Acute Oral Toxicity Evaluation of Andrographolide Self-Nanoemulsifying Drug Delivery System (SNEDDS) Formulation.

CONTEXT: Andrographolide (AND) is an active compound of well-known medicinal plant Andrographis paniculata. It has been widely published for various activities. AND is difficult to develop into dosage form due to its poor solubility and bioavailability. This problem could be solved by using self-nanoemulsifying drug delivery system (SNEDDS) for its formulation. However, the increase of bioavailability might result in potential toxicity as a large amount of drug is absorbed. AIMS: The aim of this study is to evaluate the acute potential toxicity using Organization for Economic Cooperation and Development (OECD) test: 401 methods. SUBJECTS AND METHODS: The OECD 401 method employs groups of animals treated by a single dose or repeated dose (<24 h) of the drug with three variances of doses. In this study, thirty male Wistar rats were divided into five groups which consisted two groups of control and three groups of AND SNEDDS formulation (500, 700, and 900 mg/kg body weight [BW], respectively). Intensive observation of toxicity symptom was performed during the first 30 minutes followed by periodic observation for 14 days. Posttermination, histopathological examination of the liver and kidney was conducted to confirm the toxicity symptoms. To determine the level of toxicity, the lethal dose 50 (LD50) value was calculated at the end of the study.
RESULTS: The result showed that all groups presented similar toxicological symptoms such as salivation, lethargy, and cornea reflex. However, based on histopathological examination, there were abnormalities, but still in an early stage. The toxicological symptom that emerged seems related to the SNEDDS formulation with lipophilic properties. Furthermore, the value of LD50 was 832.6 mg/kg BW (po).
CONCLUSIONS: The AND SNEDDS formulation was slightly toxic in male Wistar rats po. Copyright:

INTRODUCTION

One of the Indonesian medicinal plants, Andrographis paniculata Ness, which locally known as sambiloto has an active compound namely andrographolide (AND). Previous researches showed various activities of AND such as anti-influenza,[1] anti-dengue virus,[2] hepatoprotective,[3] anti-tumor,[4] anti-bacterial, anti-oxidant,[5] immunomodulatory,[6] anti-inflammation, analgesic,[7] anti-hyperlipidemia, and anti-diabetic.[8] In addition, it also reported for clinical application.[9]

AND is a diterpenoid compound characterized by its relatively lipophilic (log P = 2.632) and its solubility at 25°C is 3.29 μg/mL.[10] The oral bioavailability of AND was reported only for 2.67% with the dose 120 mg/kg body weight (BW) in rat (po).[11] Other research supported previous finding stated that isolated AND from sambiloto with the dose of 20 mg/kg BW, reduced its bioavailability four times lower after 10 times doses augmentation.[12] Those findings indicated that both solubility and bioavailability become burden for further research of AND. Hence, the formulation of AND into dosage form is expected to cover its laxity. A study of AND on nanoparticles formulation reported the improvement of bioavailability, target distribution, and efficacy.[1314]

Self-nanoemulsifying drug delivery systems (SNEDDS) are one of nanoparticle drug delivery system which contains the mixture of oil isotropic, surfactant, co-surfactant, and the drug (active compound). This drug design produces spontaneous nano-emulsion (self-emulsifying) when transferred into the water phase[14] such as the upper part of intestinal content.[15] The emulsion resulted from SNEDDS formulation has particle size around 50–500 nm, thermodynamically stable, and good dispersion between water and oil phase.[16] Moreover, other study showed that SNEDDS increased the oral bioavailability of lipophilic drug by 2.4 times comparing to the conventional formulation.[1317]

In parallel of increasing both bioavailability and solubility, it is resulting in the higher level of drug absorption that leads of potential toxicity. As one of nanoparticles drug design, SNEDDS may have similar toxicity feature as nanoparticles formulation does, such as inducing reactive oxygen species formation and free radical,[18] also accumulate within cells which lead cell damage.[19] Moreover, the materials that commonly used for SNEDDS formulation also reported some safety issue on separate studies. As oil vehicle, Capryol 90 was reported as mostly toxic compounds among propylene glycol ester group.[20] Meanwhile, Tween 20, a surfactant from the class of polysorbate appeared more toxic on cell line assay[21] and as co-surfactant, PEG-400 induced slight renal toxicity[22] and mucosal changes in the stomach.[23] With the emerged of toxicity from SNEDDS formulation,[24] this study is aimed to evaluate acute potential toxicity of AND SNEDDS formulation using Organization for Economic Cooperation and Development (OECD) 401 method.

SUBJECTS AND METHODS

Materials

The materials used in this study including isolated AND form A. paniculata (level of purity 95.74 ± 0.29%) was obtained from previous research.[25] Capryol-90, tween 20, and PEG 400 were bought from Brataco Indonesia Ltd for SNEDDS formulation. While, male Wistar rats attained from Preclinical laboratory, Department of Pharmacy, Universitas Islam Indonesia.

Andrographolide self-nanoemulsifying drug delivery system formulation and evaluation

AND SNEDDS formulations were prepared by adding 3 mL of Tween 20 into 15 mg AND and homogenized using ultrasonic homogenizer (model 300 V/T, USA). The mixture was then added by 1 mL of Capryol-90 and 1 mL of PEG 400 to reduce precipitation and homogenized for 15 min resulting clear colored formulation. The nano emulsion will be formed spontaneously when it diluted with water once it contacts the gastric juice (reconstitute with water). The evaluation of SNEDDS formulation consist of physical stability, determination of percent transmittance, particle size, polydispersity index (PDI) and zeta potential (surface charge). The evaluation of physical stability was carried out by thermodynamic method, stored at temperature between 2°C and 50°C, 8 h each stored for a minimum 48 h (3 cycles). Determination of particle size, PDI and zeta potential was analyzed using particle size analyzer (PSA) (Horiba SZ 100, Japan). The ANDS were 100-fold diluted with double distilled water.

Toxicity assay

The toxicity assay in this study using OECD 401 method which apply at least 3 variant of doses that comprise lethal or toxic dose on the animal (yielded from preliminary study). For this purpose, healthy male Wistar rats (8–12-week-old) with 200–250 g BW were employed to this study. The animals were placed in separate cage with room temperature (22°C–25°C, 55 ± 10% humidity), maintained on a 12 h day/night cycle, and free access to a normal rat diet along with water ad libitum. The ethical clearance was obtained from Ethical committee of Medical Faculty, Universitas Islam Indonesia (reference no. 11/Ka.Kom.Et/70/Ke/II/2018).

Thirty male Wistar rat divided into five groups, three groups were administrated by AND SNEDDS formulation (dose of AND: 500, 700, and 900 mg/kg BW respectively, based on preliminary study) and two control groups (normal and vehicle solution) per oral. With maximum volume of 2 mL each, the treatment was given in fraction over a period not exceeding 24 h. Following the treatment administration, all animal subjects were observed intensively for toxicity symptom during first 30 minutes (after each fraction of the treatment dispensed) and periodic (gradually every hour, 2 h, 4 h, 6 h, and 8 h) observation during 24 h for 14 days (daily observation for day 2–14). Toxicity symptom observation covered any abnormality of central nervous system and somatomotor activity (behaviour pattern, movement, sensitivity to stimuli), autonomic nervous system (salivation, lacrimation), respiratory (rate and characteristic of respiration), cardiovascular (heart rate pattern), gastrointestinal (feces consistency and colour), genitourinary (prolapse of the penis), skin and fur (colour and texture), mucosal membrane (mouth conjunctivitis), and general performance (such as BW). Termination of the animal study was performed at the 14th day posttreatment with overdose ketamine-xylazine and continued by organ isolation. Necropsy process also conducted on died animal studies during observation. Isolated organs (liver and kidney) were then proceed for histopathological examination.

RESULTS

The characterization of AND SNEDDS formulation resulted clear and transparent appearance, no phase separation and precipitation of drug in the emulsion based on visual assessment. Those results were supported by the level of percent transmittance as 99.8 ± 0.0015% which figured out the dispersion and transparency of the emulsion. Using PSA, the particle size of the formulation was obtained 12.1 ± 0.2 nm with PDI 0.327 ± 0.07 and zeta potential −37.8 ± 3.0 mV.

All animals study was observed for any behavioral changes, abnormality, toxic manifestation, and mortality up to 14 days. Almost entire AND SNEDDS-treated animals had similar toxicity symptoms which the most frequent sign were gasping, cornea reflex, lethargy and diarrhea. Higher concentration of the treatment, more frequent the symptom appeared. Furthermore, an hour post treatment, there were three animals died on each concentration of 700 and 900 mg/kg BW, but only one animal died on 500 mg/kg BW.

To determine the mortality cause of animal studies, histopathological evaluation was performed using hematoxylin eosin stain. Both liver and kidney of died animal during the study period and terminated animal (on the 14th day after treatment) were isolated for this purpose.

According to Figure 1b-e, hydropic and fatty degeneration (FD) were found on the liver. Hydropic degeneration (HD) or cellular swelling [Figure 1b-e] has been spotted in all groups except normal [Figure 1a]. As shown in Figure 1d and e, animal treated with AND SNEDDS formulation of 700 and 900 mg/kg BW demonstrated FD form of the liver. The liver FD characterized by the appearance of intra-cytoplasmic fatty vacuole. This alteration was prominent along with dose increased.

Figure 1

Histopathology of the liver. (a) Normal hepatocyte. (b) Self-nanoemulsifying drug delivery system vehicle-treated rat. (c) Andrographolide self-nanoemulsifying drug delivery system-treated rat dose 500 mg/kg body weight. (d) Andrographolide self-nanoemulsifying drug delivery system-treated rat dose 700 mg/kg body weight. (e) Andrographolide self-nanoemulsifying drug delivery system-treated rat dose 900 mg/kg BW. FD: Fatty degeneration; HD: Hydropic degenerations

Meanwhile, protein accumulation (PA) in glomerular tubule displayed in all AND SNEDDS-treated rat [Figure 2c-e] and vehicle group [Figure 2b] that indicated glomerulonephritis. Another kidney pathology found was acute tubular necrosis (ATN) on AND SNEDDS-treated rat dose 700 and 900 mg/kg BW [Figure 2d and e]. It commonly found in toxic event that alter sodium gradient concentration of kidney causing swelling of the cell to focal tubular necrosis and apoptosis. Interestingly, it only featured in one rat among others in each group AND SNEDDS formulation of 700 and 900 mg/kg BW.

Figure 2

Histopathology of the kidneys. (a) Normal kidney. (b) Self-nanoemulsifying drug delivery system vehicle-treated rat. (c) Andrographolide self-nanoemulsifying drug delivery system-treated rat dose 500 mg/kg body weight. (d) Andrographolide self-nanoemulsifying drug delivery system-treated rat dose 700 mg/kg body weight. (e) Andrographolide self-nanoemulsifying drug delivery system-treated rat dose 900 mg/kg body weight. PA: Protein accumulation; ATN: Acute tubular necrosis

To determine of the toxicity level, lethal dose 50 (LD50) was counted using the data of animal mortality using Thompson and Weil formula.[26] With the formula of LD50 = log D + d (f+1), giving the result of LD50 for AND SNEDDS was 832.6 mg/kg BW (po). The value of D is the minimum dose causing death (500 mg/kg BW), d is the logarithm of the constant ratio between dosage level (log 1.35 in this regard) and f is the value from the table of Weil based on the number animal death for each Group (0, 1, 3, 3). In addition, according to Hodge and Sterner toxicity scale, the obtained value of LD50 between 500 and 5000 mg/kg classified that AND SNEDDS formulation was slightly toxic.

DISCUSSION

The OECD is a testing method that internationally accepted for evaluating the safety of chemicals. Using this method, it allows to employ the small number of animal study. The OECD 401 is one of the techniques to assess acute toxicity through observation of toxicity symptoms and determination of IC50 level. Developing AND into SNEDDS formulation augment the toxicity risks which need to be evaluated on its acute toxicity level.

Based on the results, it was found that toxicity symptoms appeared posttreatment of AND SNEDDS formulation and worsened as dose increasing. Furthermore, the symptoms also persisted more than 24 h after intensive and periodic observation. This finding suggested that AND SNEDDS formulation might be related to toxicity event. To determine the toxicity occurrence, histopathological examination of the liver and kidney was conducted.

Liver FD is one of metabolism abnormality of the cell that induces the disruption of cell function as well as its structure. This reversible form is characterized by metabolic product abnormal amount such as lipid, protein, and glycogen (shown with letter FD). In severe condition, lipid accumulates in the hepatocytes as vacuole which has clear appearance with hematoxylin and eosin staining and exerts the nucleus towards the edge.[27] Even though fatty change occurs on all treatment groups, the alteration is still in early stage (simple steatosis) that may cause by poisoning substance. This may result from fatty food intake to the animals during the study.[2829] although in this study all animals fed by standard pellet.

Other liver abnormality found in this study was HD or vacuolization of the hepatocyte's cytoplasm [Figure 1c-e]. It is defined as an acute reversible change resulting as response nonlethal injuries and characterized by intracytoplasmic accumulation of water. It is a result of ion and fluid homeostasis that lead to an increase of intracellular water.[30] Furthermore, it might indicate acute liver injury induced by AND SNEDDS.[31] In this study, vehicle solution-treated group has similar histology appearance of HD that indicates the abnormality did not correlate on AND addition. The possible factor causing cellular swelling was the formulation of the SNEDDS.

Along with many advantages, SNEDDS formulations have limitation on lower drug concentration. Amount of AND that can be inserted into SNEDDS formulation was only 15 mg/mL, which was then the administration must be delivered in small fraction repeatedly for 24 h to achieve targeted dose. Macroscopic findings of lumen tubular and stomach of AND SNEDDS-treated rat support previous statement. Organ swelling was found due to imbalance between absorption rate and water intake which occurs in animal died 60 min after treatment. However, no significant differences between animal died during the study and sacrificed animal on histopathological results.

In accordance to kidney evaluation, acute glomerulonephritis marked by PA was figured out. Acute glomerulonephritis can be caused by toxic component disrupting glomerular capillary followed by glomerular edema. This histology feature was not only captured in 900 mg/kg BW, but also in all treatment group [Figure 2c-e] and vehicle solution control group [Figure 2b] compared to the normal group [Figure 2a]. The differences among them were the amount of accumulated protein in parallel with the concentration.

ATN also displayed in some animal study in dose 700 and 900 mg/kg BW. ATN induce the decreasing of glomerular filtration rate (GFR) and caused by acute ischemic or toxic event that led hypoperfusion. Cast and debris that obstructing tubule lumen may also contribute in this phenomenon.[32] Based on clinical pattern, early stage of ATN characterized by the lower rate of GFR and sudden elevating of serum creatinine and concentration of BUN. In order to maintain cellular integrity and renal function, cellular repair and proliferation perform in maintenance and recovery phase.[31] In this study, ATN was associated with high volume administration of SNEDDS formulation that possibly causing the configuration of cast and debris which impede tubule lumen of kidney. Moreover, the lipophilic property of SNEDDS formula will be passively absorbed inside tubular cells and stay in lumen tubular. Delayed absorption induces animal death due to exhausted effect.

Hence, the histology observation of the kidney supported the histology figure of the liver. Rather than the AND as the main active compound, the SNEDDS formulation that may raise potential toxicity. Previous acute oral toxicity studies on standardized AND extract did not found any treatment-related toxic effect in the rat with upper fixed dose 5000 mg/kg BW.[3334] Furthermore, in pure compound, AND also reported did not exert significant toxicity sign both in acute and subacute studies.[35] Meanwhile, AND in SEDS formulation featured higher cytotoxic potential than in the extract[36] which verified that the formulation alter the toxicity profile.

In this recent study, SNEDDS formulation had nanoparticle size less than 100 nm and good dispersion parameter (PDI < 0.7) indicated homogeneity of particle size that may elevate cell uptake[37] of the drug by enhancing the total surface area.[1338] More chemical molecule may attach to the surface affected on its reactivity and increasing its toxic effect. Those result was supporting previous findings that AND nanoparticle was transferred across blood brain barrier[39] and largely distributed in the liver[40] due to its tiny particle size. Nano particle size has been demonstrated exhibit concentration-dependent toxicity that induced cytotoxicity, inflammation, and genotoxicity thus modify metabolic activity and promote membrane damage.[41]

Other factors that must be considered in this study was smaller amount of active compound that can be loaded in the SNEDDS formulation, produce large volume to be administered during 24-h. That reason also impacted on narrow concentration of the drug is possible to investigate and increasing the risk of animal died by high volume ingested instead of illustrating the toxicity of drug treated. Reformulation of the SNEDDS that may enable to increase the drug concentration and reduce volume of administration is preferable.

CONCLUSIONS

The AND SNEDDS formulation was slightly toxic in male Wistar rats per oral with the level of LD50 was 832.6 mg/kg BW.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.