Drug profile of Synthivan
Synthivan is an anti-viral medication which is containing atazanavir & ritonavir as an active moiety.
Synthivan tablets are fixed dose combination, which is categorized as protease inhibitor.
Atazanavir is a chemically classified as azapeptide, which is containing bis-aryl substituent on hydrazine moiety exhibits anti-retroviral activity against wild type & mutant forms of HIV protease.
Ritonavir is also a protease enzyme inhibitor, which is a peptidomimetic agent for both HIV-1 & HIV-2 type infections.
Brand name: Synthivan
Active substance: Atazanavir & Ritonavir
Strength: 300mg & 100mg respectively
Pack: 30 tablets in a container
Classified as: Anti-retroviral drug
Prescribing information of Synthivan
Synthivan tablet containing active moiety are classified as protease inhibitor, whch is involed in the treatment of HIV-1 infections.
Mechanism of Synthivan
HIV protease enzymes which is includes in division of auxiliary and multiplicative proteins that may deliver from significant HIV qualities, similar to choke and pol. This action of protein ought to be diminished because of repressing the protease chemical by ritonavir, a functioning substance of Ritomune tablets.
Gal: cover the proteins confused in center and nucleocapsid.
Pol: cover the turnaround transcriptase, ribonuclease H, integrase and protease.
The division of lady buddy polyprotein ought to be counteracted by ritonavir which prompts generation of youthful and non irresistible viral particles.
Atazanavir specifically restrains the infection particular preparing of viral Gag and Gag-Pol polyproteins in HIV-1 contaminated cells by official to the dynamic site of HIV-1 protease, hence keeping the arrangement of develop virions. Atazanavir isn't dynamic against HIV-2.
Atazanavir is administering with food will leads to increase the bioavailability and decreases the pharmacokinetics variability.
The mean oral bioavailability of atazanavir is 60 to 68%.
The absorption of atazanavir is occurs very quickly; with Tmax value is 2.5 hours.
After administration of ritonavir, the maximum plasma concentration is reaches within 2 hours & 4 hours in both fasted & non fasted condition.
The bio availability of ritonavir should be reduced by food.
The Cmax value is 0.84ng/ml ± 0.39ng/ml
The Cmin value is 6.6ng/ml ± 2.4ng/ml/hr.
The volume of distribution of ritonavir is 20 to 40L.
The CSF plasma ratio of ritonavir is 0.52
The semen plasma ratio <0.04
Ritonavir is highly binds to human plasma protein by 98 to 99%.
Atazanavir is binds to serum proteins by 86%.
Ritonavir has major metabolite such as Isopropylthiazole oxidation.
The major isoenzyme used for the metabolism of ritonavir is CYP3A.
Atazanavir is highly metabolized, in liver.
The biotransformation of atazanavir majorly occurs by undergoing Monooxygenation & Dioxygenation.
The elimination process of ritonavir is majorly via feces & urine.
The mean terminal half life period of ritonavir is 3 to 5 hours.
The mean terminal half life period of atazanavir is relatively 7 hours.
The elimination half life through liver impaired is 12.1 hours.
When to take the Synthivan
Synthivan tablets should be administered with food.
Synthivan tablets are fixed dose combination; it should not be broke, chew or crush.
Dosage regimens of Synthivan
Atazanavir should not used alone; it should be combined with ritonavir which is majorly prescribed for therapy experienced adult patients with preceding virologic failure.
The higher dose of ritonavir will cause reducing the safety profile of atazanavir.
Before starting the treatment with atazanavir;
Patients who are going to receiving the atazanavir should be performed with renal function test periodically for both prior and during the therapy.
Serum creatinine, creatinine clearance, urine analysis should be checked frequently.
Hepatic function test is also performed before starting & during the treatment.
The prescribed dose of Synthivan is one tablet should be administered as a single dose by combining with any of the following drugs like;
H2 receptor antagonist: The gastric regulator drug should not be exceeding a dose equal to famotidine 40mg as two times a day. Synthivan tablets should be concurrently administered with & or at least 10 hours after the dose of H2 receptor antagonist.
Proton pump inhibitors: The administration of proton pump inhibitor should not superior a dose equal to Omeprazole 20mg and it should be taken 12 hours before the dose of Synthivan tablets.
In therapy experienced patients (adults):
The recommended dose is one tablet of Synthivan should be administered as a single dose.
H2 receptor antagonist: The gastric regulator drug should not be exceeding a dose equal to famotidine 20mg as two times a day. Synthivan tablets should be concurrently administered with & or at least 10 hours after the dose of H2 receptor antagonist.
If patient taking H2 receptor antagonist, Synthivan tablets should be taken with food.
If patients administered tenofovir & H2 receptor antagonist concurrently, then Synthivan tablets should not be recommend.
In therapy experienced patients who are getting Synthivan tablets, proton pump inhibitor should not be recommended.
Synthivan tablets should not be administered with efavirenz, because of reducing atazanavir exposure.
In pregnant women:
The recommended dose of Synthivan is;
In both new commenced or already treated patients:
The prescribed dose is one Synthivan tablet should be administered as a single dose.
In case of combination of H2RA or tenofovir DF, the recommended dose is 400mg of atazanavir & 100mg of ritonavir should be recommended as a single dose.
In therapy experienced pregnant patients during 2nd or 3rd trimester, atazanavir should not be suggested.
In renal impairment:
In severe renal damage patients who are not tolerated to hemodialysis, no dosage adjustment should be recommended.
In therapy naïve patients with final stage of renal disease, the dose of Synthivan tablets should be reduced.
In HIV experienced patients with final stage of renal disease, the Synthivan tablets should not be recommended.
In hepatic impairment:
For mild to moderate liver damaged patients, Synthivan tablets should be recommended for administration.
In severe condition, Synthivan tablets should not be used.
Synthivan caused side effects
The major adverse effects of Synthivan tablets are;
Cardiac conduction abnormalities
Increased bilirubin levels
Chronic kidney disease
The common side effects;
Increased AST, ALT
Increased creatine kinase
Post marketing reports:
Liver function abnormalities
Drug- drug interaction
Co administration of Synthivan tablets with drugs formerly metabolized by CYP3A or UGT1A1, results as elevation of plasma concentration of these drugs because atazanavir is an inhibitor of CYP3A & UGT1A1.
Synthivan administered with substrate of CYP2C8, interaction is not identified. Atazanavir is a weak inhibitor of CYP2C8.
Synthivan with CYP3A4 inducers causes decreasing the plasma concentration of atazanavir and leads to loss of effect of atazanavir.
The solubility of atazanavir is depends on pH levels, if co administration of Synthivan with gastric regulator drugs leads to cause decreased plasma concentration of atazanavir.
Synthivan with Didanosine buffered tablets, causes decreasing the effect of concentration of atazanavir.
Synthivan tablets with Didanosine EC results as decrease in concentration of Didanosine.
Tenofovir DF leads to alter the AUC & Cmin value of atazanavir, in adults the recommended odse of 300mg atazanavir, with 100mg of ritonavir should be given with tenofovir DF 300mg ledas to cause increasing concentration of tenofovir.
Synthivan tablet should not be combined with efavirenz, leads to decrease the concentration of atazanavir.
Synthivan with boceprevir, this combination causes reducing the effect of concentration of component in Synthivan.
Gastric regulator drugs should not be simultaneously administered with Synthivan tablets.
Synthivan with anti-arrhythmia drugs causes increasing effect of concentration of these drugs.
Synthivan tablets are combined use with warfarin, leads to cause increasing concentration of warfarin.
Anti-depressants tablets are combined with Synthivan tablets may results as increasing effect of concentration of anti-depressants.
Anti-epileptics with Synthivan cause increasing concentration of these drugs.
Synthivan with anti-gout, benzodiazepines, or anti-psychotic drugs may leads to increasing concentration of these following drugs.
Synthivan plus calcium channel blockers, lipid lowering drugs, or Immuno suppressants cause increasing effect of concentration of these drugs.
Food drug interaction
Caffeine causes minor drug interactions.
Intake of Synthivan tablets with food leads to increase the level of atazanavir in the body.
For proper absorption of Synthivan, should be administered with or immediately after the intake of food.
Synthivan should be contraindicated for;
Patients suffered with hypersensitivity reaction, because patients are contraindicated to the component present in the Synthivan.
Synthivan is contraindicated to strong CYP3A inducers; it may causes loss of effectiveness of atazanavir.
Some drugs are contraindicated to Synthivan like;
Rifampin: decreases the concentration of atazanavir
Irinotecan: atazanavir inhibits the UGT1A1, which is responsible for metabolism of Irinotecan. This results as increasing concentration of Irinotecan
Lurasidone: life threatening condition may occur
St johns wort
Some adverse effects may occur during therapy using with Synthivan tablets;
Cardiac conduction abnormalities:
This is due to prolonged elevation of PR intervals by atazanavir.
Monitor with ECG frequently for reducing the adverse effects.
Rash is the one of the most important effect occurred on skin.
Atazanavir should be stopped during rashes present.
Symptomatic elevation of bilirubin occurs by prohibits the UDP glucuronosyl transferase.
Dose reduction is not possible, once the level of bilirubin is elevates stop the treatment.
During the Synthivan treatment patient should be monitored with renal function test.
Nephrolithiasis & cholelithiasis:
To overcome the problem, patient must be provided with additional management.
Temporary postponement or discontinuation of therapy is occurring.
Adverse effects may occur due to drug interactions, like;
Synthivan with drugs are metabolized by CYP3A or CYP3A causes increased concentration of these drugs.
Check the blood glucose level periodically
Patient must be prescribed with dose adjustment insulin or oral hypoglycemic agents.
Diabetes ketoacidosis should be occurred after discontinue the treatment.
Immune reconstitution syndrome: Stop the Synthivan therapy.
Redistribution of fat occurred in the body leads to cause obesity.
To overcome the problem in severe condition, discontinue the treatment.
Severe bleeding occurs, discontinue the protease inhibitor therapy.
Pregnancy and lactation
Pregnancy category: B
Atazanavir should be used in limited number of pregnant women.
Synthivan tablets should be used with caution only after knowing the risk factor associated with the treatment.
Breast feeding should not be allowed while the patient undergoing HIV-1 infection therapy.
Storage and handling
Synthivan tablet container should be kept in cool & dry place.
Missed dose of Synthivan should be avoided.
In case of missed dose, patient must be consult with physician and follow the instructions.
Maintain the regular dosing schedule.
In Synthivan over dosage condition patient should be;
Provide with supportive measures
Gastric lavage or emesis should be provided
Activated charcoal is used for removing the unabsorbed dose of Synthivan
Dialysis is not successive, because ritonavir is highly metabolized and binds to human plasma protein in higher extent.