Can I Take Glycine with Repatha (Evolocumab)?

What Repatha Does

Repatha (evolocumab) is a fully human monoclonal antibody that targets PCSK9, a protein that otherwise degrades LDL receptors on liver cells. By blocking PCSK9, evolocumab leaves more LDL receptors on the hepatocyte surface, which pulls more LDL cholesterol out of circulation.

In the FOURIER trial (N=27,564, median follow-up 2.2 years), evolocumab added to statin therapy reduced LDL-C by roughly 59% from baseline and reduced the composite risk of major adverse cardiovascular events by about 15% relative to placebo in patients with established atherosclerotic cardiovascular disease (ASCVD) ([1]). Injection site reactions occurred in a small minority of patients and were not a major driver of discontinuation ([1]).

Evolocumab is FDA-approved for:

• Heterozygous familial hypercholesterolemia (HeFH)
• Homozygous familial hypercholesterolemia (HoFH), typically at the higher 420 mg monthly dose
• Established ASCVD, as an adjunct to diet and maximally tolerated statin therapy

Cholesterol guidelines from the American Heart Association and American College of Cardiology support adding a PCSK9 inhibitor for ASCVD patients whose LDL-C remains elevated on maximally tolerated statin therapy ([3]). That is a paraphrase of the guideline's general position, not a verbatim quotation, and the exact wording and current version of the recommendation should be checked against the source document before it is used in patient materials.

Why the Usual Interaction Framework Doesn't Apply

Most drug-supplement interactions happen because a supplement induces or inhibits a CYP450 enzyme (CYP3A4, CYP2C9, CYP2C19, CYP2D6) that also metabolizes a drug, or because it displaces a highly protein-bound drug from albumin. Evolocumab is a large protein (approximately 144 kDa) cleared like other immunoglobulins, through proteolytic breakdown in the reticuloendothelial system, not through the liver's cytochrome P450 pathway. The FDA label states that no dedicated drug interaction studies were conducted and that no dose adjustment is needed based on co-administered lipid-lowering therapy ([2]). Glycine is absorbed through amino acid transporters (SNAT1, SNAT2) and does not meaningfully inhibit or induce those CYP enzymes. At the molecular scale involved, protein-binding displacement is not a relevant mechanism for a monoclonal antibody. Together, these facts are why a pharmacokinetic interaction is not expected, even though the combination itself has not been formally tested.

What Glycine Is and Why People Take It

Glycine is the simplest amino acid and is considered conditionally non-essential: the body makes a meaningful amount endogenously, but supplemental or dietary intake is used to reach higher total demand ([4]). People take glycine supplements for sleep quality, collagen and connective tissue support, and possible effects on glucose handling.

Sleep

A small randomized crossover study (N=11) found that 3 g of oral glycine taken about an hour before bed improved subjective and objective measures of sleep onset and next-day fatigue compared with placebo ([5]). This is a small trial and should be read as suggestive, not definitive, but it is consistent with glycine's known role as an inhibitory neurotransmitter in the spinal cord and brainstem and its mild effect on peripheral vasodilation and core temperature.

Glucose and Insulin

Older metabolic research found that an oral glycine load produces an acute change in plasma insulin and glucose handling compared with an equivalent glucose load alone ([6]). This supports a plausible mechanism by which glycine could influence insulin sensitivity, but it is an acute physiological study, not a long-term trial of glycine supplementation improving HbA1c in people with diabetes. If you have seen a specific figure online for how much glycine lowers HbA1c over weeks or months, that number is not something this source material can confirm, and it should be verified against a real clinical trial before being repeated as fact.

This connects to Repatha patients indirectly. Most people on evolocumab are also on a high-intensity statin, and statins carry a modest, well-documented increase in new-onset type 2 diabetes risk, with a pooled analysis estimating an odds ratio near 1.09 ([7]). Whether glycine meaningfully offsets that risk in statin-treated patients has not been studied directly. It is a reasonable thing to mention to your prescriber, not a reason to avoid either therapy.

Collagen and Connective Tissue

Glycine makes up roughly one-third of the amino acid residues in collagen, which is why it is commonly paired with vitamin C and proline for skin, tendon, or joint support at doses of 5 to 15 g per day. This use case has no known interface with evolocumab's mechanism.

Blood Pressure

A handful of small studies and reviews have looked at glycine and blood pressure, with modest reductions reported in some trials ([9]). The size of that effect, and whether it is consistent, is not well established from the material available here. Patients on antihypertensives should still mention any new supplement to their prescriber as routine practice, independent of Repatha.

Is There a Pharmacokinetic Interaction?

Based on the mechanisms above, there is no established pharmacokinetic interaction between glycine and evolocumab. Evolocumab is delivered subcutaneously and reaches peak serum levels roughly 3 to 4 days post-injection through lymphatic uptake; glycine is taken orally and peaks in plasma within 1 to 2 hours. The two do not share an absorption route, a metabolic enzyme, or a plasma protein-binding interaction. No dose-separation window is required between an evolocumab injection and a glycine dose.

Is There a Pharmacodynamic Overlap?

This is the part of the picture that is genuinely uncertain rather than reassuring by mechanism alone, because it depends on whether two agents affecting related physiology in different patients actually behaves the same way when combined. Here is what can and cannot be said with the evidence at hand:

• Evolocumab lowers LDL-C by 50 to 65% through PCSK9 blockade and LDL receptor upregulation. No published trial has evaluated whether glycine blunts or enhances that receptor-level effect, and there is no mechanistic reason to expect it does.
• Small studies suggest glycine may have modest, separate effects on lipid markers, glucose handling, or blood pressure. Where this article cited specific numbers in an earlier draft (a specific milligram-per-deciliter cholesterol reduction, a specific HbA1c percentage), those figures could not be traced to a verifiable source in this review and have been removed rather than repeated as fact. If a specific number matters for a patient conversation, it should be pulled from a checked primary source at the time of use, not from a supplement retailer's health claim.
• Directionally, any real effect of glycine on lipids or glucose would trend toward cardiovascular benefit rather than working against evolocumab's purpose. That directional reasoning is not the same as trial-confirmed additive benefit.

Evidence-Status Assessment: Glycine and Evolocumab

Reference this table to help guide discussions with your prescriber or pharmacist, but it should not replace direct medical consultation. When a finding is labeled "Not established," this indicates the evidence for evolocumab has not been assessed in this analysis, rather than confirming safety concerns.

Practical Guidance

Glycine Dosing Commonly Used in Practice

• Sleep: around 3 g, 30 to 60 minutes before bed
• Glycemic or general use: 3 to 5 g with meals
• Connective tissue support: 5 to 10 g daily, sometimes split into two doses

No timing separation from Repatha injections is needed, since the two do not share an absorption or metabolic pathway.

Repatha Administration

Evolocumab is given as 140 mg subcutaneously every 2 weeks, or as 420 mg monthly (three 140 mg injections given within 30 minutes), using the SureClick autoinjector or the Pushtronex on-body infusor. Glycine can be taken on any day of the injection cycle.

Situations That Call for Extra Caution

• Chronic kidney disease (stage 3 to 5): Glycine and its metabolites are partly cleared renally. Formal safety data on high-dose glycine (above roughly 5 to 10 g per day) in CKD patients is limited, and a specific creatinine effect could not be confirmed from the sources used in this review. Patients with reduced kidney function should ask their nephrologist or cardiologist before using glycine above a low dose.
• Non-ketotic hyperglycinemia: A rare inborn error of glycine metabolism, diagnosed in infancy. Adults with this condition would already know their diagnosis and should not supplement with glycine.
• Pregnancy: The Repatha label notes limited human pregnancy data and asks patients to inform their prescriber of pregnancy ([2]). Glycine is generally recognized as safe at dietary intake, but high-dose supplementation during pregnancy alongside a biologic agent has not been formally studied. This combination should be discussed directly with the managing obstetrician and cardiologist rather than decided from a general reference page.

Monitoring

• Lipid panel: Standard practice after starting evolocumab is a fasting lipid panel around 4 to 12 weeks, then periodically based on stability. If LDL-C response looks blunted, the first steps are checking adherence and ruling out secondary causes of hypercholesterolemia, not assuming glycine is responsible.
• Glucose and HbA1c: Patients on a high-intensity statin plus evolocumab already have a reason for periodic glucose monitoring given statin-associated diabetes risk ([7]). If you use glycine at higher doses, mention it so any glucose trend is interpreted with full context, rather than expecting glycine to produce a specific measurable change.
• Injection site reactions: Evolocumab's most common side effect is a local injection site reaction; glycine has no known effect on this.

Special Populations

Familial hypercholesterolemia (HeFH/HoFH): Patients often use additional agents such as ezetimibe or bempedoic acid alongside evolocumab. Glycine has no documented interaction with these either, based on the same absence of a shared metabolic pathway.

Older adults: This group commonly uses glycine for sleep or joint support and is also well represented among evolocumab users given ASCVD prevalence. Reduced renal clearance with age is a reasonable argument for staying at or below moderate glycine doses, though no age-based dose adjustment applies to evolocumab itself ([2]).

A Note on "Natural" and Perceived Safety

Glycine occurs naturally in collagen-containing foods (bone broth, skin-on poultry, gelatin) at roughly 2 to 5 g per serving, which leads some people to assume supplemental doses are automatically inert. That is a reasonable working assumption for glycine specifically, since no clear toxicity signal has emerged in the doses used in clinical research (roughly 3 to 15 g per day), but it is not a universal rule for supplements. The active variable is dose: a nutrient consumed at food-level amounts and the same compound taken at pharmacologic doses can behave differently in the body. Regulatory reviews of amino acid intake, including glycine, have generally not set a firm upper intake limit, though that reflects a lack of observed harm in available studies rather than proof of safety at any dose ([11]). Confirm the current version of that guidance before treating it as settled.

What to Bring to Your Next Appointment

• The glycine dose and frequency you use
• Why you are taking it
• How long you have used it
• Any other supplements, since the interaction picture changes if you combine several

A fasting lipid panel around 8 to 12 weeks after starting evolocumab remains the most concrete monitoring step for PCSK9 inhibitor therapy regardless of supplement use.