed gastric emptying that semaglutide produces can reduce peak absorption of other oral medicines taken at the same time, worth raising with a prescriber if you take thyroid hormones, statins, or antibiotics that depend on rapid absorption. The long half-life also means that stopping the medicine does not produce an immediate washout; concentrations fall gradually over several weeks after the last dose. For anyone considering starting treatment, the relevant point is simpler: the pharmacokinetics were designed so that you do not need to think about the drug's behaviour between doses. You inject or swallow once, and the albumin-binding does the rest until the following week. Whether you are curious about whether semaglutide affects long-term metabolic rate, or ready to explore treatment, our prescribers work through your circumstances individually. You can also browse our treatment options to understand what a consultation with us involves. If you have questions before you start, our FAQ page covers the ones we hear most.