Saxenda does not contain pregnenolone. The active ingredient in Saxenda is liraglutide, a glucagon-like peptide-1 (GLP-1) receptor agonist used for weight management in adults and adolescents. Pregnenolone is a steroid hormone precursor with no established role in Saxenda's formulation or mechanism of action. This article clarifies the composition of Saxenda, explains what pregnenolone is, and provides essential prescribing and safety information for patients and healthcare professionals considering this weight management medication in the UK.

Understanding Saxenda: Active Ingredient and Composition

Saxenda is not composed of pregnenolone. The active pharmaceutical ingredient in Saxenda is liraglutide, a glucagon-like peptide-1 (GLP-1) receptor agonist. Each pre-filled pen contains liraglutide at a concentration of 6 mg/mL, with the maximum daily dose being 3.0 mg administered via subcutaneous injection. Liraglutide is a synthetic peptide analogue that shares 97% structural homology with endogenous human GLP-1, a naturally occurring incretin hormone.

The formulation of Saxenda includes several excipients alongside the active ingredient liraglutide. These inactive components comprise disodium phosphate dihydrate, propylene glycol, phenol, water for injections, and pH adjusters (hydrochloric acid and sodium hydroxide). These excipients serve essential pharmaceutical functions, including maintaining solution stability, ensuring appropriate pH levels, and acting as preservatives to prevent microbial contamination throughout the product's shelf life.

Saxenda received marketing authorisation in the UK through the Medicines and Healthcare products Regulatory Authority (MHRA) for weight management. It is indicated as an adjunct to a reduced-calorie diet and increased physical activity for weight management in adults with an initial body mass index (BMI) of 30 kg/m² or greater (obesity), or 27 kg/m² or greater (overweight) in the presence of at least one weight-related comorbidity such as dysglycaemia, hypertension, dyslipidaemia, or obstructive sleep apnoea. Saxenda is also indicated for weight management in adolescents aged 12 years and above with a body weight of at least 60 kg and obesity.

There is no pregnenolone in Saxenda's formulation. Any confusion may arise from misunderstanding the drug's composition or conflating different pharmaceutical products. Patients should always verify medication ingredients with their prescriber or pharmacist if they have concerns about specific components. Importantly, Saxenda should not be used concomitantly with other GLP-1 receptor agonists.

What Is Pregnenolone and Its Medical Uses

Pregnenolone is a naturally occurring steroid hormone synthesised primarily in the adrenal glands, though it is also produced in smaller quantities in the brain, liver, skin, and gonads. As a precursor molecule, pregnenolone occupies a pivotal position in steroidogenesis—the biochemical pathway responsible for producing all steroid hormones in the human body. Through enzymatic conversion, pregnenolone serves as the parent compound from which the body manufactures cortisol, aldosterone, progesterone, oestrogen, testosterone, and dehydroepiandrosterone (DHEA).

Despite its fundamental role in human physiology, pregnenolone has no established, licensed therapeutic indication in mainstream UK medical practice. It is not approved by the MHRA as a prescription medicine for any specific condition. Some complementary and alternative medicine practitioners have promoted pregnenolone supplements for various purported benefits, including cognitive enhancement, mood regulation, and anti-ageing effects, but these claims lack robust clinical evidence from adequately powered, peer-reviewed trials.

In research settings, pregnenolone has been investigated for potential neuropsychiatric applications, including studies examining its effects on memory, schizophrenia symptoms, and post-traumatic stress disorder. However, these remain experimental areas without conclusive evidence supporting routine clinical use. The hormone's role as a neurosteroid—capable of modulating neurotransmitter systems in the central nervous system—has generated scientific interest, but translation into evidence-based therapeutics remains limited.

Pregnenolone is not licensed in the UK and is not permitted as a food supplement. Products containing pregnenolone that are available online may be unregulated and of uncertain quality, purity, and dosing consistency. Healthcare professionals in the UK generally do not recommend pregnenolone supplementation due to insufficient safety data, potential hormonal disruption, and lack of proven clinical benefit. Patients considering such supplements should discuss this with their GP or endocrinologist.

How Saxenda Works: Mechanism of Action

Saxenda exerts its therapeutic effects through liraglutide's action as a GLP-1 receptor agonist. GLP-1 is an incretin hormone naturally released from intestinal L-cells in response to food intake. By binding to and activating GLP-1 receptors distributed throughout the body—including the pancreas, gastrointestinal tract, cardiovascular system, and central nervous system—liraglutide mimics and amplifies the physiological actions of endogenous GLP-1.

The weight management effects of Saxenda operate through multiple complementary mechanisms. Centrally, liraglutide acts on GLP-1 receptors in appetite-regulating centres of the hypothalamus, reducing hunger signals and increasing satiety. This leads to decreased food intake and reduced energy consumption. Peripherally, the medication slows gastric emptying, prolonging the sensation of fullness after meals and reducing postprandial glucose excursions, although this effect may diminish over time with continued treatment. These combined effects create a negative energy balance conducive to weight loss when accompanied by lifestyle modifications.

In terms of glucose homeostasis, liraglutide enhances glucose-dependent insulin secretion from pancreatic beta cells whilst suppressing inappropriately elevated glucagon secretion from alpha cells. Importantly, this glucose-dependent mechanism means insulin secretion only increases when blood glucose levels are elevated, substantially reducing the risk of hypoglycaemia compared with some other glucose-lowering agents. This pharmacological profile explains why liraglutide at lower doses (up to 1.8 mg daily) is also licensed as Victoza for type 2 diabetes management.

The molecular structure of liraglutide includes modifications that confer resistance to degradation by the enzyme dipeptidyl peptidase-4 (DPP-4), which rapidly inactivates native GLP-1. Additionally, liraglutide's fatty acid side chain enables reversible binding to albumin, significantly extending its half-life to approximately 13 hours and permitting once-daily subcutaneous administration. This pharmacokinetic profile is entirely distinct from steroid hormones like pregnenolone, which have completely different mechanisms of action, metabolic pathways, and physiological effects.

Safety Considerations and Prescribing Information for Saxenda

Saxenda requires careful patient selection and monitoring. The UK SmPC includes important warnings about thyroid C-cell tumours observed in rodent studies (though human relevance remains uncertain). The medication should not be used during pregnancy or breastfeeding, and women of childbearing potential should use effective contraception during treatment.

Common adverse effects reported with Saxenda include gastrointestinal disturbances—particularly nausea, vomiting, diarrhoea, and constipation—which typically diminish over time as tolerance develops. The dose titration schedule (starting at 0.6 mg daily and increasing weekly by 0.6 mg increments to the maintenance dose of 3.0 mg) helps minimise these effects. Other frequently reported reactions include headache, dyspepsia, fatigue, dizziness, and injection site reactions. Hypoglycaemia risk increases when Saxenda is used concomitantly with insulin or sulphonylureas, necessitating dose adjustments of these agents. There is limited data on concomitant use with insulin in the weight management indication.

Serious but rare adverse events include acute pancreatitis, gallbladder disease (cholelithiasis and cholecystitis), and increased heart rate. Patients should be counselled to seek immediate medical attention if they experience severe, persistent abdominal pain, and treatment should be discontinued if pancreatitis is suspected or confirmed. Healthcare professionals should monitor for signs of suicidal ideation or behaviour, and patients should be advised about the risk of dehydration potentially leading to renal impairment.

According to the UK SmPC, Saxenda should be discontinued if patients have not achieved at least 5% weight loss after 12 weeks at the maintenance dose (3.0 mg daily), as continued treatment is unlikely to provide clinically meaningful benefit. Saxenda must not be used together with other GLP-1 receptor agonists.

NHS availability of Saxenda is subject to local commissioning policies, with many patients managed via specialist tier 3 weight management services. Regular monitoring includes assessment of weight loss progress, cardiovascular parameters (particularly heart rate), and screening for adverse effects. Patients should be advised that Saxenda is an adjunct to—not a replacement for—dietary modification and increased physical activity. The medication should be stored in a refrigerator before first use, then may be kept at room temperature (below 30°C) for up to one month. Patients must be trained in proper subcutaneous injection technique, rotating injection sites to prevent lipodystrophy.

Patients should report any suspected side effects to their healthcare professional or directly to the MHRA through the Yellow Card Scheme. Any concerns about medication composition, including questions about ingredients like pregnenolone (which, to reiterate, is not present in Saxenda), should be discussed with the prescribing clinician or pharmacist.

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