Lariam (Mefloquine)

Lariam, known generically as mefloquine, is an antimalarial medicine used to prevent and treat malaria, particularly infections caused by Plasmodium falciparum and Plasmodium vivax. It interferes with the growth of malaria parasites in the red blood cells of infected people. Lariam is especially important in areas where malaria strains are resistant to other treatments, making it an important option for travellers and people living in endemic regions.

What Is Lariam

Lariam (mefloquine hydrochloride) is a medicine used against malaria. It is available as a tablet. Each tablet contains 250 mg of the active ingredient and is taken by mouth. This medicine slows the growth of the organisms causing infection in the bloodstream.

In warm-climate regions, malaria remains a serious public health threat. This disease is caused by a parasite transmitted to humans through the bites of infected mosquitoes. Malaria can be life-threatening, and symptoms usually appear 10 to 15 days after a mosquito bite, although this can vary.

The parasite mainly targets red blood cells, and the symptoms often resemble the flu. In severe cases, people may experience seizures or coma, which can ultimately lead to death. Jaundice, which causes yellowing of the skin, is also commonly linked with this infection. While malaria is nearly absent in most developed countries, it remains common in Africa, where it causes many deaths. The disease is also found in some parts of South America and Asia.

The parasites that cause malaria belong to the Plasmodium genus, with five species able to infect humans. Transmission occurs through the saliva of female mosquitoes, which are the ones that bite for blood. Once inside the body, the parasites multiply in the liver. P. falciparum is the most dangerous of the five species, while P. vivax, P. ovale, and P. malariae are less aggressive. A fifth species, P. knowlesi, rarely infects humans. Health authorities have introduced various prevention strategies to reduce malaria in endemic regions and have highlighted the need for effective treatments. This article discusses one of the most effective medicines used to treat malaria.

Ingredients

Lariam's main active ingredient is mefloquine hydrochloride. This drug dissolves only slightly in water. It is a white crystal with a molecular weight of 414.78 g/mol. It is chemically similar to quinine.

Each tablet also contains several inactive ingredients in addition to the 250 mg of active substance. For the full list of ingredients, read the medicine packaging.

Mefloquine is classified as a 4-quinolinemethanol derivative and acts as a blood schizonticide, targeting the erythrocytic stages of the malaria parasite. Mefloquine is taken by mouth, usually as 250 mg tablets. It has a long elimination half-life of about 2 to 4 weeks, which allows for convenient weekly dosing when used for prevention.

Despite its effectiveness, mefloquine is linked with various side effects, including neuropsychiatric reactions, which can continue even after stopping the drug. Because of these possible effects, it is contraindicated in people with a history of psychiatric illness or seizures. Mefloquine's unique pharmacokinetic properties and mechanism of action make it an important option in malaria-endemic regions, especially where resistance to other antimalarials has developed.

Uses

Lariam is primarily used to prevent and treat malaria. It is effective against both Plasmodium falciparum and Plasmodium vivax, including strains resistant to chloroquine. Lariam may be taken once weekly to help prevent malaria, starting one week before entering a malaria-endemic area. It is also used in acute malaria, usually given as a single oral dose for treatment.

Treatment of Acute Malaria Infections

The most common malaria treatment uses a combination of two drugs. The first is usually artemisinin. The second may be lumefantrine or mefloquine (Lariam). Quinine and doxycycline may be used as an alternative to artemisinin. Other compounds may also be used as the second medicine.

When the first symptoms appear, you should see a doctor. A blood test must confirm the presence of the disease. Treatment should begin only after a positive result. This helps avoid drug resistance. For example, artemisinin is ineffective in some parts of Asia because of resistance.

Lariam is used to treat acute malaria infections caused by P. falciparum and P. vivax. It is most useful for mild to moderate infections. It works against mefloquine-susceptible parasite strains. Researchers have not documented its effect on P. ovale and P. malariae.

Doctors need to be particularly careful with patients infected with P. vivax. While Lariam stops the parasites from growing, it does not clear them from the liver. After treatment with Lariam, a second treatment with primaquine may be needed. Another similar compound may also be used. This helps clear parasites from the liver and reduce the risk of relapse.

Prevention of Malaria

As with other diseases, prevention is better than treatment. Some of the most effective ways to prevent malaria are:

• in areas where malaria is common, people should avoid mosquito bites; for example, by sleeping under mosquito nets;
• using mosquito repellents during daily activities;
• using insecticides to eliminate mosquitoes from homes and other premises;
• removing standing water to stop mosquitoes from breeding;
• introducing fish species that eat mosquito larvae into ponds and lakes;
• vaccination and immunisation campaigns.

The last point is useful for people travelling to areas where malaria is common. Some medicines are available for this purpose. Lariam offers some protection against infections caused by P. falciparum and P. vivax. It is effective against strains of P. falciparum that are resistant to chloroquine.

Children in some regions receive a combination of sulfadoxine and pyrimethamine for prevention. Women who are more than 3 months pregnant should receive the same combination. Only one malaria vaccine is available, and it reduces the risk of infection by 40%. However, pharmaceutical companies are still trying to find more effective treatments.

Dosage

In Australia, you should never deviate from the doctor's instructions for taking Lariam. Increasing or reducing the prescribed mefloquine dose can be counterproductive. Here are some general recommendations for using this medicine for prevention:

• Unless otherwise directed, take one dose a week. Choose a regular day each week for your dose, such as every Monday.
• You should start taking this medicine at least 1 week in advance for better prevention. This means taking it before you enter an area where malaria is common.
• Use the medicine as described above while you are in the risk area. Do not stop the weekly doses when you leave the risk area. You should keep taking them for at least one month.
• If you stop using Lariam, use a different prevention method.

As well as this medicine, you should also use the other prevention methods mentioned earlier in this article.

Adult Patients

The recommended dose is five Lariam tablets to treat the infection in adults. You must take them all as a total dose of 1250 mg. For best tolerance, take the dose after your main meal. Swallow it with water. If this treatment does not give a positive result within 2 or 3 days, the doctor should use a different drug. Likewise, a different medicine should be used for treatment if malaria develops while you are using this medicine for prevention.

For prevention, follow the recommendations listed above. Start taking Lariam 2-3 weeks in advance if you use other medicines. This helps the doctor check whether the medicines interact.

Pediatric Patients

Doctors should not prescribe Lariam to babies less than 6 months old. Only a doctor should prescribe it to treat malaria in such a case. Children weighing under 20 kg should not use this medicine for prevention.

The most convenient infant dose is 20-25 mg per kg of body weight. This is a single dose. However, to help avoid serious unwanted effects, the doctor may divide the dose. The child may take two doses separated by a 6-8-hour interval. As already described, the tablet can be crushed if needed. You can then mix it with water, milk or another drink to make it easier to give.

For malaria prevention, children must take a weekly dose. This is 5 mg per kg of body weight. As a rule of thumb, you can use the doses summarised in the following table:

If there is no improvement within 2-3 days of treatment, use a different drug. Likewise, if Lariam does not prevent malaria, choose a different medicine for treatment. Children are more likely to vomit after taking this product. If this happens, follow the advice given earlier in this article.

You should take these tablets after your main meal. Swallow the tablet with plenty of water (approximately 250 ml). If it is hard to swallow, you can crush it. Mix the resulting powder with a drink you like to make it easier to take.

Taking Lariam may cause vomiting. This may happen within half an hour of taking this medicine. In that case, you will need to take another dose. You should retake only half a dose if vomiting happens between half an hour and one hour later. If Lariam continues to cause vomiting, seek medical attention.

Geriatric Patients

There is no consensus about using Lariam in older adults (+65 years old). Some researchers did not find any difference compared with younger patients. However, some studies have reported cardiac abnormalities linked with this drug. Because of this, the doctor needs to assess carefully whether Lariam is suitable for an older patient.

What Is the Onset of Action for Lariam?

Lariam (mefloquine) typically begins to work within one week when used for malaria prevention, as it is recommended to start taking the medicine at least one week before entering a malaria-endemic area. For the treatment of malaria, Lariam can be effective within 24 hours after administration. However, symptoms may take longer to settle depending on the severity of the infection and the individual's response to the medicine. It is important to seek medical attention promptly if symptoms persist or get worse.

Important Safety Information

Long-term use of Lariam requires regular blood tests. Because of mefloquine toxicity, these tests are needed to make sure your liver remains in good condition. Long-term use of Lariam may also affect your vision. Consider having regular eye checks with an ophthalmologist.

People with a history of depression, anxiety disorders, seizures or other mental illnesses should avoid using Lariam for malaria prevention. Additionally, it is crucial in Australian clinical practice to inform healthcare providers about any existing medical conditions, such as epilepsy or liver problems, before starting treatment.

Pregnancy and Breastfeeding

Animal studies suggest that Lariam can affect embryo development. However, similar studies have not been carried out in pregnant women. There is no evidence that Lariam can affect human foetuses. In any case, there must be a strong reason to use Lariam during pregnancy. Women travelling to a risk area should avoid becoming pregnant. Ask your pharmacist about effective contraception.

Mefloquine is present in small amounts in breast milk. The drug can cause severe reactions in the baby. Because of this, the doctor must decide whether Lariam should be discontinued. The doctor must weigh the mother's benefit against the baby's risk.

Pediatric Use

Multiple clinical trials support the use of Lariam in children younger than 16 years old. In such cases, it is safe and effective at the recommended doses. Researchers have not documented its use in babies under 6 months of age. It is better to avoid using Lariam in such young infants.

Contraindications

You should avoid using Lariam if you have had mental illness before. These include anxiety, depression and schizophrenia. You should also avoid using this medicine if you have had seizures. In some life-threatening cases of malaria, the doctor may still prescribe Lariam. In that situation, the benefit of saving your life may outweigh the risk of Lariam-related psychosis.

Tell the doctor about any other medical conditions you have or have had. For example, let them know if you have heart or liver problems. The doctor also needs to know whether you have other conditions such as epilepsy or diabetes. Tell them if you are allergic to any medicines. Allergy to mefloquine, quinine or quinidine is especially important in this case.

Drug-Drug Interactions

Researchers have not studied drug interactions in detail. Hence, for your safety, inform the doctor about all other medicines you take, including Australian over-the-counter products. This should include medicines that do not need a prescription. You should also tell them about any vitamin supplements and herbal products you use.

The doctor will pay special attention to the following:

• medicines for heart disease and high or low blood pressure;
• medicines for depression and other mental health conditions;
• medicines used to control seizures;
• medicines for tuberculosis;
• live vaccines.

You should also tell them about any recreational drugs you use.

Side Effects

At the recommended doses, Lariam is safe in most cases. However, in some emergencies you may need to go to hospital straight away. For example, if you have an allergic reaction to the medicine. Symptoms of such a reaction include swelling of the face or other parts of the body. Trouble breathing and hives can also be signs of an allergic reaction.

Clinical

Most side effects are mild and may include dizziness, vomiting, diarrhoea and flu-like symptoms. These symptoms usually do not require special medical attention. It may be difficult to tell these effects apart from the symptoms of malaria.

Psychiatric or Nervous System Problems

Lariam may affect the nervous system. The patient may experience mental health problems and other unwanted effects. These are mefloquine's long-term side effects. These psychiatric problems can last a long time. Even if the patient stops taking the medicine, the problems may remain. In some extreme cases, they can last for years or become permanent.

Tell the doctor about your full medical history. With this information, the doctor will assess whether Lariam is appropriate for you. The doctor will try to keep the risk of these long-term side effects as low as possible. Stop using Lariam straight away if you experience any of these issues:

• headache;
• tinnitus;
• dizziness or difficulty keeping your balance;
• lack of coordination;
• changes in mood or thinking, such as depression or suicidal thoughts.

Seek medical attention if you experience any of the above effects.

Postmarketing

Most side effects in this category include vertigo, dizziness and loss of balance. Other reported problems are:

• sleep disorders (nightmares, insomnia);
• cardiovascular disorders (high or low blood pressure, arrhythmias);
• skin disorders (rash, itching);
• muscular disorders (weakness, cramps);
• respiratory disorders.

Other effects have also been reported. Not all of them are listed above. People have reported visual problems, fatigue, malaise and other symptoms. This is in addition to the psychiatric and nervous system problems mentioned earlier in this article.

Overdose

You may have symptoms of poisoning. In that case, seek emergency medical attention. In Australia, for example, you can call 000.

Most commonly, you may have breathing problems after an overdose. You may pass out. Do not waste time and seek emergency medical attention in Australia.

Missed Dose

Missing a dose should not be a major problem in treatment cases. You generally take a single dose of Lariam, so take the dose as soon as you realise you missed it.

If you miss a dose of Lariam during prevention, take it as soon as you can. Then take the next dose as scheduled. However, if you miss the dose within a week before entering a risk area, contact the doctor. You will need a different prevention method.

Comparison of Lariam with Other Antimalarials

Here's a comparison of Lariam with other common antimalarials:

Lariam is often chosen because its weekly dosing schedule may be more convenient for some travellers. However, it is linked with more severe side effects than alternatives such as Malarone and doxycycline. Malarone offers rapid protection and milder side effects but at a higher cost. Doxycycline is effective and affordable but needs to be taken daily, which some people may find difficult. Chloroquine is no longer recommended in many malaria-endemic areas because of resistance.

Lariam and Hydroxychloroquine: Key Differences and Uses

Lariam (mefloquine) and hydroxychloroquine are both medicines used to treat and prevent malaria, but they differ significantly in how they work, when they are used and the side effects they may cause.

Lariam (Mefloquine)

Uses:

• Lariam is indicated for the treatment of mild to moderate acute malaria caused by mefloquine-susceptible strains of P. falciparum and P. vivax. It is particularly useful against chloroquine-resistant strains.
• It is also used for prophylaxis against malaria in travellers to areas where chloroquine-resistant strains are prevalent.

Mechanism of Action:
Mefloquine acts by interfering with the parasite's ability to digest haemoglobin, leading to its death. It is effective against both chloroquine-sensitive and resistant strains of malaria.

Side Effects:
Common side effects include dizziness, nausea, vomiting, and sleep disturbances. Serious side effects can include neuropsychiatric symptoms such as anxiety or depression, which may occur due to its effects on the central nervous system.

Hydroxychloroquine

Uses:

• Hydroxychloroquine is mainly used to treat uncomplicated malaria caused by certain strains of Plasmodium (for example, P. falciparum, P. malariae, P. ovale, and P. vivax) in areas where chloroquine resistance has not been reported.
• It is also widely prescribed for autoimmune conditions such as rheumatoid arthritis and systemic lupus erythematosus, where it acts as a disease-modifying antirheumatic drug (DMARD).
• Hydroxychloroquine may also be used for conditions such as discoid lupus erythematosus and porphyria cutanea tarda.

Mechanism of Action:
Hydroxychloroquine works by modulating the immune response and increasing lysosomal pH, which helps inhibit the growth of malaria parasites. It also has anti-inflammatory effects that are helpful in autoimmune conditions.

Side Effects:
Common side effects include nausea, vomiting, headache, and blurred vision. Serious side effects can include retinopathy, skin reactions (for example, Stevens-Johnson syndrome), blood disorders, and liver damage.

Comparison Table

Storage

Store your Lariam in a dry place. The temperature can range from 15°C to 30°C, ideally around 25°C. Keep the tablets out of reach of children.

Brand names for mefloquine in different countries