Clinical Pharmacology Details


LAMIVUDINE + STAVUDINE + NEVIRAPINE


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Indications & Dose:

Treatment of HIV infection, once patients have been stabilized on the maintenance regimen of nevirapine 200 mg bd, and have demonstrated adequate tolerability to nevirapine. 



ADMINISTRATION


Adults: < 60kg one tablet or 30mg every 12 hours 760 kg, 1tablet or 4 mg every 12 hours.


Children: >14 days: < 30kg 1 mg of starudine/kg every 12 hours > 30kg 1 mg of starudine/kg every 12 hours.


Neonates: < 2 weeks : 500mg of starudine/kg every 12 hours.


Monitoring of patients


Intensive clinical and laboratory monitoring, including liver function tests, is essential, especially at baseline, prior to dose escalation of nevirapine, and at two weeks post dose escalation in some cases, hepatic injury has progressed despite discontinuation of treatment (See Warnings and Precautions).


Dosage Adjustment


Lamivudine


Because it is a fixed-dose combination. Triomune should not be prescribed for patients requiring dosage adjustment, such as those with low body weight (<50 kg).


Stavudine


Patients should be monitored for the development of peripheral neuropathy, which is usually manifested by numbness, tingling or pain in the feet or hands. If these symptoms develop during treatment stavudine therapy should be interrupted. Symptoms may resolve if therapy is withdrawn promptly.


In some cases, symptoms may worsen temporarily following discontinuation of therapy. If symptoms resolve completely, patients may tolerate resumption of treatment at one half the recommended dose.


Since Triomune is a fixed dose combination, it cannot be used under these circumstances.


Nevirapine


Triomune should be discontinued if patients experience severe rash or a rash accompanied by constitutional findings (See Warnings and Precautions). Patients experiencing rash during the 14-day lead in period of 200 mg/day should not have their nevirapine dose increased or start therapy with Triomune until the rash has resolved (see Warnings and Precautions).


If clinical hepatitis occurs, navirapine should be permanently discontinued and not restarted after recovery.


Renal Impalment


The dose of both lamivudine and stavudine should be reduced for patients with CrCL < 50 mL/min. for nevirapine, dose reduction is required when CrCL < 20 mL/min. Additional doses or nevirapine are required for patients on dialysis. Since Triomune is a fixed dose combination, it should not be prescribed for these patient populations.


Hepatic impairment


No dose adjustment for lamivudine is required for patients with impaired hepatic function. Safety and efficacy of lamivudine have not been established in the presence of decompensated liver disease.


Stavudine pharmacokinetics were not altered in 5 non HIV infected patients with hepatic impairment secondary to cirrhosis (Child-Pugh classification B or C) following the administration of a single 40-mg dose.


Increased nevirapine levels and nevirapine accumulation may be observed in patients with serious liver disease. Nevirapine should not be aministered to patients with severe hepatic impairment.


Pregnancy


Lamivudine, stavudine and nevirapine are all classified under category C. There are no adequate and well-controlled studies in pregnant women. Triomune should be used during pregnancy only if the potential benefits outweigh the potential risk. 


 

Contraindications:

Side Effects:

Lamivudine


Observed During Clinical Practice: The following events have been identified during post-approval use of lamivudine. Because they are reported voluntarily from a population of unknown size, estimates of frequency cannot be made. These events have been chosen for inclusion due to a combination of their seriousness, frequency of reporting, or potential causal connection to lamivudine.


Body as a whole: Redistribution/accumulation of body fat.


Digestive: Stomatitis.


Endocrine and Metabolic: Hypercalcaemia.


General: Weakness


Haemic and Lymphatic: Anaemia (including pure red cell aplasia and severe anaemias progressing on therapy), lymphadenopathy, splenomegaly.


Hepatic and Pancreatic: Lactic acidosis and hepatic steatosis, pancreatitis, posttreatment exacarbation of hepatitis B (see 

Cautions:

Precautions:

Hypersensitivity: Anaphylaxis, urticaria.


Musculoskeletal: Muscle weakness, CPK elevation, rhabdomyolysis


Nervous: Paraesthesia, peripheral neuropathy


Respiratory: Abnormal breath sounds/wheezing.


Skin: Alopecia, rash, pruritus Stavudine


Fatal lactic  acidosis has occurred in patients treated with stavudine in combination with other antiretroviral agents. Patients with suspected lactic acidosis should immediately suspend therapy with stavudine. Permanent discontinuation of stavudine should be considered for patients with confirmed tactic acidosis. Stavvudine therapy has rarely been associated with motor weakness, occurring predominantly in the setting of lactic acidosis. If motor weakness develops, stavudine should be discontinued.


Stavudine therapy has also been associated with peripheral sensory neuropathy, which can be severe, is dose related, and occurs more frequently in patients being treated with neurotoxic drug therapy. Including didanosine, in patients with advanced HIV infection, or in patients who have previously experienced peripheral neuropathy.


Patients should be monitored for the development of neuropathy, which is usually manifested by numbness, tingling, or pain in the feet or hands. Stavudine-related peripheral neuropathy may resolve if therapy is withdrawal promptly. In some cases, symptoms may worsen temporarily following discontinuation of therapy. If symptoms resolve completely, patients may tolerate resumption of treatment at one-half of the dose. If neuropathy recurs after resumption, permanent discontinuation of stavudine should be considered.


When stavudine is used in combination with other agents with similar toxicities, the incidence of adverse events may be higher than when stavudine is used alone. Pancreatitis, peripheral neuropathy, and liver function abnormalities occur more frequently in patients treated with the combination of stavudine and didanosine, with or without hydroxyurea. Fatal pancreatitis and hepatotoxicity may occur more frequently in patients treated with stavudine in combination with didanosine and hydroxyurea.


Observed During Clinical Practice


The following events have been identified during post-approval use of stavudine. Because they are reported volutarily from a population of unknown size, estimates of frequency cannot be made. These events have been chosen for inclusion due to their seriousness, frequency of reporting, causal connection to stavudine, or a combination of these factors.


Body as a Whole: Abdominal pain, allergic reaction, chills/fever, and redistribution/accumulation of body fat.


Digestive Disorders: Anorexia


Exocrine Gland Disorders: Pancreatitis (including cases)


Hematologic Disorders: Anaemia, leukopenia and thrombocytopenia


Liver: Lactic acidosis and hepatic steatosis, hepatitis and liver failure


Musculoskeletal: Insomnia, severe motor weakness often reported in the setting of lactic acidosis.


Nevirapine


clinical practice has shown that the most serious adverse reactions associated with navirapine are clinical hepatitis/hepatic failure. Stevens-Johnson syndrome, toxic epidermal necrolysis and hypersensitivity reactions. clinical hepatitis/hepatic failure may be isolated or associated with signs of hypersensitivity which may include severe rash or rash accompanied by fever, general malaise, fatigue, muscle or joint aches, blisters, oral lesions, conjuctivitis, facial oedema, and/or hepatitis, eosinophilia, granulocytopenia, lymphadenopathy, and renal dysfunction.


Severe and life-threatening hepatotoxicity, and fatal fulminant hepatitis have been reported in patients treated with navirapine. Hepatic adverse events have been reported to occur more frequently during the first 18 weeks of treatment, but such events may occur at any time during treatment.


In controlled clinical trails, clinical hepatic events regardless of severity occurred in 4.0% (range 2.5% to 11.0%) of patients who received navirapine and 1.2% of patients in control groups. Transaminase elevations (ALT or AST > 5X ULN) were observed in 8.0% of patients receiving nevirapine and 6.2% of patients in control groups in clinical trails. In a retrospective analysis of controlled and uncontrolled clinical trails, patients with higher CD4 counts at initiation of nevirapine therapy, particularly women, were at greater risk for acute symptomatic hepatic events, including death, especially in the first six weeks of therapy Patients with chronic hepatitis B or C infection were at higher risk for later hepatic events.


The most common clinical toxicity of nevirapine is rash. Severe or life threatening rash occurred  in approximately 2% of nevirapine treated patients, most frequently within the first 6 weeks of therapy. Rashes are usually mild to moderate, maculopapular erythematous cutaneous eruptions, with or without pruritus, located on the trunk, face and extremities. Women tend to be at higher risk for development of nevirapine associated rash.


With respect to laboratory abnormalities, liver function test abnormalities (SGOT, SGPT) were observed more frequently in patients receiving nevirapine than in controls. Asymptomatic elevations in GGT levels occur frequently but are not a contraindication to continue nevirapine therapy in the absence of elevations in other liver function tests. Other laboratory abnormalities (billirubin, anaemia, neutropenia, thrombocytopenia) were observed with similar frequencies in clinical trails comparing nevirapine and control regimens.


Because clinical hepatitis has been reported in nevirapine-tested patients, intensive clinical and laboratory monitoring, including liver function tests, is essential at baseline and during the first 18 weeks of treatment. Monitoring should continue at frequent intervals thereafter, depending on the patient’s clinical status. In addition to the adverse events identified during clinical trials, the following events have been reported with the use of Nevirapine in clinical practice.


Body as a Whole: fever, somnolence, drug withdrawal.


Gastrointestinal: vomiting


Liver and Biliary: Jaundice, fulminant and cholestatic hepatitis, hepatic necrosis, hepatic failure.


Haematology: anaemia, eosinophilia, neutropenia


Musculoskeletal: arthralgia


Neurologic: paraesthesia


Skin and appendages:


allergic reactions including anaphylaxis, angloedema, bulours eruptions, ulcerative stomatitis and urticaria have all been reported. In addition, hypersensitivity syndrome and hypersensitivity reactions with rash associated with constitutional findings such as fever, blistering, oral lesions, conjunctivitis, facial oedema, muscle or joint aches, general malaise, fatigue or significant hepatic abnormalities plus one or more of the following hepatitis, eosinophilia, granulocytopenia, lymphadenopathy and/or renal dysfunction have been reported with the use of nevirapine.


OVER DOSAGE


Lamivudine


There is no known antidote for lamivudine. It is not known whether lamivudine can be removed by peritoneal dialysis or hemodialysis.


Stavudine


Experience with adults treated with 12 to 24 times the recommended daily dosage revealed no acute toxicity. Complications of chronic overdosage include peripheral neuropathy and hepatic toxicity. Stavudine can be removed by hemodialysis.


 

Interaction:

Warnings:

Adverse Effects:

Lactations:

It is recommended that HIV-infected mothers doe not breast-feed their infants to avoid risking postnatal transmission of HIV infection. It is not known whether stavudine or lamivudine are excreted in human milk. Nevirapine is present in breast milk.


Paediatrics


Triomune is not intended for use in paediatric patients

Special Precautions:

Counselling:

Side Effects Or Adverse Reactions:

Patient And Carer Advice: