Nov. 2011, Volume 8, No. 11 (Serial No. 84), pp. 661–666
Journal of US-China Medical Science, ISSN 1548-6648, USA
Acute Pharmacokinetics of First Line Anti-tuberculosis Drugs in Patients with Pulmonary Tuberculosis and in Patients with Pulmonary Tuberculosis Co-infected with
Pierre Mugabo1, Mogamat Shafick Hassan2 and R. Slaughter3
1. Department of Pharmacology, University of the Western Cape, Cape Town, South Africa 2. Department of Health Sciences, Cape Peninsula University of Technology, Cape Town, South Africa 3. Department of Pharmacy Practice, College of Pharmacy and Health Sciences. Wayne State University, Detroit, Michigan 48202, Abstract: Background: The aim of this study was to compare the pharmacokinetics of antituberculosis drugs in patients with pulmonary tuberculosis (PTB) and in patients with PTB and HIV during the first 24 h of treatment. Methods: Designed a case-control study, it compares the pharmacokinetics of first line antituberculous drugs, in HIV-positive (cases) and HIV-negative (control) patients both presenting with pulmonary tuberculosis. Blood samples were collected before and 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 8, 12 and 24 h after administration of drugs. Drugs plasma levels were tested using HPLC assays. Results: Fourteen HIV positive (7 males and 7 females) and 17 HIV negative (9 males and 8 females) enrolled. Rifafour, a combination tablet including rifampicin, isoniazid, pyrazinamide and ethambutol was used in HIV positive patients, CD4 counts were significantly lower, renal function mildly decreased in 85% patients and moderately decreased in 7% patients. Liver function was normal in both groups. None of these patients was on other drug therapy. In the HIV positive group isoniazid T1/2 and AUC were decreased and Cl increased whereas Tmax and Cmax were unchanged. Pyrazinamide Tmax and Cmax were significantly decreased in HIV positive patients and no significant changes were noticed in the T1/2, AUC and CL. Conclusion: The study suggest that ethambutol, pyrazinamide and rifampicin pharmacokinetics was not affected by HIV infection and that isoniazid disposition is affected by HIV. Key words: Pharmacokinetics, rifampicin, isoniazid, ethambutol, pyrazinamide, HIV infection.
new smear-positive patients with TB in South Africa
was 64%. Therapeutic response is influenced by the
Tuberculosis (TB), in sub-Saharan Africa, remains a
method of administration with Directly Observed
leading cause of mortality in HIV infected patients and
Treatment (DOT) estimated to have averted 8 million
is the leading cause of death in South Africa where the
deaths related to TB . Appropriate management of
life expectancy is only 49 years of age. The country has
TB in South Africa is particular important because of
the highest incidence of HIV/AIDS world wide with an
the high incidence of HIV, a known risk factor for
estimated 5.7 million people infected in 2009 [1, 2].
development of TB, and the high rates of MDR-TB
Co-infection of HIV/AIDS patients with TB is a
with over 6,000 cases expected to be treated in South
substantial health problem. The cure rate in 2008 of
Drug treatment of tuberculosis consists of 2 months
Corresponding author: Pierre Mugabo, professor, research
of isoniazid, refiampin, pyrazinamide and ethambutol
fields: pharmacokinetics of antituberculous and antiretroviral drugs, cardiovascular pharmacology. E-mail: followed by 4 months of rifampin and isoniazid . firstname.lastname@example.org.
662 Acute Pharmacokinetics of First Line Anti-tuberculosis Drugs in Patients with Pulmonary Tuberculosis and in Patients with Pulmonary Tuberculosis Co-infected with HIV
Therapeutic response is related to serum concentrations
consent to join the study, patients were admitted to the
of drugs received with poor outcomes associated with
Karl Bremer Hospital in Cape Town (South Africa), in
low pyrazinamide and isoniazid concentrations [5, 6].
the evening before the start of TB treatment. They were
Lower treatment outcomes are seen in patients
excluded from the study on request by the patient, if
co-infected with HIV , which may explain why the
they were critically ill and in case of previous exposure
to anti-TB drugs. Other exclusion criteria included the
There have been a few studies that have investigated
presence of chronic disease such as diabetes mellitus,
the influence of AIDS on the absorption of drugs used
hypertension and cardiac failure, as determined by
to treat tuberculosis. Some authors concluded that drug
malabsorption may contribute to the emergence of
acquired drug resistance [7–10]; and they have advocated for routine therapeutic drug monitoring of
For the initial phase of treatment (2 months)
antituberculous drugs in HIV-infected patients, Rifafour® e-200 tablets were used. Each tablet particularly those with advanced HIV disease [7–10].
contains rifampicin (RIF) 120 mg, isoniazid (INH) 60
Other studies found that the call for screening of
mg, pyrazinamide (PZA) 300 mg and ethambutol (ETH)
antimycobacterial drug levels in HIV-infected patients
200 mg. Patients weighing 30–50 kg body weight (BW)
with pulmonary tuberculosis is still premature since no
received 4 tablets Rifafour® e-200 daily dose. Those
impairment in the bioavailability of antituberculosis
with a body weight (BW) > 50 kg received 5tablets
Rifafour® e-200 daily dose. For the continuation phase
The aim of this study was to describe the
of treatment Rifinah ® – 150 and Rifinah ® – 300 were
pharmacokinetics of the first line anti-tuberculosis (TB)
used. Each Rifinah ® – 150 tablet contains RIF 150 mg
drugs during the first 24 hours after drug administration
and INH 100 mg. Each Rifinah ® – 300 tablet contains
in patents infected with pulmonary tuberculosis (PTB)
RIF 300 mg and INH 150 mg. Patients weighing less
and compare the pharmacokinetic parameters obtained
than 50 kg received 3 tablets of Rifinah ® – 150 and
in patients co-infected with PTB and HIV.
those with a BW ≥ 50 kg received 2 tablets of Rifinah ® – 300. Tablets were taken in front of a nurse every
2. Patients and Methods
day, five days a week (Monday to Friday). Each patient
2.1 Study Design, Subjects, Inclusion and Exclusion
was also given pyridoxine 25 mg daily in order to
prevent peripheral neuropathy due to INH. All tablets were supplied by Aventis Pharma (Pty) Ltd, 2 Bond
Designed a case-control study, the study compares
Street, Midrand 1685, South Africa. The acetylation
the pharmacokinetics of first line antituberculous drugs,
in HIV-positive (cases) and HIV-negative (control) patients both presenting with pulmonary tuberculosis.
The study involved male and female patients without
The following morning, after an 8-hour overnight
previous history of TB, 18 to 60 years old, with sputum
fast, blood samples were collected for base line tests
microbiology test positive for Mycobacterium including liver function tests (LFTs), renal function
tuberculosis (MTB) which was sensitive to rifampicin
tests (RFTs), full blood count (FBC), CD4 counts and
(RIF), isoniazid (INH), ethambutol (ETH) and plasma concentrations of the anti-TB drugs. Rifafour
pyrazinamide (PZA). Patients were recruited from their
was administered to patients for the first time using the
home area TB clinics where they had just been tested
dosages recommended by the Department of Health.
for HIV after counseling. After informed and written
Acute Pharmacokinetics of First Line Anti-tuberculosis Drugs in Patients with Pulmonary Tuberculosis 663 and in Patients with Pulmonary Tuberculosis Co-infected with HIV
Then blood samples were collected for TB drugs
patient was plotted using Graph Pad Prism program.
plasma levels determination at 0.5, 1, 1.5, 2, 2.5, 3, 3.5,
Drugs pharmacokinetic parameters were calculated
4, 4.5, 8, 12 and 24 hours after drug administration.
based on the non-compartmental analysis (NCA) as
Patients were served the same breakfast 1 hour after the
beginning of the treatment. They were also offered the
2.5.1 Maximum Concentration and the Time to
same meal at lunch and super time. The following
morning, the 24 hours blood sample for TB drug
The maximum concentration (Cmax) and the time to
plasma levels determination was collected before
reach the maximum concentration (Tmax) were obtained
breakfast and administration of the following morning
directly from the plasma concentration-time profile.
anti-TB drugs. Blood samples for determination of TB
drugs plasma levels were collected in a heparinized
The half-life (T½) was calculated using the formula:
vacutainer tube from an intravenous catheter fixed on a
T½ = 0.639/Ke and Ke was determined from the
forearm vein of the patient prior to dosing and
terminal slope of the ln-concentration vs time curve.
centrifuged immediately, with the plasma stored in a
minus 20˚C freezer for no more than 12 hours.
Thereafter, it was stored in a minus 80˚C deep freezer
The area under the plasma concentration-time curve
from zero to 24 hours (AUC0-24) was calculated by the
trapezoidal method using Graph Pad Prism software.
The following laboratory tests were conducted at the
The apparent total body clearance (Cltot) was
calculated using the following formula: Cltot = Dose/
(NHLS) Green Point Lab (Cape Town–South Africa)
AUC0-24. Low Cmax values were defined using the
for each patient: liver function tests (LFTs), renal
following method reported by Jordan W. Tapero et al.
function tests (RFTs), full blood counts (FBC), sputum
: isoniazid, < 3 µg/mL (300 mg dose); rifampicin,
microscopy after Auromine or Ziehl-Neelsen stains. If
<8 µg.mL (weight –adjusted dose, 450 or 600 mg);
mycobacteria were observed, susceptibility tests were
pyrazinamide, <35 µg/mL (median dose, 35 mk/kg);
determined forall first — line anti TB agents mentioned
and ethambutol, <2 µg/mL (median dose, 21 mk/kg).
above HIV test (Elisa) was done at the University of
Very low Cmax values were defined as follows:
Cape Town (UCT) Virology Department for each
isoniazid, <2 µg/mL (300 mg dose) or <3 µg/mL (400
patient. Plasma levels were performed using high
mg dose); rifampicin, <4 µg/mL; pyrazinamide, <20
performance liquid chromatography (HPLC) assay methods. The lower limit of quantification for all four
µg/mL; and ethambutol, <1 µg/mL. Delayed
drugs was 0.05 µg/ml. The linear range for isoniazid
absorption was defined as a Tmax >3 h.
and rifampicin was 0.05–30 µg/ml and for
2.5.5 Ethical and Statistical Considerations
pyrazinamide it was 0.05–100 µg/ml. All four drugs
The study was conducted according to the
declaration of Helsinki and ICH guidelines. The protocol was approved by the ethics committee of the
2.5 Determination of Pharmacokinetic Parameters
University of the Western Cape. Permission to conduct
After determination of rifampicin, isoniazid,
the study was granted by the medical superintendent of
pyrazinamide and ethambutol plasma concentrations,
Karl Bremer Hospital. The information obtained
the plasma concentration-time profile for each drug by
during the study was treated as confidential.
664 Acute Pharmacokinetics of First Line Anti-tuberculosis Drugs in Patients with Pulmonary Tuberculosis and in Patients with Pulmonary Tuberculosis Co-infected with HIV
For each of 4 drugs responses for those who are
As indicated in Table 1, the age distribution is
HIV Positive were compared to those who were
similar in both groups. The mean age is 33.06±10.12 in
negative on each of the 9 parameters. Some of the
HIV negative group (control) and 35.14±12.05 in HIV
parameters are related, so test results are not
independent. Nevertheless there are many tests being
Out of 14 HIV-positive patients, 9 were stage 3
done so a more stringent level of significance was used
(WHO staging system) and 5 were stage 4 (WHO
(a p value of < 0.01 rather than the customary 0.05 was
staging system). The mean CD4 cells was 356.38 and
required for significance). In many cases the the mean period of HIV infection was 5.9 yrs. distribution of the measurements was skewed and
The CD4 counts were significantly lower in the HIV
decidedly non-normal. Consequently groups were
positive patients (cases) than in the HIV negative
compared using the Wilcoxon Rank Sum test.
patients (control). In the HIV control group, the renal function was normal. However, in cases group, the
renal function was mildly decreased in 85.71% of
Thirty one (31) patients were involved in the study
patients, moderately decreased in 7.14% of patients
with 14 (7 males and 7 females) patients determined to
and normal in 7.14% of patients. The hepatic function
be HIV positive (cases) and seventeen patients (9 males
tests were normal in both groups. None of these
and 8 females) HIV negative (control) (Table 1). All of
them were infected with Mycobacterium tuberculosis
Tables 2a, 2b, 2c and 2d provide the descriptive
(MTB) sensitive to anti-TB drugs used. During the
statistics for the pharmacokinetic parameters for the
intensive phase (first 2 months) rifafour, a combination
test drugs in HIV positive and HIV negative patients.
tablet including rifampicin 120 mg, isoniazid 60 mg,
In general the presence of HIV did not impact the
pyrazinamide 300 mg and ethambutol 200 mg, was
disposition of ethambutol, pyrazinamide and
used at the dose of 4 tablets daily five days a week
rifampicin. The one exception was isoniazid which
(Monday to Friday) for patients under 50 kg body
showed a modest effect of HIV on its disposition. A
weight and 5 tablets daily for patients weighing 50 kg
statistical reduction in Tmax in HIV positive patients
was observed and borderline changes in half-life, AUC
The median body weight was 54 (range 51–60) kg in
0-24 and Cl. It appears that the presence of HIV
may modestly decrease AUC and half-life which is
HIV-positive patients (cases) and 56 (range 51–65) kg
consistent with either an observed increase in clearance
Table 1 Demographics, renal and hepatic function data. 4. Discussion and Conclusion
The current study evaluated the disposition of
Table 2a Pharmacokinetic parameters in HIV negative and HIV positive patients. Acute Pharmacokinetics of First Line Anti-tuberculosis Drugs in Patients with Pulmonary Tuberculosis 665 and in Patients with Pulmonary Tuberculosis Co-infected with HIV Table 2b Isoniazid pharmacokinetic parameters in HIV
mean age and mean CD4 lymphocytes count) of
negative and HIV positive patients.
patients involved in this study are similar to those of
patients who participated in the previous studies [12,
15–18]. Ethambutol Cmax, Tmax and half life found in
this study are similar to those reported in previous
studies and there is no significant difference between
HIV-negative and HIV-positive patients [12, 15–18].
The presence of HIV does not influence the disposition
of ethambutol. Isoniazid pharmacoki- netic parameters
found in this study and those reported previously [12,
15–18] are quite variable. This could be explained by
Table 2c Pyrazinamide pharmacokinetic parameters in
the differences between studies in the incidence of
HIV negative and HIV positive patients.
rapid and slow acetylators in the population. However,
(1500 mg HIV-negative HIV-positive significance
for each study, there is no significant difference
between pharmacokinetic values in HIV-negative and
HIV-positive patients. Our study does show a modest
Tmax (hrs) 2.5±0.26 2.4±0.43 0.084 37% reduction in AUC in HIV-positive patients. This
result is in variance with other studies and does indicate
the need for additional studies. The AUC that we report
in HIV-negative patients is very comparable to that
reported in normal health volunteers that are slow
acetylators . Whereas the AUC value we reported
Table 2d Rifampicin pharmacokinetic parameters in HIV negative and HIV positive patients.
in HIV-positive patients is between that reported for
rapid and slow acetylators of INH. The differences that
we report in INH AUC as a function of HIV status
could very well reflect differences in the number of
patients who are rapid acetylators between these
In this study, pyrazinamide and rifampicin Tmax,
1/2 and AUC values are higher than in studies
previously conducted [12, 15–18]. However, in each
ethambutol, pyrazinamide, isoniazid and rifampcin in
individual study, there is generally no significant
patients with active TB who were either HIV-positive
difference between HIV-negative and HIV-positive
or HIV-negative. The data suggests that isoniazid
patients. The most recent study from Botswana 
disposition is affected by HIV with the Tmax and
reported lower than expected concentrations of
AUC0-∞ being lower in patients co-infected with HIV.
pyrazinamide and showed that these were related to
The presence of HIV had no effect in this study on the
treatment outcomes. This study, however, showed only
disposition of ethambutol, pyrazinamide or rifampicin.
very modest influences (p < 0.04) of HIV infection on
Several studies have evaluated the influence of HIV on
the disposition pyrazinamide and rifampin. These
the pharmacokinetics of first line anti-TB drugs. The
results are not that much different that this study in
demographic parameters (number, gender balance,
666 Acute Pharmacokinetics of First Line Anti-tuberculosis Drugs in Patients with Pulmonary Tuberculosis and in Patients with Pulmonary Tuberculosis Co-infected with HIV
In HIV positive patients, renal function was mildly
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