Saquinavir Mesylate: Uses, Dosage, Precautions, Side Effects, and Pharmacological Aspects

What Is Saquinavir?

Saquinavir is a medicine used to treat HIV. It is usually taken with Ritonavir (an HIV medicine) and other HIV medicines to help it work better.

Saquinavir lowers the amount of virus in the body, helps the immune system stay strong, and reduces the risk of serious infections and cancer.

This treatment does not cure HIV, but taking the medicines regularly helps people live healthier lives and lowers the chance of spreading HIV to others.

Saquinavir mesylate was approved by the FDA (Food and Drug Administration) in 1995. It was introduced and is still used today because it generally causes fewer side effects than some other HIV medicines.

Drug Group

Saquinavir is a type of anti-HIV medicine called a protease inhibitor. It helps treat HIV by blocking an enzyme the virus needs to multiply.

When this enzyme is stopped, the virus cannot make new infectious copies, which lowers the amount of HIV in the body.

Available Doses and Dosage Forms:

Saquinavir is available in two forms:

• Capsules: Light brown and green hard capsules, each containing 200 mg of Saquinavir.

• Tablets: Light orange to brownish-orange film-coated tablets, oval and biconvex, each containing 500 mg of Saquinavir.

Indications:

Saquinavir mesylate, when used together with Ritonavir and other HIV medicines, is approved to treat HIV-1 infection in adults aged 16 years and older.

For Patients

How Does Saquinavir Mesylate Work?

• Saquinavir mesylate is a protease inhibitor used to treat HIV.

• It blocks the HIV protease enzyme, which the virus needs to multiply.

• This action prevents the virus from replicating and lowers the viral load.

• It is usually taken with Ritonavir to improve its effectiveness.

• Saquinavir is used as part of combination antiretroviral therapy to help control HIV infection.

What Is the Dosage of Saquinavir Mesylate?

• Saquinavir mesylate is taken together with Ritonavir.

• The recommended adult dose (16 years and older) is 1000 mg twice daily.

• This dose can be given as five 200 mg capsules per dose or two 500 mg tablets per dose.

• Ritonavir 100 mg is taken twice daily along with Saquinavir.

How Effective Is Saquinavir Mesylate?

When taken with other HIV medicines, Saquinavir lowers the amount of virus in the blood and helps the immune system get stronger by increasing clusters of differentiation 4 (CD4) T cell count. This makes it easier for the body to fight infections.

What Are the Things to Inform the Doctor Before Taking Saquinavir Mesylate?

Before taking Saquinavir mesylate, talk to your doctor about:

• Medical History: Any allergies or reactions to medicines, especially HIV drugs.

• Health Conditions: Liver, heart, kidney problems, diabetes, high cholesterol, bleeding issues, mental health problems, or pancreatitis.

• Current Medications: All prescription, over-the-counter medicines, vitamins, and supplements. Include other HIV medicines.

• Pregnancy and Breastfeeding: Tell your doctor if you are pregnant, planning a pregnancy, or breastfeeding.

• Liver and Heart Health: Share any liver issues or heart problems, like irregular heartbeats.

• Alcohol and Drugs: Inform about alcohol or recreational drug use.

How Is Saquinavir Mesylate Administered?

• Saquinavir mesylate and Ritonavir should be taken within two hours after a meal.

• For patients who cannot swallow capsules, open the Saquinavir mesylate capsules and transfer the contents into an empty container.

• Combine with 15 mL (milliliters) of sugar syrup or sorbitol syrup (for those with type 1 diabetes or glucose intolerance) or three teaspoons of jam in the container.

• Stir the contents with a spoon for 30 to 60 seconds.

• Administer the entire prepared dose. Ensure that suspensions are at room temperature before giving them.

What Are the Side Effects of Saquinavir Mesylate?

Common Side Effects of Saquinavir Mesylate:

• Nausea.

• Vomiting.

• Diarrhea (loose stools).

• Abdominal pain.

• Tiredness.

• Pneumonia (lung infection).

• Changes in body fat distribution.

Dietary Considerations

As such, there is nothing specific, but it is crucial to follow a balanced diet.

Missed Dose:

• If a dose is missed, take it as soon as possible.

• Do not double the dose. If the next scheduled dose is near, continue normally.

Overdose:

There is limited experience with Saquinavir overdose. In cases of Saquinavir overdose, management should involve general supportive measures, including monitoring vital signs and the ECG (electrocardiogram) and observing the patient's clinical status.

Storage:

• Store Saquinavir capsules and tablets at 25°C (77°F).

• Temporary variations between 15 to 30°C (59 to 86°F) are acceptable.

Disposal:

• Dispose of Saquinavir mesylate following local rules and regulations.

• Return unused or expired medicine to a pharmacy or use a drug take-back program.

• Do not flush medications down the toilet unless specifically instructed.

• Ask a doctor, pharmacist, or local authority for proper disposal guidance.

For Doctors

Description:

Chemical Composition:

• Brand Name: Saquinavir mesylate.

• Function: Blocks the protease enzyme of HIV-1 to stop the virus from multiplying.

• Chemical Name: N-tert-butyl-decahydro-2-[2(R)-hydroxy-4-phenyl-3(S)-[[N-(2­quinolylcarbonyl)-L-asparaginyl]amino]butyl]-(4aS,8aS)-isoquinoline-3(S)-carboxamide methanesulfonate.

• Molecular Formula: C38H50N6O5·CH4O3S.

• Molecular Weight: 766.96 (free base: 670.86).

• Appearance: White to off-white, very fine powder.

• Solubility: 2.22 mg/mL in water at 25°C (77°F).

What Are the Pharmacological Aspects of Saquinavir Mesylate?

Pharmacodynamics:

Researchers studied how Saquinavir mesylate affects the heart in 59 healthy adults. They measured the QTcS interval, which shows the time it takes for the heart to recharge between beats, using electrocardiogram tests on day 3.

1. QTcS Interval Changes:

• For people taking Saquinavir mesylate with Ritonavir 1000 mg per 100 mg twice daily, the QTcS interval increased by 18.9 ms compared to a placebo.

• The increase was even more for those taking a higher dose of 1500 per 100 mg twice daily, at 30.2 ms.

• The maximum increase was observed about 12 to 20 hours after taking the medicine.

2. Cmax (Maximum Concentration):

For the higher dose (1500 per 100 mg twice daily), the day 3 Cmax of Saquinavir mesylate was about 1.4 times higher than the approved therapeutic dose in healthy volunteers.

3. QTcS in Healthy Subjects:

The QTcS interval for males and females was calculated using a formula similar to Fridericia’s correction.

4. PR and QRS Interval Prolongations:

• Saquinavir mesylate and Ritonavir caused prolongations in the PR and QRS intervals on Day 3.

• For the 1000 per 100 mg twice daily dose, the increase in PR interval was 28.6 ms, and for the higher dose, it was 38.4 ms.

• The increase in QRS interval was 2.9 ms for the lower dose and 4.4 ms for the higher dose.

5. PR Interval Prolongation (More Than 200 ms):

• About 40 percent and 47 percent of people taking Saquinavir mesylate with Ritonavir at the two doses experienced PR interval prolongation of more than 200 ms on day 3.

• In comparison, only three percent of people in the active control Moxifloxacin group and five percent in the placebo group had a prolongation of PR.

Mechanism of Action of Saquinavir

• Saquinavir works by inhibiting HIV-1 protease. It is an enzyme needed to process viral proteins.

• It works as a substrate analog. It binds to the protease’s active site and blocks its activity.

• This prevents viral proteins from being cleaved. Resulting in immature, noninfectious virus particles.

Pharmacokinetics

Researchers studied how Saquinavir mesylate, a medicine used in HIV treatment, works in both HIV-1-infected and healthy subjects.

Comparison in Healthy vs. HIV-1-infected Subjects:

• Saquinavir levels in healthy people are nearly 50% higher than in HIV-1-infected individuals when taken twice daily.

Absorption and Bioavailability:

• Effectiveness is similar whether taken as a tablet or capsule with low-dose Ritonavir under fed conditions.

• Absorption improves when 600 mg is taken with a high-fat meal.

• Bioavailability may be higher due to incomplete absorption and first-pass metabolism.

Comparison of Different Doses:

• Saquinavir 1000 mg + Ritonavir 100 mg twice daily gives similar blood levels as soft gel capsules 1000/100 mg twice daily.

• These levels are higher than 1200 mg three times daily soft gel capsules.

Food Effect:

• Take Saquinavir with Ritonavir within 2 hours after a meal.

• Food, especially high-calorie meals, increases blood levels of Saquinavir.

Distribution:

• Saquinavir spreads into tissues and is ~98% bound to plasma proteins.

• Very low levels are found in cerebrospinal fluid.

Metabolism and Elimination:

• Mainly broken down by liver enzyme CYP3A4.

• Most of the drug (~88%) is excreted in feces, and ~1% in urine.

• Undergoes extensive first-pass metabolism, rapid clearance, and has a short residence time in the body.

Non-Clinical Toxicity: Carcinogenesis:

Saquinavir showed no signs of causing cancer in rats and mice over a two-year study.

Limited bioavailability in animals resulted in exposures lower than those in humans at the recommended clinical dose of Ritonavir.

Mutagenesis:

Saquinavir demonstrated no mutagenic activity in various tests, including Ames and Chinese hamster lung V79 or HPRT tests.

No chromosomal or primary DNA (deoxyribonucleic acid) damage was observed.

Impairment of Fertility:

In rats, no negative impact on reproductive capabilities or performance was noted in the study.

However, bioavailability differences in animals meant exposures were about 26 percent of those in humans at the recommended clinical dose with Ritonavir.

What Are the Contraindications of Saquinavir Mesylate?

Saquinavir mesylate has several contraindications, and individuals with certain conditions or using specific medications should avoid its use. Contraindications for Saquinavir mesylate include

Hypersensitivity:

• Do not use Saquinavir mesylate if you have had a serious allergic reaction to Saquinavir or any of its ingredients.

Concomitant Medications:

Saquinavir, especially with Ritonavir, should not be taken with certain drugs that are CYP3A substrates, as this can increase their levels and cause serious or life-threatening reactions.

Specific drugs contraindicated with the Saquinavir and Ritonavir combination include, but are not limited to:

• Alfuzosin (alpha 1-adrenoreceptor antagonist).

• Amiodarone, Bepridil, Dofetilide, Flecainide, Lidocaine, Propafenone, and Quinidine (antiarrhythmics).

• Trazodone (antidepressant).

• Rifampin (antimycobacterial agent).

• Dihydroergotamine, Ergonovine, Ergotamine, Methylergonovine (Ergot derivatives).

• Cisapride (GI motility agent).

• Lovastatin, Simvastatin (HMG-CoA reductase inhibitors).

• Pimozide (neuroleptic).

• Sildenafil (PDE5 inhibitor).

• Triazolam is orally administered, as is Midazolam (sedative or hypnotic).

Warnings and Precautions

Drug Interactions:

• Saquinavir + Ritonavir is a strong CYP3A inhibitor. It increases levels of other drugs metabolized by CYP3A.

• Certain drugs are contraindicated due to the risk of serious or life-threatening reactions.

PR Interval Prolongation:

• Can prolong the PR interval, increasing the risk of atrioventricular block.

• ECG (electrocardiogram) monitoring is recommended, especially in patients with heart problems.

QT Interval Prolongation:

• It causes dose-dependent QT prolongation.

• Avoid combining with other QT-prolonging drugs.

• ECG monitoring is important.

Diabetes/Hyperglycemia:

• May cause new or worsening diabetes.

• Monitor blood sugar and adjust insulin or oral diabetes medications as needed.

Hepatotoxicity:

• Can worsen liver disease in patients with pre-existing liver problems.

Hemophilia:

• Spontaneous bleeding may occur.

• Additional factor VIII may be needed.

Hyperlipidemia:

• Can raise the cholesterol and triglyceride levels. So monitor and manage accordingly.

Lactose Intolerance:

• Saquinavir capsules contain lactose. But symptoms are generally not expected.

Resistance and Cross-Resistance:

• Cross-resistance with other HIV-1 protease inhibitors is possible.

• Maintaining viral suppression is critical during therapy.

What Are the Drug Interactions of Saquinavir Mesylate?

The following drugs are to be avoided while taking Saquinavir mesylate:

• Alfuzosin.

• Amiodarone.

• Bepridil.

• Cisapride.

• Lidocaine.

• Pimozide.

• Propafenone.

• Quinidine.

• Rifampin.

• Sildenafil.

• Dofetilide

• Flecainide.

• Simvastatin.

• Trazodone.

• Triazolam.

Pregnancy:

• Limited data in pregnant women. Always use only if the benefits outweigh fetal risks.

Nursing Mothers:

• Do not breastfeed to prevent HIV-1 transmission.

• Saquinavir excretion in human milk is unknown, but breastfeeding may pose serious risks to infants.

Pediatric Use:

• Studied in children 4 months to <16 years with Saquinavir + Ritonavir or Lopinavir/Ritonavir.

• Higher drug levels than adults; long-term outcomes were favorable.

• Dose-dependent QTc and PR prolongation is a concern.

• Safe pediatric dosing below QT/PR thresholds cannot be reliably established.

Geriatric Use:

• Not enough data for patients 65+ years.

• Use caution due to possible liver, kidney, or heart issues and other medications.

Impaired Renal Function:

• Kidney clearance is minor, so initial dose adjustment is not required.

• Caution in severe renal impairment or ESRD, as studies are lacking.

Impaired Hepatic Function:

• Mild or moderate liver problems do not require a dose change, but caution is advised.

• Severe hepatic impairment is a contraindication for Saquinavir + Ritonavir.