A Novel Hydrophilic Adhesive Matrix with Self-Enhancement for Drug Percutaneous Permeation Through Rat Skin

Purpose  In transdermal drug delivery system (TDDS), chemical enhancers and crystallization inhibitors added into the adhesive matrixes to improve drug permeation and formulation stability often result in some negative effect on adhesive properties and dressing performance. The aim of this paper is to develop a hydrophilic pressure sensitive adhesive (PSA) for TDDS without using additional chemical enhancers and crystallization inhibitors. Methods  A quaternary blend (PDGW) composed of polyvinyl pyrrolidone, D,L-lactic acid oligomers, glycerol and water was prepared. The adhesive strength, drug loading capacity, drug state and stability of PDGW were characterized by using ibuprofen (IBU) and salicylic acid (SA) as model drugs. Moreover, In vitro and in vivo drug permeation through rat skin from PDGW patch in comparison to acrylate adhesive (ACA) and nature rubber adhesive (NRA) was investigated. Results  PDGW performs excellent drug loading and crystallization inhibition capacity. Furthermore, the accumulative amount for 24 h in vitro from PDGW patch is far higher than that from ACA and NRA patch. And the plasma concentration of drugs in vivo from PDGW patch is bigger than that from ACA patch. Conclusions  PDGW possesses excellent PSA properties and self-enhancement for drug percutaneous permeation, which can be used to develop new formulation of TDDS. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Comparative single-dose pharmacokinetics of rasagiline in minipigs after oral dosing or transdermal administration via a newly developed patch

Abstract

1. A rasagiline transdermal patch was developed for the treatment of early and advanced Parkinson’s disease. Relevant pharmacokinetic parameters of rasagiline obtained after transdermal administration to minipigs were compared with those of rasagiline after oral administration.

2. A total of 18 minipigs were randomly divided into three groups (six animals for each group). A single dose of 1?mg rasagiline tablet was orally administrated to one group. Meanwhile, single dose of 1.25 and 2.5?mg (2 and 4?cm²) rasagiline patches were given (at the postauricular skin) to the other two groups, respectively. The pharmacokinetic parameters such as plasma half-life (t_1/2), time to peak plasma-concentration (T_max), mean residence time (MRT), area under the curve (AUC_(0–t)) were significantly (p?<?0.05) different between transdermal and oral administrations.

3. The plasma half-life (t_1/2) of rasagiline (1.25?mg patch: 11.8?±?6.5?h, 2.5?mg patch: 12.5?±?4.7?h) in minipig following transdermal administration was significantly prolonged as compared with that following the oral administration (1?mg tablet: 4.7?±?2.5?h). The dose-normalized relative bioavailability of rasagiline patch in minipig were 178.5% and 156.4%, respectively, for 1.25 and 2.5?mg patches compared with 1?mg rasagiline tablet. The prolonged t_1/2 and increased bioavailability of rasagiline patch suggested a possible longer dosing interval compared with oral tablet.     

Rivastigmine exposure provided by a transdermal patch versus capsules

ABSTRACT

Objectives: The rivastigmine transdermal patch is the first transdermal treatment for Alzheimer's disease (AD) and dementia associated with Parkinson's disease. The objective of this study was to evaluate the pharmacokinetics of rivastigmine following transdermal delivery by a patch versus oral delivery with conventional capsules in a population of AD patients.

Methods: Both non-compartmental and compartmental analyses were performed on the same database showing relatively large inter-patient variations in pharmacokinetic parameters (up to 73% for the capsule group). The compartmental analysis provided model-based predictions of pharmacokinetic parameters, with the aim of comparing the two modes of administration when adjusting for confounding factors such as patient body weight and gender.

Results: According to both non-compartmental and compartmental analyses, the patch provided significantly lower peak rivastigmine plasma concentrations (C_max) and slower times to C_max (t_max), compared with capsules. However, drug exposure (area under the curve; AUC) was not significantly different between the 4.6?mg/24 hour (5?cm²) patch and 3?mg BID (6?mg/day) capsule doses, or between the 9.5?mg/24 hour (10?cm²) patch and 6?mg BID (12?mg/day) capsule doses, according to both analyses. This suggests comparable exposure from these two rivastigmine delivery systems.

Conclusion: The analyses were consistent with previous reports of a markedly less fluctuating, more continuous drug delivery with the rivastigmine patch. This characteristic delivery profile is associated with similar efficacy yet improved tolerability, compared with capsules.     

口服布洛芬原位凝胶的制备及其在Beagle犬体内药代动力学研究

本文设计并制备了口服布洛芬原位凝胶(in situ gel systems for the oral delivery of ibuprofen，IBU-ISG)， 并对其在Beagle犬上药代动力学进行了研究。以去乙酰结冷胶和海藻酸钠为凝胶材料， 分别对此两种凝胶材料进行了单因素考察， 初步确定了辅料的用量。以成胶前的复合黏度值、 体外释放度等参数为评价指标， 采用正交设计法进行处方优化。优化的制剂处方为： 1.0%海藻酸钠、 0.5%去乙酰结冷胶、 0.21%枸橼酸钠和0.056%氯化钙。采用RP-HPLC法测定6只Beagle犬口服IBU-ISG和参比制剂(市售布洛芬混悬液)后不同时间血浆中布洛芬的浓度， 所得药代动力学参数T_max分别为(1.8±0.6)和(0.4±0.1) h， C_max分别为(29.2±7.6)和(37.8±2.2)μg·mL^-1， T_1/2分别为(2.3±0.5)和(2.0±0.9) h， AUC_0-t分别为(131.0±38.6)和(117.3±23.1)μg·mL^-1·h。结果表明， 采用去乙酰结冷胶和海藻酸钠二元骨架制备IBU-ISG可行。     

In Vitro-In Vivo Evaluation of a Controlled Release Buccal Bioadhesive Device for Oral Drug Delivery

Purpose. To investigate the use of buccal bioadhesive device in targeting controlled drug delivery to the gastrointestinal tract. Methods. A three-leg crossover study was designed to evaluate the application of buccal bioadhesive device for providing controlled drug delivery to the gastrointestinal tract of a model drug cyanocobalamin in four healthy adult male beagle dogs. Results. In vitro dissolution studies using deionized water as the medium indicated that 100% of the drug was released within 15 min from a immediate release oral capsule formulation, whereas 90% of the drug was released within a period of 18 hrs from a buccal bioadhesive device formulation. Drug release from the buccal bioadhesive devices appeared to follow Higuchi's square root of time dependent model. The terminal half-life of the drug following I.V. administration in four dogs was found to be 16.4 ± 2.4 hrs. Following immediate release oral capsule administration of the drug C_max, t_max and bioavailability were 2333 ± 1469 ng/L, 2.5± 1.0 hrs and 14.1 ± 7.9%, respectively. Following buccal bioadhesive device administration of the drug C_max, t_max and bioavailability were 4154 ± 1096 ng/L, 11 ± 1.2 hrs and 35.8 ± 4.1%, respectively. Significantly higher bioavailability of the drug was observed with the buccal bioadhesive device administration when compared to the immediate release oral capsule. Conclusions. The buccal bioadhesive device appears to improve the oral bioavailability of cyanocobalamin by providing controlled delivery of the drug to the gastrointestinal tract.     

Pharmacokinetics of Memantine after a Single and Multiple Dose of Oral and Patch Administration in Rats

Memantine is a non‐competitive N‐methyl‐D‐aspartate (NMDA) receptor antagonist used to treat Alzheimer's disease. We investigated memantine pharmacokinetics after oral, IV and patch administration in rats, and compared memantine pharmacokinetics after multiple‐ or single‐dose oral and transdermal administration. Venous blood was collected at preset intervals in single‐ and multiple‐dose studies. Non‐compartmental pharmacokinetics was analysed for all formulations. The oral, IV and patch memantine doses were 10 mg/kg, 2 mg/kg and 8.21 ± 0.89 mg/kg, respectively. The maximum plasma concentration was lower and the half‐life longer after patch administration than oral and IV administration. Memantine bioavailability was 41 and 63% for oral and patch administration, respectively. Steady state was achieved around 24 hr for oral and patch administration. The mean AUC increased after oral or patch administration from single to multiple dose. The memantine patch formulation displayed a longer duration of action and lower peak plasma concentration. However, drug exposure was similar to the oral formulation at each dose. Additionally, the memantine patch formulation displayed a smaller interindividual variability and lower accumulation than the oral formulation.     

Investigations on the Percutaneous Absorption of the Antidepressant Rolipram in Vitro and in Vivo

In vitro experiments using full-thickness human skin showed that it was feasible to deliver therapeutic amounts of the new antidepressant drug rolipram. Simple transdermal devices were constructed, and the presence of isopropyl myristate (IPM) in a silicone adhesive (Dow Corning X7-2920) enhanced the flux across excised human skin. The steady-state fluxes from adhesive mixtures containing 0, 5, and 10% IPM were 3, 5.2, and 6 µg/cm²/hr, respectively. The in vitro experiments were confirmed in a clinical study involving six healthy male volunteers. The formulations tested were an alcoholic solution and adhesive patches containing 5 and 10% IPM. The dose of drug administered was 0.5 mg/cm² and the device size 25 cm². Blood samples were withdrawn over a 24-hr period and analyzed using radioimmunoassay. The topical applications were well tolerated, with only mild or no side effects. A lag time of approximately 2 hr was found for the detection of rolipram in the plasma (detection limit, 50 pg/ml). Interindividual variations both for the peak drug levels and throughout the delivery were quite high but this magnitude of variation has been observed in many other transdermal studies. Plasma levels between 1 and 2 ng/ml were found for all formulations and the AUC_0–30hr was significantly higher for the patch containing 5% IPM.     

Pharmacokinetics of Ketorolac and p-Hydroxyketorolac Following Oral and Intramuscular Administration of Ketorolac Tromethamine

Ketorolac tromethamine (KT), a potent analgesic with cyclooxygenase inhibitory activity, was administered in an open, randomized, single-dose study of Latin-square design to 12 healthy male volunteers. Doses of 30 mg oral (po) and 30, 60, and 90 mg intramuscular (im) KT were administered in solution. Plasma samples were analyzed for ketorolac (K) and its inactive metabolite, p-hydroxyketorolac (PHK), by reversed-phase high-performance liquid chromatography (HPLC). The 30-mg im dose was found to be similar to the 30-mg po dose with respect to total AUC values for both K and PHK. The amount of PHK circulating in plasma was very low as judged by AUC ratios (PHK/K × 100) of 1.9 and 1.5% for the 30-mg po and im doses, respectively. The rate of absorption of K and formation of PHK, as determined by C _max and T _max values, was significantly slower following the im doses. Total AUC and C _max for K and PHK increased linearly with dose after im administration of 30, 60, and 90 mg of KT. The mean plasma half-life of K was remarkably consistent between po and im administration and was independent of dose, ranging from 5.21 to 5.56 hr. The plasma metabolic profile was similar following both routes of administration and graded im doses.     

Oral Absorption of FK506 in Rats

The oral absorption of FK506 in solid dispersion formulation was studied in rats. The obtained area under the concentration versus time curve (AUC) increased in a nonlinear fashion with a small dose-dependent increase in the peak blood concentrations (C _max). The peak concentration time (T _max) was observed within 30 min after administration in all dosing groups (1–10 mg/kg) with or without feeding, whereas the oral absorption of FK506 was reduced to about 50% by gavage at a dose of 1 mg/kg. Participation of first-pass elimination was suggested by comparing the blood levels after infusion via the portal vein with those after infusion via the femoral vein. Further, in an in vitro stability study and an in situ loop absorption study, FK506 was fairly stable in the gastrointestinal juice and was absorbed predominantly from the upper part of the small intestine.     

噻吗心安经皮吸收制剂的体内生物利用度

噻吗心安经皮吸收制剂选用PVA-0486作为骨架材料,由4层(背衬层、含药膜层、压敏胶层、保护层)组成。建立了HPLC方法检测血浆中噻吗心安的含量,以Zorbax ODS柱分离,流动相为乙腈—水—磷酸—三乙胺,在294 nm处检测,采用外标法峰面积定量。用本法对9名健康志愿者进行了噻吗心安贴剂和噻吗心安片剂的血药浓度测定,结果表明:噻吗心安贴剂贴用4 h开始达到治疗浓度,可持续32 h,血浓稳定,人体内为一室模型、零级吸收。     

Comparison of the dissolution and pharmacokinetic profiles of two galenical formulations of the endothelin receptor antagonist macitentan

Macitentan (ACT-064992) is an orally active endothelin receptor antagonist. We first compared the in vitro dissolution characteristics of uncoated and film-coated tablets with hard gelatin capsules containing 10 mg ACT-064992. Subsequently, we compared the oral pharmacokinetics of ACT-064992 and its active metabolite ACT-132577 of the coated tablet and the gelatin capsule formulation in 11 male volunteers.The dissolution profile showed a rapid disintegration of all formulations with >90% dissolution of ACT-064992 within 45 min. The pharmacokinetics of ACT-064992 and its metabolite ACT-132577 were comparable for the two formulations. ACT-064992 revealed a slow absorption (median t_max 8 h) and a terminal half-life of approximately 13 h. Bioequivalence criteria were met for AUC_0−t and AUC_0−∞. Mean C_max was 19% lower after ingestion of the tablet compared to capsules with its lower 90% confidence limit below the accepted bioequivalence range. The pharmacokinetics of the metabolite ACT-132577, characterized by a t_max of approximately 48 h and a terminal half-life of approximately 45 h, was not different between the two formulations.We conclude that the absorption profile of the tablet differs from the capsule in peak but not in total exposure, which is not expected to be of clinical significance.     

Bioavailability of dextromethorphan (as dextrorphan) from sustained release formulations in the presence of guaifenesin in human volunteers

A multiple dose bioavailability study with six healthy male human volunteers was conducted. The bioavailability of an experimental sustained release tablet containing dextromethorphan hydrobromide (DXP-HBr), was compared with a marketed sustained release DXP-HBr suspension in a three-way crossover study. Plasma samples, collected serially after oral drug administration, were analysed for the major metabolite of dextromethorphan (DXP), dextrorphan (DX), using a specific HPLC method with fluorescence detection. The bioavailability parameters; area under the concentration–time curve (AUC), maximum plasma concentration (C_max), and time to peak (T_max), were obtained from the plasma concentration–time data. Additionally, pharmacokinetic parameters such as mean residence time (MRT), accumulation factor (R), fluctuation index (F_i), total body clearance (Cl), and the average concentration (C ¯) were estimated by using model independent kinetics approach. Analysis of variance of the data revealed that the presence of guaifenesin in the test formulation does not appear to have a statistically significant (p >0.05) effect on the bioavailability of dextromethorphan as dextrorphan. The relative bioavailability of the tablet dosage form with respect to the suspension was found to be 113% on Day 1 and 110% on Day 6. Copyright © 1998 John Wiley & Sons, Ltd.     

Analysis of urinary andrographolides and antioxidant status after oral administration of Andrographis paniculata leaf extract in rats

A simple high-performance liquid chromatography (HPLC) method was developed to determine the content of andrographolide (AP) and 14-deoxy-11,12-dideoxyandrographolide (DIAP) in a pooled urine of rat obtained within 24 h after an oral dose of Andrographis paniculata leaf extract at 1 g/kg body weight. Cumulative urinary excretion of AP and DIAP in 24 h after oral administration of the extract was 0.88% and 1.61% of oral dose administered, respectively. The extract showed significant reduction (p < 0.05) of MDA levels and elevation of total antioxidant status in rat urine samples collected in 24 after oral administration.     

Effect of Nanonization on Absorption of 301029: Ex Vivo and In Vivo Pharmacokinetic Correlations Determined by Liquid Chromatography/Mass Spectrometry

Purpose. To compare Caco-2 monolayer permeability and in vivo bioavailability of microparticle with nanoparticle 301029, a thiadiazole derivative, and to determine whether nanonization could improve oral bioavailability of the poorly soluble compound. Methods. The mean particle size of 301029 was reduced from 7 m to 280 nm by pearl milling. In the ex vivo assay, both microparticle and nanoparticle 301029 at the same concentration were separately added to apical side and were collected from basolateral side of Caco-2 monolayer. In the bioavailability study, the two particle sizes of 301029 were orally administered to rats, respectively, and blood samples were collected. Nanoparticle 301029 in culture medium and rat serum was detected by a liquid chomatography-mass spectrometer (LC/MS) coupled with atmospheric pressure chemical ionization (APCI). Results. Permeability rate and permeated amounts of nanoparticle 301029 across the Caco-2 monolayer were about four times higher than those of microparticle 301029. In a pharmacokinetic study, nanoparticle 301029 showed T_max about 1 h, whereas the microparticle 301029 showed T_max at 4 h. The C_max and AUC of nanoparticle 301029 were 3- to 4-fold greater than those of microparticle 301029, resulting in a significant increase in oral bioavailability of 301029 as compared with microparticle 301029. The ex vivo permeability and in vivo pharmacokinetic data indicate that nanoparticle formulation improves both absorption rate and absorption extent of the poorly soluble drug. Conclusions. Nanoparticle formulation enhances both Caco-2 monolayer permeability and rat oral bioavailability of the poorly soluble 301029. The result also demonstrates a close correlation between ex vivo Caco-2 permeability model and in vivo gastrointestinal absorption.     

Evaluation of Bioadhesive Capacity and Immunoadjuvant Properties of Vitamin B<Subscript>12</Subscript>-Gantrez Nanoparticles

Purpose  To design bioadhesive Gantrez AN (poly[methyl vinyl ether-co-maleic anhydride], PVM/MA) nanoparticles (NP) coated with vitamin B₁₂ (Vit B₁₂), and investigate their application in oral antigen delivery. Methods  The association of Vit B₁₂ to Gantrez AN nanoparticles was performed by the direct attachment of reactive Vit B₁₂ to the surface of the nanoparticles (NPB), or linking to the copolymer chains in dimethylformamide prior to NP formation (NPB-DMF). Nanoparticles were characterized by measuring the size, zeta potential, Vit B₁₂ association efficacy, and stability of Vit B₁₂ on the surface of the nanoparticles. In vivo bioadhesion study was performed by the oral administration of fluorescently-labeled nanoparticle formulations to rats. Both systemic and mucosal immune responses were evaluated after oral and subcutaneous immunization with ovalbumin (OVA) containing Vit B₁₂-coated nanoparticles. Results  The Vit B₁₂ nanoparticles displayed homogenous size distribution with a mean diameter of about 200 nm and a negative surface charge. The association efficiency of Vit B₁₂ to NPB-DMF formulation was about two times higher than to the NPB, showing also a higher surface stability of Vit B₁₂. The bioadhesion study demonstrated that NPB-DMF had an important tropism to the distal portions of the gut, which was about two and 3.5 times higher than the tropism observed for NPB and control NP, respectively (p < 0.05). Oral administration of OVA-NPB-DMF induced also stronger and more balanced serum anti-OVA titers of IgG2a (Th1) and IgG1 (Th2) compared to control OVA-NP. In addition, oral immunization with OVA-NPB-DMF induced a higher mucosal IgA response than subcutaneous administration. Conclusions  These results indicate the benefits of bioadhesive Vit B₁₂-coated nanoparticles in oral antigen delivery eliciting systemic and mucosal immune response.     

Development and Evaluation of HPMC Based Matrices for Transdermal Patches of Tramadol

A matrix dispersion type transdermal delivery system of tramadol was designed and developed using different concentrations and polymeric grades of Hydroxypropyl Methylcellulose (HPMC K4M, K15M & K100M). Formulations were selected on the basis of their drug release content and release pattern. Films were evaluated for their physicochemical characteristics, followed by in vitro and in vivo evaluation. The possible drug-polymer interaction was studied by FTIR, DSC and X-RD studies. These were evaluated for in vitro dissolution characteristic using Cygnus' sandwich patch holder. The drug release followed Higuchi kinetics (r?=?0.979–998; P < 0.001). In vivo evaluation was carried out on healthy rabbits of either sex, following balanced incomplete block design. The in vitro dissolution rate constant, dissolution half life and pharmacokinetic parameters generated from plasma (t_max, C_max, AUC_(s), t_1/2, K_el, and MRT) were evaluated statistically by two-way ANOVA. Statistically a good correlation was found between percent of drug absorbed from patches versus AUCs. Percent of drug dissolved at a given time versus plasma drug concentration correlated statistically. The results of this study indicate that the polymeric matrix type transdermal films of tramadol hold potential for transdermal delivery on the basis of their in vitro and pharmacokinetic results.     

Development and in Vitro-in Vivo Evaluation of a Multiparticulate Sustained Release Formulation of Diltiazem

Purpose. To develop and evaluate the in vitro/in vivo performance of diltiazem sustained release pellets that were prepared by the Wurster column process. Methods. Pellets containing diltiazem were prepared by spraying a slurry of micronized diltiazem hydrochloride, pharmaceutical glaze and alcohol onto an appropriate mesh fraction of nonpareil seeds using the Wurster column. A two-step drug layering process was used to increase drug loading from 60% to 75%. The oven-dried diltiazem basic pellets were coated with eth-ylcellulose/dibutyl sebacate coating solution to yield diltiazem sustained release pellets. An open, randomized Latin square, three-way crossover clinical study was used to evaluate the in vivo performance of the coated product. Results. Altering the mesh fraction of the starting nonpareil seeds for this layering process was found to affect the release characteristics of drug from the pellets. An oven-drying step was required to stabilize the diltiazem basic pellets. The thicker the drug loading layer the longer the oven drying is needed to stabilize the pellets. The diltiazem sustained release pellets produced by these methods displayed sustained release dissolution profiles both in vitro and in vivo. Diltiazem basic pellets coated with a 0.6% ethylcellulose/dibutyl sebacate coating showed a different rate of absorption (lower C _max and higherT _max) and the same extent of absorption as compared to Cardizem^® tablets. Conclusions. Clinical data confirmed that this formulation approach is an effective means to produce a diltiazem sustained release product.     

Antihypertensive and vasorelaxant activities of Laelia autumnalis are mainly through calcium channel blockade

The aim of the present study was to evaluate the possible mechanism of the vasorelaxant action of methanol extract from Laelia autumnalis (MELa) in isolated rat aortic rings, and to establish its antihypertensive activity in vivo. MELa (0.15→50 µg/mL) induced relaxation in aortic rings pre-contracted with KCl (80 mM), showing an IC₅₀ value of 34.61 ± 1.41 µg/mL and E_max value of 85.0 ± 4.38% (in endothelium-intact rings) and an IC₅₀ value of 45.11 ± 4.17 µg/mL and E_max value of 80.0 ± 12.1% (in endothelium-denuded rings). Serotonin (5-HT, 1 × 10^− 4 M) provoked sustained contraction, which was markedly inhibited by MELa (0.15→50 µg/mL) in a concentration-dependent and endothelium-independent manner. Pretreatment with MELa (15, 46, 150, 300 and 1500 µg/mL) also inhibited contractile responses to norepinephrine (NE 1 × 10^− 11 M to 1 × 10^− 5.5 M). In endothelium-denuded rings, the vasorelaxant effect of MELa was reduced partially by ODQ (1 µM), but not by tetraethylammonium (5 µM), glibenclamide (10 µM), and 2-aminopyridine (100 µM). The extract also reduced NE-induced transient contraction in Ca²⁺-free solution, and inhibited contraction induced by increasing external calcium in Ca²⁺-free medium plus high KCl (80 mM). The antihypertensive effect of MELa was determined in spontaneously hypertensive rats (SHR). A single oral administration of the extract (100 mg/kg) exhibited a significant decrease in systolic and diastolic blood pressure and heart rate (p < 0.05) in SHR rats. Our results suggest that MELa induces relaxation in rat aortic rings through an endothelium-independent pathway, involving blockade of Ca²⁺ channels and a possible cGMP enhanced concentrations and also causes an antihypertensive effect.     

Butriptyline: Human pharmacokinetics and comparative bioavailability of conventional and sustained release formulations

The pharmacokinetics and relative bioavailability of butriptyline from conventional and a sustained release (SR) formulation have been studied in a panel of 14 volunteers. A single oral dose of 75 mg butriptyline hydrochloride was administered and a 2 × 2 latin square design was followed. Pharmacokinetic modelling has shown that the plasma butriptyline concentration/time profile is adequately described by a two-compartment open model; good agreement was obtained for the model-fitted and measured parameters. The SR formulation was shown to possess sustained release characteristics as evidenced by the increase in T_max for 2.6 to 7.5 h, the decrease in C_max from 46.5 to 20.3 ng ml^?1, and a three-fold increase in ‘half-value duration’ (HVD). The changes have been achieved without any significant decrease in the relative bioavailability of the SR formulation. The half-life of butriptyline in plasma was about 20 h and was not formulation dependant.     

Single-dose bioavailability of oral and intramuscular thiocolchicoside in healthy volunteers

A single dose of 8 mg of thiocolchicoside was administered to 12 healthy volunteers according to a Latin square design, either as tablets (reference), oral solution, or intramuscular injection. Serum thiocolchicoside concentrations showed an absorption phase followed by a biexponential decay with a terminal half-life (t_1/2β) of approximately 5 h, similar for the three formulations. The relative bioavailability of both oral formulations was approximately 25%, compared to the intramuscular formulation. There was a trend for the oral solution to have a slightly larger AUC and C_max, as well as a slightly shorter T_max, than the tablet formulation. However, the comparison of the two oral forms did not show statistically significant differences in the pharmacokinetic parameters C_max, T_max, and AUC, suggesting that the Coltramyl^® tablets have an adequate in vivo dissolution profile.