Unseen Effects: Potential Impacts of GLP-1 Weight Loss Medications

Unseen Effects: Potential Impacts of GLP-1 Weight Loss Medications

It's important to remember that information regarding GLP-1s might not all apply to brands available in New Zealand, and research into these drugs is continuously evolving.

Professor Rhiannon Braund, head of the University of Waikato's school of pharmacy and biomedical sciences, states that all medications come with side effects.

According to Braund, a drug that influences different areas of the body may trigger varied reactions or outcomes for individuals due to their unique physiology. Therefore, proper dosing is essential because everyone has slight differences.

Data sheets accompany all medicines, listing known side effects that range from common to rare, based on the results of clinical trials. These trials, however, represent a limited segment of the broader population.

Braund notes that clinical trials often exclude women due to the risk of harming an unborn child. Therefore, findings from these trials, often conducted on healthy males in controlled settings, may not predict all real-world side effects.

Some side effects arise from drug interactions, which are not always predictable during clinical trials. This is why Medsafe in New Zealand actively monitors medicines for side effects after they become available to the public.

According to Braund, prescribers maintain a high level of vigilance regarding potential side effects of newly introduced medications. Healthcare professionals, including nurses, doctors, and pharmacists, prioritize discussions with patients about possible side effects, especially when limited information about the medicines is available.

Semaglutide (Wegovy), dulaglutide (Trulicity), and liraglutide (Victoza, Saxenda) are available in New Zealand and prescribed for both weight loss and diabetes. Ozempic, another brand of semaglutide, is not available there.

Pharmac subsidizes dulaglutide and liraglutide for type 2 diabetes, but not for weight loss, meaning those prescribed for weight management must pay for them.

The data sheets for GLP-1s in New Zealand list potential benefits and negative side effects. Braund explains the reason for their occurrence, what you should know, and when to be concerned.

GLP-1s can provide health benefits resulting from weight loss, as well as some unexpected advantages.

Braund points out that for many individuals, the focus extends beyond physical weight to include the consequences of carrying excess weight, which can lead to various knock-on effects.

Carrying excess weight can contribute to problems such as stroke and other cardiovascular issues.

Potential Benefits of GLP-1s

Reduce risk of heart attack, stroke

Obesity increases heart attack risk by forcing the heart to work harder. GLP-1s can reduce this risk, along with stroke risk, by promoting rapid weight loss.

Reduce risk of fatty liver disease

These medications can also lower the risk of fatty liver disease, which results from fat accumulation in the liver, and lipid disorders, which involve an unhealthy balance of fats in the blood.

Lower blood pressure

GLP-1s aid in lowering blood pressure through weight loss, as excess body fat increases the heart's workload. They also enhance kidney function, promoting salt excretion and improving blood vessel function.

Reduce risk of kidney disease, diabetes-related nephropathy or kidney damage

GLP-1s may slow the advancement of kidney disease and lower the risk of kidney failure, though experts suggest nutritional support is crucial. Health tracking apps like Shotlee can help monitor nutritional intake and overall health.

Reduce risk of seizures

Some studies indicate GLP-1s can reduce the risk of seizures, though further investigation is needed.

Help with addiction

GLP-1s suppress hunger hormones, which can aid in managing food addiction. Some researchers propose they could be used to address other addictions, like alcohol or opioids.

Help with obstructive sleep apnoea

Even minor weight loss can significantly benefit those with sleep apnoea, according to Braund.

She explains that sleep apnoea results in waking up feeling more tired than before going to bed.

Benefits for PCOS

GLP-1s may benefit individuals with PCOS (polycystic ovarian syndrome) by reducing insulin resistance and regulating hormones and ovulation.

Braund suggests that weight loss from GLP-1s could help the body better regulate these processes.

Similarly, they may improve fertility, as obesity can negatively affect fertility in both men and women. Rapid weight loss can enhance fertility. However, GLP-1s can interfere with the effectiveness of contraceptive pills by slowing absorption.

The safety of GLP-1s during pregnancy is currently unknown.

Potential Negative Side Effects of GLP-1s

Nausea, vomiting, diarrhoea, indigestion, constipation

GLP-1s commonly trigger gastrointestinal issues because they slow stomach emptying and affect the brain region responsible for triggering vomiting.

Braund notes that most of these symptoms are mild and resolve quickly. Adjusting the dosage, starting with a lower dose, can help individuals adapt.

Bone fractures and muscle loss

Some research suggests GLP-1s might increase the risk of bone fractures due to reduced bone mineral density from weight loss, while other studies found no such risk.

Research from Mass General Brigham indicates that any form of weight loss, not just GLP-1 use, can lead to muscle loss.

Dr. Caroline Apovian, one of the researchers, explains that weight loss reduces caloric intake, including proteins, carbohydrates, and fats. Since the brain requires glucose and fat cannot be directly converted to glucose, muscle loss is often unavoidable when caloric intake is reduced.

The research found that combining a high-protein diet with regular exercise while using GLP-1s offers the greatest benefit in preserving bone and muscle mass compared to either approach alone.

An individual needs between 0.8g and 2.2g of protein per kg of body weight daily.

Headaches and dizziness

These are common when starting GLP-1s as the body adapts to the medication and typically diminish over time.

Mild tachycardia (increased heart rate)

This is another common and usually harmless side effect. Staying active and limiting alcohol and caffeine intake can help. Monitor closely if you have an existing heart condition and contact your doctor if you experience palpitations or chest pain.

Upper respiratory tract infection

This is listed as a common side effect for some GLP-1s in New Zealand. While a direct causal link hasn't been established, these infections can be linked to the symptoms.

GLP-1s can cause acid reflux, which irritates the throat. They also stimulate the vagus nerve, which influences the immune system, digestion, and heart rate.

This side effect typically decreases over time.

Hair loss

Hair loss is listed as a common side effect of Wegovy. Braund notes that it's difficult to determine whether hair loss is caused by the drug or simply occurs concurrently.

Medical assessors consider the timing of the effect relative to when the drug was taken when evaluating reported side effects.

Some individuals may experience skin reactions at the injection site, regardless of whether they're on a daily or weekly dose.

Braund suggests rotating injection sites, even though the injections are not painful. An oral version, which would eliminate this risk, may become available in New Zealand in the future.

Hypoglycaemia

Low blood sugar is a common side effect in individuals with type 2 diabetes who are taking GLP-1s.

Gastroparesis/stomach paralysis or delayed gastric emptying

GLP-1s slow down digestion, which, in rare cases, can become excessive and impair stomach muscle function, though this is rare.

Gallstones or gall bladder inflammation

GLP-1s also slow the gallbladder's emptying of bile, potentially increasing the risk of gallstones, another rare side effect.

Pancreatitis

A rare side effect of GLP-1s is pancreatitis, which involves inflammation of the pancreas, leading to severe upper abdominal pain, nausea, and vomiting.

Recent studies indicate the risk is minimal, but monitoring for these symptoms and consulting a doctor if concerns arise is important.

Potential increased risk of diabetic retinopathy, NAION

The American Academy of Ophthalmology reports that vision loss is a rare potential side effect of GLP-1s, though more research is needed.

Recent studies suggest GLP-1s may increase the risk of diabetic retinopathy and non-arteritic anterior ischemic optic neuropathy (NAION). Diabetic retinopathy is listed as a possible side effect on GLP-1 data sheets in New Zealand.

Braund emphasizes that this is an evolving area and the information available is subject to change.

If you experience unwanted side effects while taking GLP-1s, seek assistance from your prescriber or report them directly to Medsafe.

Braund explains that medical assessors will review reports to identify any areas of significant concern.

Ministry of Health clinical guidelines recommend combining weight-loss drugs with lifestyle changes.