Drug interactions - summary-

Atazanavir + Tenofovir / Tenofovir + Atazanavir

Concurrent use increased AUC and Cmax concentrations. Do not coadminister without
the addition of ritonavir

Indinavir + Tenofovir / Tenofovir + indinavir

Coadmin increased Cmax but AUC remained unchanged.
Cmax of indinavir decreased 

Lopinnavir/ritonavir  + tenofovir

Concurrent use increased tenofovir AUC . Monitor closely

Tenofovir + Abacavir

Concurrent use increased  abanavir Cmax  but AUC  remained unchanged

Tenovir + acyclovir, dipivoxil, cidofovir, gangciclovir, valacyclovir, valganciclovir/
 acyclovir, dipivoxil, cidofovir, gangciclovir, valacyclovir, valganciclovir + tenovir

Coadmin of tenofovir with drugs that reduce renal function or compete for active  tubular
secretion eg acyclovir, adefovir, dipivoxil, cidofovir, gangciclovir, valacyclovir,
valganciclovir may increase serum concentrations of tenovir and increase  the
concentrations of other renally eliminated drugs.

Adverse Reactions-

CNS  -     anxiety   5%    asthenia   5%    depression  10%     dizziness  3%    

                headache 12%   insomnia  4%       peripheral neuropathy  1%

Dermatologic -      rash   16%    

GI -    adominal pain   6%     diarrhoea    10%    dyspepsia   3%     vomiting   7%
         

Metabolic -     lipodystrophy  1%

Musculoskeletal -   arthalgia   4%     back pain   8%   myalgia  3%

Respiratory -   pneumonia    4%

Miscellaneous -   fever   7%    pain  12%

Special precautions/Warnings-

Lactic acidosis/severe hepatomegaly with steatosis-  suspend treatment  with tenofovir if any patient who develops clinical or laboratory findings suggestive of lactic
acidosis or pronounced hepatotoxicity which may include hepatomegaly and steatosis
even in absence of transaminase elimination

Exacerbation of hepatitis after discontinuation of treatment - monitor hepatic function
closely with both clinical and laboratory follow-up for at least for several months in
patients who discontinue antihepatitis B therapy, including tenofovir. if necessary
resumption of hepatitis B therapy may be warrented

HIV and HBV coinfection- because of the risk of development of of HIV -1 resistence
only use tenofovir in HIV-1 and HBV conifected patients as a part of antiretroviral
combination regimen

Renal impairment impairment - No safety data available in patients with renal function impairment who received. Ascess potential benefit against potential risk of renal toxicity.

Pregnancy- use tenofovir only if needed.

Lactation- instruct mothers not to breast feed if they are receiving tenofovir

Children- safety and efficacy in children younger than 18 years of age have not
been established.

Monitoring-  consider bone monitoring for HIV infected patients who have a history of
pathological bone fractures or at risk for osteoporosis

Monitor patients with a history of renal function impairment and patients receiving
concomittant nephrotoxic agents for changes in serum creatinine and phosphorus

Indication-

Chronic Hepatitis B

Dosage-
Adult 18 year - 300mg once daily

1. Advice patients not to discontinue tenofovir without first informing their doctor.

2. Inform patients with HIV 1 infection with or without HBV coinfection that it is important
to take tenofovir with combination therapy

3. It is important to tenofovir on a regular dosing schedule and to  avoid missing doses.

4. Lactic acidosis and severe hepatomegaly with steatosis including fatal cases have been
reported. suspend treatment with tenofovir in any patient who deelops clinical symptoms
suggestive of lactic  acidosis  or pronounced hepatoxiciy

5. In patients with chronic hepatitis B it is important to obtain HIC antibody testing prior
to initiating tenofovir

6. Renal impairment including cases of acute renal failure has been reported. Tenofovir
should be avoided  with concurrent  or recent use a nephrotoxic agent. Dosing interval
of tenofovir may need to adjusted in patients with renal impairment.

6. Do not administer tenofovir in combination with adefovir

Pregnancy-
Use tenofovir only if needed.

Lactation-
Instruct mothers not to breast feed if they are receiving tenofovir

Children-
Safety and efficacy in children younger than 18 years of age have not
been established.