Lariam (Mefloquine Hydrochloride) tablets

Lariam, known generically as mefloquine, is an antimalarial medication used to prevent and treat malaria, particularly those caused by Plasmodium falciparum and Plasmodium vivax. It disrupts the growth of malaria parasites in the red blood cells of infected individuals. Lariam is especially important in areas where malaria strains are resistant to other treatments, making it a critical option for travelers and residents in endemic regions.

What Is Lariam

Lariam (mefloquine hydrochloride) is a medication against malaria. It is commercially available as a tablet. These tablets contain 250mg of the active substance each. They are for oral administration. This medicine hampers the growth of the invading microorganisms in the bloodstream.

In regions with warm climates, malaria poses a serious public health threat. This disease is caused by a parasite that is transmitted to humans through the bites of infected mosquitoes. Malaria can be life-threatening, with symptoms typically emerging 10 to 15 days after a mosquito bite, although this incubation period can vary.

The parasite primarily targets red blood cells; the symptoms often resemble the flu. In severe cases, individuals may experience seizures or coma, which can ultimately lead to death. Jaundice, characterized by yellowing of the skin, is also commonly associated with this infection. While malaria is nearly absent in most developed countries, it remains prevalent in Africa, where it accounts for numerous fatalities. The disease is also found in some regions of South America and Asia.

The parasites responsible for malaria belong to the Plasmodium genus, with five species capable of infecting humans. The transmission occurs through the saliva of female mosquitoes, the only ones that bite for blood. Once inside the body, the parasites reproduce in the liver.  P. falciparum is the most lethal among 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 implemented various prevention strategies to combat malaria in endemic regions and emphasized the need for effective treatments. This article will discuss one of the most effective medications for treating malaria.

Ingredients

Larian’s main active substance is mefloquine hydrochloride. This drug dissolves slightly in water. It is a white crystal with a molecular weight of 414.78 g/mol. It is chemically analogous to quinine.

Each tablet contains several inactive components besides the 250mg of the active substance. For the entire list of ingredients, you may read the medicine package.

Mefloquine is classified as a 4-quinolinemethanol derivative and works as a blood schizonticide, targeting the erythrocytic stages of the malaria parasite. Mefloquine is administered orally, typically 250 mg tablets. It exhibits a long elimination half-life of approximately 2 to 4 weeks, allowing for convenient weekly dosing in prophylactic use.

Despite its effectiveness, mefloquine is associated with various side effects, including neuropsychiatric reactions, which can persist even after discontinuation of the drug. Due to these potential adverse effects, it is contraindicated in individuals with a history of psychiatric disorders or seizures. Mefloquine’s unique pharmacokinetic properties and mechanism of action make it a crucial 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. While Lariam can be taken as a weekly prophylactic measure starting one week before entering a malaria-endemic area, it is also used in acute malaria cases, typically administered as a single oral dose for treatment.

Treatment of Acute Malaria Infections

The most common treatment against malaria uses a combination of two drugs. The first one is generally artemisinin. The second one can be lumefantrine or mefloquine (Lariam). It is possible to use quinine and doxycycline as a substitute for artemisinin. Likewise, using other chemical compounds as the second medication is possible.

When the first symptoms appear, a visit to the doctor is a must. A blood test must confirm the presence of the disease. The treatment should begin only after positive confirmation. This will help avoid the problem of drug resistance. For example, artemisinin is ineffective in some parts of Asia due to resistance.

Lariam effectively combats acute malaria infections caused by P. falciparum and P. vivax. It is most effective against mild to moderate infections. It works well with susceptible and resistant parasite strains to mefloquine. Researchers have not documented its effect on the P. ovale and P. malariae species.

Doctors must be watchful with patients infected with P. vivax. While Lariam inhibits the growth of the parasites, it does not eliminate them from the liver. After the treatment with Lariam, a second treatment with primaquine is convenient. It is possible to use another similar chemical compound. This will eliminate the parasites from the liver and prevent a relapse.

Prevention of Malaria

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

• in areas with Malaria prevalence, people must keep mosquitoes away; for example, people should use mosquito nets when sleeping;
• the use of mosquito repellents when doing daily activities;
• the use of insecticides to eliminate mosquitoes from houses and other premises;
• removal of standing water to avoid the reproduction of mosquitoes;
• introduction of some species of fish that eat mosquito larvae in ponds and lakes;
• campaigns for vaccinations and immunizations.

The last point is helpful for people traveling to areas where malaria is common. Some drugs are available for this purpose. Lariam offers some protection against infections by P. falciparum and P. vivax. It is effective against strains of P. falciparum that develop resistance to chloroquine.

Children in some regions get a combination of sulfadoxine with pyrimethamine as prevention. Women with more than 3 months of pregnancy should get the same combination. Only one malaria vaccine is available, which lowers the risk of infection by 40%. However, pharmaceutical companies are trying to find more effective treatments.

Dosage

You should never deviate from the doctor’s indications to take Lariam. Increasing or reducing the prescribed mefloquine dose can be counterproductive. Here are some general recommendations for using this medicine for prevention:

• Unless otherwise indicated, you should take one dose a week. Choose a day for your dose each week (every Monday, for example).
• You should start taking this medicine at least 1 week in advance for better prevention. This means taking the medication before you enter an area with Malaria prevalence.
• Use the medicine as described above in the risk area. Do not discontinue the weekly doses when you leave the risk area. You should continue taking them for at least one month.
• If you discontinue using Lariam, use a different prevention method.

Besides this medicine, other prevention methods mentioned earlier in this article should be used.

Adult Patients

The recommended dose is five Lariam pills to combat the infection in adults. You must take them all as a dose of 1250 mg. For your well-being, eat your main meal first. Use water to swallow the dose. If this treatment does not yield a positive outcome within 2 or 3 days, the doctor should use a different drug. Likewise, a different medication should treat the infection if you use this medicine for prevention.

For prevention, follow the recommendations listed above. Start taking Lariam 2-3 weeks in advance if you use other medications. This will help the doctor determine whether all the drugs have an interaction.

Pediatric Patients

Doctors should not prescribe Larian to babies less than 6 months old. Only a doctor could prescribe it to treat malaria in such a case. Children under 20 kg of weight should not use this medicine as a preventive measure.

The most convenient infant dose is 20-25 mg per kg of body weight. This is a single dose. But, to avoid serious unwanted effects, the doctor may divide the dose. The child could take two doses separated by a 6-8-hour interval. As already described, it is possible to crush the tablet if necessary. Then, you can mix it into water, milk, or any other drink.

As a malaria prevention method, 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 summarized in the following table:

Weight of the Infant	Recommended Weekly Dose
> 45 kg	1 entire tablet
30-45 kg	¾ of a tablet
20-30 kg	½ of a tablet
< 20 kg	Do not use

If there are no positive results for treatment within 2-3 days, use a different drug. Likewise, if Lariam could not prevent malaria, choose a different medication for treatment. Children are more susceptible to suffering from vomiting after taking this product. If this happens, follow the recommendations given earlier in this article.

You should take these tablets after eating your main meal. Drink a tablet with abundant water (approximately 250 ml). If it is difficult to swallow it, you can crush it. Mix the resulting powder with a drink you like. This will ease the administration.

Taking Lariam may cause vomiting. It may happen within half an hour after the administration of this medicine. In such a case, you will need to take another dose. You should retake only half a dose if the vomiting happens between half an hour and one hour. If Lariam continues causing vomit, seek medical attention.

Geriatric Patients

There is no consensus about using Lariam in senior adults (+65 years old). Some researchers did not detect any difference in the treatment in younger patients. However, some studies have reported cardiac abnormalities as a result of using this drug. Hence, the doctor has to carefully assess the suitability of Lariam for a senior 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 medication 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 resolve depending on the severity of the infection and the individual’s response to the medication. It is important to note that medical attention should be sought promptly if symptoms persist or worsen.

Important Safety Information

The long-term use of Lariam requires regular blood tests. Because of mefloquine toxicity, these tests are necessary to ensure that your liver is in good condition. Your vision may suffer, too, due to long-term use of Lariam. Consider visiting the ophthalmologist regularly.

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

Pregnancy and Breastfeeding

Experiments with animals indicate that Lariam can affect the development of an embryo. However, similar studies have not been conducted with pregnant women. There is no evidence that Lariam can affect human fetuses. In any case, there must be a strong justification to use Lariam on a pregnant woman. Women traveling to a risk zone should avoid becoming pregnant. Ask your pharmacist for effective birth control methods.

Mefloquine is present in small concentrations in breast milk. The drug can cause severe reactions to the baby. Hence, the doctor must determine whether to discontinue the use of Lariam. The doctor must assess the mother’s benefit versus the baby’s danger.

Pediatric Use

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

Contraindications

You should refrain from using Lariam if you have had mental illness before. These include anxiety, depression, and schizophrenia. Also, refrain from using this medicine if you have had seizures. For some life-threatening Malaria cases, the doctor may still prescribe Lariam. In this case, the benefit of saving your life will outweigh the danger of Lariam’s psychosis.

Inform the doctor about other medical conditions that you suffer or have suffered. For instance, tell them whether you have problems with the heart or liver. The doctor must know whether you have other conditions like epilepsy or diabetes. Inform if you have an allergy to some specific medicines. Allergy to mefloquine, quinine, or quinidine is of special interest in this case.

Drug-Drug Interactions

Researchers have not studied in detail the drug-drug interactions. Hence, inform the doctor about all other medicines you take for your safety. This should include medicines that need no prescription. You should also be informed about vitamin supplements and herbal products you use.

The doctor will give special attention to the following:

• medicines for cardiac diseases and hypertension/hypotension;
• medicines against depression and other mental disorders;
• medicines to control seizures;
• medicines against tuberculosis;
• vaccines with live agents.

Also, you should tell about any type of recreational drug that you use.

Side Effects

With the recommended doses, Lariam is safe in most cases. But you may go immediately to a hospital in some emergency cases. For example, if you have an allergic reaction to the medication. Symptoms of such a reaction include swelling of your face and other parts. Problems with breath and hives are also indicators of an allergic reaction.

Clinical

Most side effects are mild and may include dizziness, vomiting, diarrhea, and symptoms like the flu. These symptoms do not require special medical attention. It will be difficult to distinguish these effects from the symptoms of malaria.

Psychiatric or Nerve System Problems

The use of Lariam may affect the nervous system. The patient may experience some mental problems and other unwanted effects. These are mefloquine’s long-term side effects. These psychiatric problems can remain for 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 stay permanently.

Inform the doctor about your entire medical history. With this information, the doctor will assess the convenience of taking Lariam. The doctor will ensure a low risk of these long-term Lariam side effects. Discontinue the use of Lariam straight away if you experience some of these issues:

• headache;
• tinnitus;
• dizziness or difficulty in keeping balance;
• lack of motion coordination;
• abnormal states of mind, such as depression or suicidal thoughts.

Seek medical attention after experiencing 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, pruritus);
• muscular disorders (weakness, cramps);
• respiratory disorders.

There are other effects reported. Not all are in the list above. People have reported visual problems, fatigue, malaise, and other ailments. One has to add the psychiatric and nerve problems mentioned earlier in this article.

Overdose

You may have some poisoning symptoms. In such a case, seek emergency medical attention. In the United States, for example, you can dial 911.

Most commonly, you can have problems breathing after overdosing. You may pass out. Do not waste time and seek emergency medical attention.

Missed Dose

Missing a dose should not represent a big problem in therapeutic cases. You generally take a single dose of Lariam. So, you take the dose when you notice that you missed it.

If you miss a dose of Lariam during a prevention treatment, take it at your earliest convenience. Then, take the next dose as scheduled. But if you miss the dose within a week before you enter a risk zone, 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: