Minoxidil is a medication primarily known for its use in promoting hair growth. Originally developed as an oral medication for high blood pressure (under the brand name Loniten), it was observed that patients taking the medication often experienced increased hair growth as a side effect. This led to the development of a topical formulation of minoxidil specifically for hair growth.

Minoxidil (Loniten) is a drug that causes vasodilation. It is rarely used in the management of hypertension in patients resistant to a diuretic and two other antihypertensive medications.

Minoxidil (Loniten) Uses:

• Hypertension:
  • It is suggested for the treatment of symptomatic hypertension or that which is linked to target organ damage, resistance to a diuretic, and the use of two additional antihypertensives.
  • Not recommended in milder hypertension because the benefit-risk ratio is not defined.

Note: It is not suggested to be used as an initial treatment for high blood pressure.

Minoxidil Dose in Adults:

Minoxidil (Loniten) Dose as an alternative agent in the treatment of Hypertension:

• When starting, take 5 mg once a day.
• The dose can be increased slowly, and if needed quickly, it can be taken up to 4 times a day.
• But the maximum amount you can take in a day is 100 mg.

Remember:

• If you're taking other blood pressure medicines, the amount of minoxidil might need to change.
• If laying down, your blood pressure drops a little (less than 30 mm Hg), take it once a day. If it drops a lot (more than 30 mm Hg), split the dose into two equal parts.

Minoxidil Dose in Children:

Minoxidil (Loniten) Dose in the therapy of extremely high blood pressure; resistant to multiple drugs:

Children under 12 years old:

• Start with: 0.2 mg per kilogram of their weight once a day. Don't give more than 5 mg at first.
• Increase the dose: You can raise it by 50% to 100% every 3 days. If needed, spread the dose over 1 to 3 times daily.
• Usual amount: Most children take between 0.25 to 1 mg per kilogram daily, split into 1 to 3 doses.
• Maximum in a day: 50 mg.
• If blood pressure needs to be lowered quickly, you can adjust the dose every 6 hours, but watch the child closely.

Children 12 years old and older, and teenagers:

• Start with: 5 mg once a day.
• Increase the dose: Double the dose every 3 days (like 10 mg, then 20 mg, then 40 mg). If needed, spread the dose over 1 to 3 times daily.
• Usual amount: Most take between 10 to 40 mg daily, split into 1 to 3 doses.
• Maximum in a day: 100 mg.
• If blood pressure needs to be lowered quickly, adjust the dose every 6 hours but watch them closely.

Pregnancy Risk Factor C

• In some studies involving animals, adverse events were noted.
• One notable effect is neonatal hypertrichosis, which means excessive hair growth in newborns.
• This has been reported in cases where minoxidil was used during pregnancy.
• It's important to be aware of these potential risks and consult with a healthcare provider when considering the use of minoxidil, especially during pregnancy or if you are planning to become pregnant.

Use during breastfeeding:

• When a woman took 10 mg/day of minoxidil by mouth, it was found in her breast milk in one study.
• This means that the drug can be passed to the infant through breastfeeding.
• Because of the possible side effects on the baby, the company that makes minoxidil recommends that breastfeeding mothers should not use the drug.

Dose in Kidney Disease:

• The company that makes the drug doesn't give exact dosing instructions for patients with kidney problems or those on dialysis.
• However, they do mention that these patients might need a lower dose.

Dose in Liver disease:

• The company that makes the drug doesn't give specific instructions on dose changes for patients with liver problems.
• But they advise using the drug carefully.
• One study (Adams 1998) found that in patients with mild liver cirrhosis, the amount of minoxidil in the body was 50% higher, and it took longer for the body to clear it out.

Side effects of Minoxidil (Loniten):

• Dermatologic:
  • Toxic Epidermal Necrolysis
  • Skin Rash
  • Hypertrichosis
  • Bullous Rash
  • Stevens-Johnson Syndrome
• Cardiovascular:
  • ECG Changes
  • Edema
  • Pericardial Effusion
  • Angina Pectoris
  • Cardiac Failure
  • Pericarditis
  • Tachycardia
• Endocrine & Metabolic:
  • Sodium Retention
  • Water Retention
  • Weight Gain
• Gastrointestinal:
  • Nausea
  • Vomiting
• Hematologic & Oncologic:
  • Hemoglobin
  • Leukopenia
  • Decreased Hematocrit
  • Decreased Red Blood Cells
  • Thrombocytopenia
• Respiratory:
  • Pulmonary Edema
• Hepatic:
  • Ascites
  • Increased Serum Alkaline Phosphatase
• Renal:
  • Increased Blood Urea Nitrogen
  • Increased Serum Creatinine

Contraindications to Minoxidil (Loniten):

Minoxidil shouldn't be used by people who:

• Are allergic to minoxidil or any ingredients in the drug.
• Have pheochromocytoma, a type of tumor.

In Canada, there are extra warnings:

• Don't use minoxidil if you have high blood pressure in the lungs linked to a narrow mitral valve in the heart.
• Don't use it if you have serious liver problems.

Warnings and precautions

Fluid retention:

• Minoxidil can make your body hold onto more salt and water, which can cause swelling.
• To avoid this, it's usually given with a water pill, like furosemide.
• Be very careful using minoxidil if you have heart problems, as the swelling can be dangerous.

Pericardial effusion/tamponade [US Boxed Warn]

• Minoxidil has a strong warning because it can cause heart issues like pericarditis (inflammation of the heart's lining) and pericardial effusion (fluid around the heart).
• This fluid can build up and squeeze the heart (called tamponade).
• People with kidney problems not on dialysis might be at an even higher risk.
• If someone has heart failure, they should be extra careful and monitored closely.

Control blood pressure quickly

• Quickly lowering blood pressure in people with very high blood pressure can cause serious problems.
• They might faint, have a stroke, a heart attack, or even lose vision or hearing.
• People with blood flow issues or a condition called cryoglobulinemia can face additional risks where certain organs don't get enough blood.

Sinus tachycardia [US Boxed Warning]

• Minoxidil has a strong warning because it can cause a fast heart rate, which might need more oxygen and make chest pain (angina) worse.
• Taking it with a certain kind of heart medicine called a beta-blocker can help reduce this effect.
• People with heart disease that's caused by reduced blood flow should be extra careful with minoxidil.

Acute myocardial injury (MI)

• After a recent heart attack, don't use minoxidil for a month because it can make the heart need more oxygen by causing a fast heart rate.
• If considering its use later, be very careful and make sure the person is also taking a heart medicine called a beta-blocker.

Heart failure:

• Minoxidil can make heart problems worse.
• Studies show that people on minoxidil, compared to those not on it, had more heart-related issues, like needing water pills, chest pain, irregular heartbeats, worse heart failure, and even death.
• The American Heart Association has also said that minoxidil can make existing heart problems more severe.

Renal impairment

• If someone has kidney problems, be careful with minoxidil.
• People with severe kidney issues or those on dialysis might need a lower dose.
• Keep a close eye on these patients to make sure their kidney condition doesn't get worse.

Minoxidil (topical): Drug Interaction

Monitoring parameters:

Blood Pressure:

• Check both when standing and sitting/lying down.

Heart Issues:

• Look for signs of fluid around the heart (pericardial effusion).

Fluids and Weight:

• Keep track of body fluids, salts, and body weight.

Regular Tests:

• If any tests (like kidney tests, ECG, heart ultrasound, or chest x-ray) were not normal when starting, redo them every 1-3 months at first. Once things are stable, do them every 6-12 months.

2017 Blood Pressure Guidelines (ACC/AHA [Whelton 2017]):

• High Blood Pressure with Heart Disease or High Risk: Aim for a blood pressure less than 130/80 mm Hg.
• High Blood Pressure without High Risk: Keeping blood pressure under 130/80 mm Hg might be a good idea.

Mechanism of action of Minoxidil (Loniten):

• Minoxidil works by making small blood vessels relax and widen, mainly affecting arteries and not so much veins.
• This might involve a substance called cyclic AMP.
• The way it helps hair grow is by improving blood flow to the skin and energizing hair follicles that aren't active.

How Minoxidil Works:

• Onset: It starts lowering blood pressure in about 30 minutes.

Strongest Effect:

• Peak: The most significant drop in blood pressure happens around 2 to 3 hours after taking it.

How Long It Lasts:

• Duration: Its effects can last for up to 2 to 5 days.

What Happens Inside the Body:

• Protein Binding: Minoxidil doesn't stick to proteins in the body.
• Metabolism: About 90% of it gets changed in the body, mainly through a process called glucuronidation.

How Much Gets in the Blood:

• Bioavailability: Around 90% of the minoxidil you take actually gets into your bloodstream.

How Long It Stays in the Body:

• Half-life: The time it takes for half of the minoxidil to leave your body is about 3.5 to 4.2 hours.

How It Leaves the Body:

• Excretion: Most of it (about 88%) leaves your body through urine, and a small amount (12%) stays unchanged.

International Brand Names of Minoxidil:

• Loniten
• Guayaten
• Loniten
• Lonnoten
• Lonolox
• Lonoten
• Manoxidil
• Midil
• Noxidil
• Noxidil Forte

Minoxidil Brands Names in Pakistan:

Systemic minoxidil is not available in Pakistan. The common formulation is the topical solution and sprays used for hair growth.