INTRODUCTION:

According to WHO statistics, it is found that around 37.9 million people in the world were suffering from HIV. In 2018, approximately 37.9 million people were infected with HIV resulting in a death rate of around 770000. In 2018, around 1.7 million new HIV cases were observed as compared to 2017¹. AIDS is a chronic disease that occurs due to the Human immunodeficiency virus (HIV), which causes irreversible destruction of the immune system².

A combination of antiretrovirals therapy is administered for the prevention of AIDS³. Non-nucleoside reverse transcriptase inhibitors (NNRTIs) noncompetitively inhibit the reverse transcriptase enzyme which transcribes the single-stranded HIV-1 RNA into DNA which ultimately blocks the replication of HIV-1 in the host^4,5.

Efavirenz belongs to the category of nonnucleoside reverse transcriptase inhibitor⁶. It is used as a first-line antiretroviral drug in the high activity antiretroviral therapy (HAART) for treating the infection caused by the human immunodeficiency virus (HIV)⁷. Efavirenz comes in the BCS class II category has high lipophilicity with Pka10.2 and 4.6 log𝑝 value having low water solubility (<10µg/ml)^8,9,10. Due to low water solubility of the drug, low bioavailability (40–45%), and high intrasubject variability of the drug are observed which results in high first-pass metabolism^11,12. Tablet (600mg) or Capsules (50mg or 200mg) were the available dosage form of this drug¹⁰. Its half-life is about (40–55 h after repeated dosing)¹³ leading to a long-lasting reduction in HIV RNA after once-a-day dosing (600 mg)¹⁴. Efavirenz alters the conversion of viral RNA to DNA by blocking the reverse transcriptase enzyme. Efavirenz is given in combination therapy for the treatment of HIV-1/AIDS. Currently, there is an enormous approach for using SLN as a carrier in the anti-HIV drug delivery^15,16.

In the last 10 years, Lipid nanoparticles have gained more attention as a promising strategy which avoids the drawbacks as well as combines the advantages of colloidal drug carrier systems such as liposomes, polymeric nanoparticles, and emulsions like increases the protection of drug against enzymatic metabolism improves the drug stability, ease of large-scale production and sterilization, less variability in release mechanisms and their kinetics¹⁷. The physiochemical diversity and biocompatibility of lipids and their capacity to enhance oral bioavailability of drugs have a high influence on lipid nanoparticles for oral drug delivery. Moreover, lipid nanoparticles having a solid matrix showed high drug loading (both hydrophilic and lipophilic drugs)^18,19.

Lipid nanoparticles with a solid matrix referred to as Solid lipid nanoparticles were introduced as the ﬁrst generation of lipid nanoparticles²⁰.

The solid lipid nanoparticles (SLN) are at the forefront of the rapidly developing field of nanotechnology as submicron carriers ranging 50–1000nm in size. It is composed of biocompatible and biodegradable solid lipid as a solid core, coated with non-hazardous surfactant/cosurfactant as the outer shell²¹. It is having the ability to incorporate both lipophilic and hydrophilic drugs²².

In SLNs, the solid matrix of the lipids shows high flexibility in controlling the drug release and also protects the encapsulated drugs from gastric degradation. By using solid lipids, drug absorption is increased mainly through enhanced drug dissolution and solubilization in the intestinal-milieu improved lymphatic-transport enhanced gastrointestinal permeability and decreased gastric-emptying rate^23,24.

In this research work, an attempt was made to design and develop solid lipid nanoparticles of efavirenz, an anti-HIV drug to increase their solubility and bioavailability after oral administration along with overcoming the drawbacks which are associated with the drug such as low oral bioavailability due to first-pass metabolism, low solubility, high protein binding.

MATERIALS AND METHOD:

Materials:

Efavirenz was procured as a gift sample from Ami life science Vadodara, Gujarat, India. Glyceryl monostearate, Potassium dihydrogen phosphate, Distilled water, Diethylene glycol mono ethyl ether were purchased from Central drug house (P) Ltd., New Delhi, India. Ethanol was acquired from Merck, India. Tween80 was purchased from Thomas Baker (Chemicals) Pvt. Limited, Mumbai, India. Methanol, Sodium hydroxide was obtained from SD Fine Chem Limited, Mumbai, India.

Methods:

Selection of lipid:

The selection of lipids for the formulation of SLN was based upon the maximum solubility of the drug in the lipid. The solubility of the drug was screened in different lipids such as Glyceryl monostearate, decanoic acid, tripalmitin, stearic acid. The drug was dissolved in a known amount of each lipid at a temperature 5^○C above the melting point of the respective lipid using a water bath (HICON, Uttar Pradesh, India). Continuous addition of drug is done, till a clear pale solution was obtained. Then the lipid which is having maximum solubility for the drug indicates the maximum loading capacity of drugs and is used for further examination²⁵.

Drug-Excipients Interaction Study:

Firstly, the IR spectra of the drug (Efavirenz) was scanned then drug, glyceryl monostearate, tween 80, and cosurfactant were taken in a ratio of 1:1 into a pallet which was kept on to the sample holder and determined through FT-IR Spectrophotometer(Perkin-Elmer Pvt. Ltd, UK). The sample was scanned within the wavenumber range between 4000cm- to 650cm- for recording the spectra^26,27.

Preparation of Efavirenz loaded solid lipid nanoparticle:

Efavirenz loaded Solid lipid nanoparticle was prepared through the microemulsion method followed by lyophilization technique. In this process, a lipid phase was prepared by melting 1gm of glyceryl monostearate at 70^○C and mixed with 200mg of drug-using vortex shaker (Khera laboratory (P) Ltd, New Delhi, India). An aqueous phase contains 1ml of tween 80 mixed with the cosurfactant solution (1.5ml Diethylene glycol mono ethyl ether and 1.5ml ethanol) using a vortex shaker and heated at the same temperature as the lipid phase. Then an aqueous phase was added to the lipid phase dropwise with continuous agitation using a vortex shaker. Then warm water was added dropwise to sample solution with continuous agitation till a clear solution was formed through the vortex shaker then a warm microemulsion was formed. After this, warm microemulsion was transferred dropwise to 10ml cold water (0-2^○C) with a needle through a magnetic stirrer(Navyug Laboratory Ltd, Gujarat, India) then a microemulsion solution was formed. This sample solution was lyophilized for 36 hr at a temperature of -90^○C through lyophilizer(Multitech lab Instruments, Chennai, India) leading to the formation of SLN powder^28,29.

Characterization:

Shape and Surface Morphology:

The Shape and surface morphology of the lyophilized SLN was visualized by scanning electron microscopy (SEM; Field Emission Electron Microscope, MIRA 3LMH Tescan). Lyophilized SLN sample was placed onto carbon stubs through double-sided carbon adhesive tape and then coated with gold of 10nm in a high-vacuum evaporator under an argon atmosphere. The sample analysis was randomly scanned at different magnifications and the voltage was set at 10 kV³⁰.

Differential Scanning Calorimetry:

Thermal analysis was carried out using (SDT Q600 V20.9 Build 20) with Q Series-[Q600-1211- SDT Q600@mfg-sdt] software. The Lyophilized sample was weighed 4.3205mg and placed on an aluminium pan which was scanned at 0°C up to 250°C range of temperature with a heating rate of 10°C/min purged with nitrogen at a flow rate of 99.96mL/min.

Powder X-Ray Diffraction (PXRD) analysis:

The Diffraction patterns of freeze-dried SLNs were recorded using an XꞌPERT³ diffractometer system (PANalytical, The Netherlands). Lyophilized SLNs sample was placed in a glass sample holder where copper was used as anode tube (Cu Kα1, λ =1.540598 Å ) and (Cu Kα2, λ =1.544426 Å) with a fixed divergence slit of 0.871mm. The analysis was carried out in the range of 2θ with a voltage of 45 kV, a current intensity of 40 mA. The scanning was performed in a continuous mode with a step size of 0.02°³¹.

Drug Entrapment Efficiency:

Entrapment efficiency was measured by using 50 mg of the lyophilized solid lipid nanoparticle dispersed in 10mL (methanol+0.2M phosphate buffer PH7.4) of ratio 1:9 then centrifuged (Remi Motors Ltd, Mumbai, India) at 5000rpm for 30 min. The supernatant liquid was isolated and the amount of free drug was analysed at 245nm in UV Spectrophotometer (Shimadzu Analytical Pvt. Ltd, Mumbai, India). The equation used to measure the EE% given below^32,33.

Actual loading

Entrapment efficiency % = ----------------------- × 100

Theoretical loading

Total drug − Free drug

Actual loading (%) = ------------------------------- × 100

mg of lyophilized powder

Total drug

Theoretical loading (%) = ------------------------- × 100

Total drug + Total excipient

In Vitro Drug Release Study:

The in-vitro drug release profile of lyophilized EFV-SLN and marketed formulation (Efavir) capsule was investigated using dissolution apparatus(Vinsyst technologies) operated at 50rpm and 37^◦C. Lyophilized formulation (equivalent to 200mg of EFV) filled in capsule shell was added into 250ml dissolution medium (PBS (pH 7.4) and methanol solution) in a ratio of (9:1) for maintaining the sink conditions. At a particular time interval, 5ml of the sample solution was withdrawn from the dissolution medium and then an equivalent volume of fresh dissolution medium was added. The entire release studies were conducted in triplicate and monitored through UV Visible spectrophotometer at 245nm^34,35.

In vitro drug release Kinetic models:

The kinetics of efavirenz release from SLN was analysed through different release kinetic models such as zero order release kinetics, first-order release kinetics, Higuchi model, Hixson-Crowell model, and Korsmeyer–Peppas model³⁶.

Stability Assessment:

The stability of the lyophilized EFV-SLN formulation was assessed according to ICH guidelines under different storage conditions. The lyophilized efavirenz loaded solid lipid nanoparticles formulation was placed at 45°C with a relative humidity of 75% for 3months to evaluate the physical stability. The lyophilized sample was taken at 0 days, 1 month, 2 months, 3 months, and during this period, the degradation rate, and the shelf life of lyophilized EFV-SLN were analysed^37,38.

RESULTS AND DISCUSSION:

Selection of lipid:

GMS is used as a lipid because the solubilizing potential of the GMS for this drug is higher in comparison with other lipids. It can accommodate a higher amount of drugs in less quantity of lipids.

Drug and excipient compatibility study:

FT-IR spectroscopy was used to evaluate the interaction between the drugs with the excipient in the sample. A separate IR spectrum of Efavirenz was run as showed in (fig.1) and represented in (Table1) and then a physical mixture of Efavirenz with glyceryl monostearate, tween 80, and cosurfactant was compared to identify the presence of the additional peak which occurs due to drug excipient interaction. Based on observation of the spectra in (fig.2,3,4,5) no drug excipient interaction occurs which determines that drug and excipient were compatible with each other.

Fig.1: FT-IR spectra of EFV using the neat analysis method.

Table 1: Functional group present in EFV.

S. no	Functional groups	Range (cm^-1)	Peak (cm^-1)
1.	-C-H	600-1500	1041
2.	-C≡H	2100-2660	2247
3.	R-C-OṘ ║ O	1680-1760	1746
4.	R-N-Ṙ │ H	1180-1360	1188

Fig.2: FT-IR spectra of glyceryl monostearate.

Fig.3: FT-IR spectra of tween 80.

Fig.4: FT-IR spectra of EFV-SLN.

Fig.5: FT-IR spectra of a) Drug b)EFV-SLN.

Shape and Surface Morphology:

Scanning electron microscopy (SEM) analysis confirmed the lyophilized SLN sample appeared spherical and irregular shape with a smooth surface as shown in (fig.6).

Fig.6: SEM micrograph of lyophilized SLN(5µm).

Differential Scanning Calorimetry:

The DSC thermogram of pure drug EFV indicated a sharp endothermic peak at 138^oC which was matching with the melting point of pure EFV determines the purity of efavirenz as shown in (fig.7). The DSC thermogram of lyophilized EFV-loaded SLN showed the presence of a single sharp endothermic peak at 57.15^◦C as shown in (fig.8). Therefore, DSC analysis reported the absence of a peak for Efavirenz which showed the appearance of a single polymorphic form of the solid lipid due to efavirenz was molecularly dispersed in the solid lipid nanoparticle matrix.

Fig 7: DSC thermogram of pure drug efavirenz³⁹.

Fig 8: DSC thermogram of lyophilized efavirenz loaded solid lipid nanoparticle.

Powder X-Ray Diffraction (PXRD) analysis:

The nature of lyophilized efavirenz loaded SLN was determined using X-ray diffraction studies. Pure efavirenz presented multiple diffraction peaks which confirms the crystalline nature of the drug as shown in (fig.9). The two sharp peaks were obtained in lyophilized efavirenz loaded SLN at 21.7^○ and 24.3^○as shown in (fig.10). It is observed that no new peaks are found on comparing the diffractogram of pure EFV and lyophilized efavirenz loaded SLN there is a similarity in peaks. Therefore, it is suggested that EFV was in a molecularly dispersed form in the SLN formulation.

Fig.9: X-ray diffractogram of pure drug efavirenz⁴⁰.

Fig.10: X-ray diffractogram of lyophilized efavirenz loaded SLN.

Drug Entrapment Efficiency:

The %EE of the lyophilized EFV-SLN formulation was 60.41% prepared through microemulsion technique whereas the drug loading was found to be 7.68%.

In Vitro Drug Release Study:

The In-vitro drug release profile of lyophilized efavirenz loaded solid lipid nanoparticle was assessed through the dissolution apparatus and was compared with the drug release profile of the marketed product (Efavir). Lyophilized efavirenz loaded solid lipid nanoparticles showed a drug release of 88.2% whereas Efavir showed a drug release of 54.95% as shown in a (table 2). It was observed that drug release from SLN was found to be more consistent as compared to the release of drug from Efavir as shown in (fig.11). The results obtained from dissolution data it was found that the dissolution rate of the poorly water-soluble drug can be improved through the formation of solid lipid nanoparticles.

Table 2: In-vitro drug release study profile of EFV-SLN and Efavir (Each value represents mean n=3, ±S.D).

Formulation	% Drug release
EFV-SLN	88.2±0.12
Efavir	54.95±0.14

Fig.11: A graph of in-vitro drug release profile of EFV-SLN and Efavir.

Release Kinetic model in SLN:

The drug release profile of EFV-SLN and Efavir obtained was fitted into different kinetic models as represented in the table. EFV-SLN formulations followed the first-order release model as its r² is 0.9895 and follows non-fickian diffusion which was compared with the marketed formulation (Efavir) follows the first-order release model as its r² is 0.9653 and follows non-fickian diffusion. The results shown in (table 3) indicate that the drug release profile of EFV-SLN was better as compared to the marketed formulation (Efavir) and fitted best in the first-order release model which confirms that the release of drug is concentration-dependent.

Stability Assessment:

3-month stability study of the lyophilized efavirenz loaded solid lipid nanoparticles formulation determined no significant change in the physical appearance at 45°C and 75% for 3months indicating the stability of the formulation. The degradation rate of lyophilized EFV-SLN formulation followed first-order kinetics and ranges between 2% after 3month as shown in (Fig.12) It was determined that shelf life (𝑡90) of the lyophilized EFV-SLN formulations was found to be 150 days. It was experimentally done in triplicate (n=3, ±S.D).

Fig 12: Stability study data of the lyophilized EFV-SLN based on degradation rate at 45°C.

CONCLUSION:

The present research work determined that efavirenz loaded solid lipid nanoparticles were successfully formulated using GMS as lipid through the microemulsion method followed by the lyophilization technique. The in-vitro release data demonstrate that the drug release of EFV-SLN was better as compared with the marketed formulation and the drug release is concentration-dependent. The formulation would provide stability at room temperature. This study showed that SLN would be a promising lipid carrier for oral administration which improves oral delivery of poorly water-soluble drug-like Efavirenz with increased solubility which in turn potentially enhanced bioavailability. In future perspectives, the produced EFV-loaded SLNs have the potential to be scaled up for commercial production, and a simple instrument is required during preparation. This SLN formulation would have better therapeutic efficiency which decreased dosing and have lesser side effects. It is concluded that SLN is a potential lipid nanocarrier to treat HIV.

ACKNOWLEDGEMENT:

The authors are grateful to the authorities of Pranveer Singh Institute of Technology, Kanpur for the facilities.

CONFLICT OF INTEREST:

The authors declare no conflict of interest.

REFERENCES:

1. UNAIDS. Global HIV and AIDS statistics- 2019 fact sheet. Available from: URL:https://www.unaids.org/en/resources/fact-sheet (Accessed 2017).

2. Duzgunes N, et al. Delivery of antiviral agents in liposomes. Methods in Enzymology. 2005; 391:351-73.

3. Clercq ED. Anti-HIV drugs: 25 compounds approved within 25 years after the discovery of HIV. International Journal of Antimicrobial Agents. 2009; 33:307–320.

4. Gupta U and Jain NK. Non-polymeric nanocarriers in HIV/AIDS drug delivery and targeting. Advanced Drug Delivery Reviews. 2010; 62:478–490.

5. Sosnik A, Chiappetta DA and Carcaboso AM. Drug delivery in HIV pharmacotherapy: what has been done and the challenges standing ahead. Journal of Controlled Release. 2009;138:2–15.

6. KhanMY, et al.^. Formulation and Evaluation of Efavirenz 600 mg Tablet. Asian Journal of Research in Pharmaceutical Science. 2015; 5(3):153-167.

7. Vidyadhara S, et al. Simultaneous UV Spectrophotometric Method for the Determination of Tenofovir, Efavirenz and Lamivudine in Bulk and Combined Dosage Form. Asian Journal of Pharmaceutical Analysis. 2016; 6(4):253-258.

8. Rabel SR, Maurin MB, Rowe SM and Hussain M. Determination of the pKa and pH-solubility behavior of an ionizable cyclic carbamate, (S)-6-chloro-4-(cyclopropylethynyl)-1,4-dihydro-4-(trifluoromethyl)-2H-3,1-benzoxazin-2-one(DMP 266). Pharmaceutical Development and Technology. 1996; 1:91–95.

9. DrugBank. Efavirenz. Available from: URL: https://www.drugbank.ca/drugs/DB00625 (Accessed June 13, 2005).

10. Sustiva® Prescribing Information. Bristol-Myers Squibb Company. Available from: URL:http://www.sustiva.com (Accessed October, 2017).

11. Chiappetta DA, Hocht C, Taira C and Sosnik A. Oral pharmacokinetics of the anti-HIV efavirenz encapsulated within polymeric micelles. Biomaterials. 2011; 32:2379–2387.

12. Mistry A, Stolnik S and Illum L. Nanoparticles for direct nose-to-brain delivery of drugs. International Journal of Pharmaceutics. 2009; 379:146–157.

13. Smith PF, DiCenzo R and Morse GD. Clinical pharmacokinetics of non-nucleoside reverse transcriptase inhibitors. Clinical Pharmacokinetic. 2001; 40:893–905.

14. Staszewski S, et al. Efavirenz plus zidovudine and lamivudine, efavirenz plus indinavir and indinavir plus zidovudine and lamivudine in the treatment of HIV-1 infection in adults. The New England Journal of Medicine. 1999; 341:1865–1873.

15. Wong HL, Wu XY and Bendayan R. Nanotechnological advances for the delivery of CNS therapeutics. Advanced Drug Delivery Reviews. 2012; 64:686–700.

16. Mallipeddi R and Rohan LC. Progress in antiretroviral drug delivery using nanotechnology. International Journal of Nanomedicine. 2010; 5:533–547.

17. Vakhariya RR, et al. Formulation Development and Optimization of Simvastatin Loaded Solid Lipid Nanoparticles. Asian J. Res. Pharm. Sci. 2017; 7(1): 49-52.

18. BhairavBA, BachhavJA, SaudagarRB. Review on Solubility Enhancement Techniques. Asian J. Pharm. Res. 2016; 6(3): 147-152.

19. Fundaro A, et al. Non-stealth and stealth solid lipid nanoparticles (SLN) carrying doxorubicin: pharmacokinetics and tissue distribution after i.v. administration to rats. Pharmacological Research. 2000; 42:337-43.

20. Iqbal MA, et al. Nanostructured lipid carrier’s system: recent advances in drug delivery. Journal of Drug Targeting. 2012; 20:813–830.

21. Mehnert W and Mader K. Solid lipid nanoparticles: production, characterization and applications. Advanced Drug Delivery Reviews. 2001; 47:165–196.

22. WakePS, Kshirsagar MD. Design and Characterization of Solid Lipid Nanoparticle Based Transdermal Drug Delivery System. Asian J. Res. Pharm. Sci. 2017; 7(2): 87-91.

23. Shah R, Eldridge D, Palombo E and Harding I. Optimisation and stability assessment of solid lipid nanoparticles using particle size and zeta potential. Journal of Physical Science. 2014; 25:59–75.

24. Ebrahimi HA, Javadzadeh Y, Hamidi M and Jalali MB. Repaglinide-loaded solid lipid nanoparticles: effect of using different surfactants/stabilizers on physicochemical properties of nanoparticles. DARU Journal of Pharmaceutical Sciences. 2015; 23:1-46.

25. Blasi P, et al. Solid lipid nanoparticles for targeted brain drug delivery. Advanced Drug Delivery Reviews. 2009; 59:454–477.

26. KhairnarDA, et al. A Review on Self- Micro Emulsifying Drug Delivery System: Evident to improve the oral bioavailability of hydrophobic drugs. Asian J. Pharm. Tech. 2016; 6(2): 131-134.

27. Indian Pharmacopoeia. Government of India Ministry of Health and Family Welfare. The Indian Pharmacopoeia Commission, Ghaziabad. 2014.

28. Kalaycioglu GD and Aydogan N. Preparation and investigation of solid lipid nanoparticles for drug delivery. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2016; 510:77-86.

29. Ashok P, et al. Irbesartan Formulation and Evaluation of Loaded Solid Lipid Nanoparticles by Microemulsion Techinque. Asian J. Pharm. Tech. 2020; 10(4):228-230.

30. Gaur PK, Mishra S, Bajpai M and Mishra A. Enhanced Oral Bioavailability of Efavirenz by Solid Lipid Nanoparticles: In Vitro Drug Release and Pharmacokinetics Studies. BioMed Research International. 2014;1:1-9.

31. Zaini E, Wahyu D, Octavia MD and Fitriani L. Influence of Milling Process on Efavirenz Solubility. Journal of Pharmacy and Bioallied Sciences. 2017; 9:22-25.

32. Katara R and Majumdar DK. Eudragit RL 100-based nanoparticulate system of aceclofenac for ocular delivery. Colloids and Surfaces B: Biointerfaces. 2013;103: 455–462.

33. Bisen A, Jain AP, Jain S. Formulation and Evaluation of Zidovudine Loaded Microsphere. Asian J. Res. Pharm. Sci. 2013; 3(4):200-205.

34. Youshia J, Kamel AO, Shamy AE and Mansour S. Design of cationic nanostructured heterolipid matrices for ocular delivery of methazolamide. International Journal of Nanomedicine. 2012; 7:2483–2496.

35. KulkarniSB, et al. Formulation and Evaluation of Immediate Release Tablet of Efavirenz by Micellar Solubilization Technique. Asian J. Pharm. Res. 2019; 9(1): 12-18.

36. Das S, Suresh PK and Desmukh R. Design of Eudragit RL 100 nanoparticles by nanoprecipitation method for ocular drug delivery. Nanomedicine: Nanotechnology, Biology, and Medicine. 2010; 6:318–323.

37. Khare A, Singh I, Pawar P and Grover K. Design and Evaluation of Voriconazole Loaded Solid Lipid Nanoparticles for Ophthalmic Application. Journal of Drug Delivery. 2016;1:1-11.

38. RasheedN, et al. Simultaneous Formulation Development, Evaluation and Estimation of Innovative Controlled Release Tablets of Bosentan Formulated with Varied Polymers. Asian J. Pharm. Ana. 2016; 6(4): 235-245.

39. Sruthi S, Kaparthi S, Babu PRS and Subrahmanyam CVS. Formulation and in-vitro evaluation of efavirenz liquisolid compacts. International Journal of Pharmacy and Pharmaceutical Science. 2016; 8(1):137-143.

40. Pokharkar V, Patil-Gadhe A and Palla P. Efavirenz loaded nanostructured lipid carrier engineered for brain targeting through intranasal route: In-vivo pharmacokinetic and toxicity study. Biomedicine and Pharmacotherapy. 2017; 94(1):150–164.

Received on 01.12.2020 Modified on 28.03.2021

Research J. Pharm.and Tech 2022; 15(3):1162-1168.

DOI: 10.52711/0974-360X.2022.00195

Formulation	Zero-order	First-order	Higuchi	Hixson-Crowell	Korsmeyer-Peppas
Formulation	r²	r²	r²	r²	r²	n	Diffusion
EFV-SLN	0.9017	0.9895	0.9597	0.9683	0.9704	0.7715	Non-fickian
Efavir	0.9319	0.9653	0.9521	0.9401	0.9617	0.5418	Non-fickian