Phendimetrazine is a sympathomimetic amine, which means it's a stimulant that affects the central nervous system. It is used as a short-term adjunct in the management of obesity, along with dietary and lifestyle modifications. It's typically prescribed when other weight loss efforts have failed. Phendimetrazine works by decreasing appetite, increasing metabolism, and affecting certain areas of the brain that control hunger.

Phendimetrazine (Bontril) is an anorectic drug similar to amphetamines. It suppresses appetite and increases the metabolic rate. It is used in the management of exogenous obesity as an adjunct to diet and exercise.

Phendimetrazine Uses:

• Obesity:
  • It is used in the management of obesity as a short-term treatment in adjunct to a low caloric diet and exercise.

Phendimetrazine (Bontril) Dose in Adults

Phendimetrazine (Bontril) Dose in the short-term treatment of Obesity: Oral: 

Phendimetrazine to help with weight loss for a short time, there are two ways to take it by mouth:

• Extended-release tablets:
  • You take 105 milligrams just once every day, about 30 to 60 minutes before eating breakfast in the morning.
• Immediate-release tablets:
  • You take 35 milligrams either 2 or 3 times a day, depending on what your doctor recommends.
  • Take it about an hour before meals.
  • Sometimes, you might only need half a tablet (17.5 milligrams) per dose.
  • But don't take more than 70 milligrams three times a day.

Phendimetrazine (Bontril) Dose in Children:

Refer to adults dosing.

Pregnancy Risk Factor X/C

• The risk of using Phendimetrazine during pregnancy is uncertain (Risk Factor X/C).
• Studies on pregnant animals haven't been done, but some manufacturers advise against using it during pregnancy because it might not benefit the mother and could potentially harm the baby.
• It's important to note that being overweight during pregnancy can increase the chances of problems for both the mother and the baby.
• However, medications like Phendimetrazine aren't recommended for weight loss during pregnancy or when planning to conceive, according to the American College of Obstetricians and Gynecologists.

Use during breastfeeding:

• It's not clear if Phendimetrazine passes into breast milk, but similar drugs called amphetamines have been found in breast milk before.
• Because there's a chance of harmful effects on the baby who is breastfeeding, it's important to think about whether to stop breastfeeding or stop taking the medication, depending on how important the drug is for the mother.
• Some manufacturers advise against using Phendimetrazine while breastfeeding.

Dose in Kidney Disease:

• The manufacturer's instructions don't mention any specific changes in dosage for people with kidney problems because this hasn't been studied.
• However, since Phendimetrazine is eliminated from the body through the kidneys, it's important to be cautious when using it if you have kidney issues.

Dose in Liver Disease:

• The manufacturer's instructions don't include any specific changes in dosage for individuals with liver problems.
• However, if you have liver issues, it's important to discuss this with your doctor before taking Phendimetrazine.

Side effects of Phendimetrazine (Bontril):

• Cardiovascular:
  • Flushing
  • Hypertension
  • Ischemic Events
  • Palpitations
  • Tachycardia
  • Valvular Disease (Regurgitant)
• Central Nervous System:
  • Agitation
  • Dizziness
  • Headache
  • Insomnia
  • Overstimulation
  • Psychosis
  • Restlessness
• Endocrine & Metabolic:
  • Changes In Libido
• Gastrointestinal:
  • Constipation
  • Diarrhea
  • Nausea
  • Stomach Pain
  • Xerostomia
• Genitourinary:
  • Dysuria
  • Urinary Frequency
• Neuromuscular & Skeletal:
  • Tremor
• Ocular:
  • Blurred Vision
  • Mydriasis
• Respiratory:
  • Primary Pulmonary Hypertension
• Miscellaneous:
  • Diaphoresis
  • Tachyphylaxis

Contraindications to Phendimetrazine (Bontril):

Phendimetrazine is not recommended for individuals who have a hypersensitivity or idiosyncrasy to phendimetrazine, other similar stimulant medications, or any of its components. It should also be avoided in people with conditions like glaucoma, severe nervousness, history of drug abuse, or hyperthyroidism. Taking Phendimetrazine along with other weight loss medications or CNS stimulants is not advised. Additionally, it should not be taken during or within 14 days following therapy with monoamine oxidase inhibitors (MAOIs).

• Extended-release Phendimetrazine is further contraindicated in individuals with a history of cardiovascular disease, pregnancy, or breastfeeding.

• Immediate-release Phendimetrazine is not recommended for those with advanced arteriosclerosis, symptomatic cardiovascular disease, or moderate to severe hypertension. These contraindications aim to prevent potential adverse effects and complications.

Warnings and precautions

CNS depression:

• Phendimetrazine may lead to CNS depression, which can affect physical and mental abilities.
• Patients should be careful when performing tasks requiring alertness like driving or operating machinery.

Heart failure:

• According to the American Heart Association, Phendimetrazine has been linked to potential myocardial toxicity, which can seriously affect the heart.

Hypertension in the lungs:

• Although rare, pulmonary hypertension may occur and can be fatal.
• Prolonged use of this medication for more than three months raises the risk.
• Seek medical attention if symptoms like difficulty breathing or chest pain occur.

Heart disease of the valvular kind:

• Long-term use or high doses of Phendimetrazine, especially when combined with other weight loss drugs, may contribute to valvular heart disease.
• Avoid use in individuals with known heart murmurs or valvular issues.

Diabetes:

• Caution is advised in patients with diabetes as Phendimetrazine may alter the requirements for diabetes medications due to dietary changes and appetite suppression.

Hypertension:

• Patients with hypertension or other heart conditions should use Phendimetrazine cautiously as it can increase blood pressure and heart rate.

Renal impairment

• Use caution in patients with kidney problems.

Seizure disorders:

• Individuals with a history of seizures should be cautious when using Phendimetrazine.

Tourette syndrome:

• Patients with Tourette syndrome should use Phendimetrazine cautiously as stimulants might worsen tic symptoms.

Phendimetrazine: Drug Interaction

Monitoring Parameters:

Baseline Cardiac Evaluation:

• Before starting Phendimetrazine, patients should undergo a cardiac evaluation to assess for preexisting conditions like valvular heart disease or pulmonary hypertension.

Echocardiogram During Therapy:

• Regular echocardiograms should be performed during Phendimetrazine therapy to monitor cardiac function and detect any potential complications.

Monitoring Weight and Waist Circumference:

• Regularly monitor weight and waist circumference to track progress and ensure safe use of Phendimetrazine.

Blood Pressure Monitoring:

• Monitor blood pressure regularly, especially in patients with hypertension or cardiovascular conditions, to detect any changes or exacerbation of existing conditions.

How to administer Phendimetrazine (Bontril)?

Extended-Release:

• Take the extended-release formulation of Phendimetrazine 30 to 60 minutes before your morning meal.

Immediate-Release:

• Take the immediate-release formulation of Phendimetrazine 1 hour before your meals.

Mechanism of action of Phendimetrazine (Bontril):

• Phendimetrazine is a type of drug called a sympathomimetic amine, which works in a way similar to amphetamines.
• It seems to reduce appetite by affecting the central nervous system (CNS).
• Specifically, it stimulates a part of the brain called the hypothalamus to release a chemical called norepinephrine, which helps control appetite.
• This action in the brain is what helps people feel less hungry when they take Phendimetrazine.

Metabolism:

• Phendimetrazine undergoes metabolism in the body, forming two metabolites: phenmetrazine and phendimetrazine-N-oxide.

Half-life elimination:

• The half-life of Phendimetrazine, which is the time it takes for half of the drug to be eliminated from the body, is approximately 3.7 hours.

Excretion:

• After metabolism, Phendimetrazine and its metabolites are primarily excreted through urine.

International Brand Names of Phendimetrazine:

• Bontril PDM
• Anoran
• Antapentan
• Atrajine
• Fendy 35
• Furing
• Obesan-X
• Pendimen
• Phendirazine
• Plegine
• Prelu-2

Phendimetrazine Brand Names in Pakistan:

No Brands Available in Pakistan.