Displaying publications 1 - 20 of 28 in total

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  1. Hartanto, F.K., Auzair, L., Mohd Tahir, N.F., Harun, N., Aung, L.O., Siar, C.H., et al.
    Ann Dent, 2013;20(2):29-33.
    MyJurnal
    Conventional oral squamous cell carcinomas are readily
    recognized histopathologically but the presence of
    additional atypical features may be challenging from
    a diagnostic point of view. We present a case of a welldifferentiated
    oral squamous cell carcinoma with pseudoglandular
    differentiation and discuss the possible differential
    diagnoses on a histopathological basis. Accurate diagnosis
    is imperative for timely and appropriate intervention and
    denotes distinctive prognostic implications. The presence
    of perivascular and perineural infiltrations as observed in
    this case would indicate the need for further post-operative
    therapeutic decision-making aimed at controlling local
    spread as well as distant metastases
  2. Arumugam M, Leelavathi M, Harun NL, Jamil A
    Med J Malaysia, 2021 07;76(4):583-584.
    PMID: 34305124
    Cutaneous sporotrichosis (CS) presents as asymptomatic lesions of varied morphology. The most common variant is the lymphocutaneous type which typically progresses from a papule to an ulcer and then forms nodules along the superficial lymphatic channels. Diagnosis CS may be challenging when the lesion presents at an uncommon site where the superficial lymphatic drainage is unfamiliar. We present here a case of sporotrichosis of the abdominal wall which was initially misdiagnosed as an abscess but later confirmed by culture and managed successfully.
  3. Jamani NA, Ardini YD, Harun NA
    Med J Malaysia, 2020 07;75(4):439-441.
    PMID: 32724012
    Ankyloglossia is a congenital anomaly which may reduce or restrict the tongue tip mobility. The restricted mobility is caused by an unusual short, thick lingual frenum. This condition may cause various problems in infants including breastfeeding in the new-borns. This case report describes 3 cases of ankyloglossia affecting breastfeeding and highlights the experiences of the mothers and their difficulties in breastfeeding babies with it. Comprehensive feeding examination was accomplished, the primary cause of feeding issues was identified, and frenotomy intervention was provided. Post frenotomy, infants were able to breastfeed easily and this was beneficial in continuation of breastfeeding and pain reduction in mothers.
  4. Panirselvam RR, Ramly SS, Harun NA
    MyJurnal
    Systemic lupus erythematosus (SLE) is a debilitating and chronic autoimmune disease which strikes insidiously. The disease currently has a prevalence of 43/ 100 000 individuals in Malaysia. The presentation of the disease is varied resulting in delay in diagnosis and onset of complications prior to management. The disease commonly presents as joint pain and cutaneous manifestations. Neuropsychiatric presentation accounts for 24% of symptoms during onset of illness. This case report highlights that we encountered a patient who presented with neuropsychiatric manifestations, whereby the patient was managed for the psychiatric symptoms prior to the organic diagnosis being made.
  5. Ong TK, Harun N, Lim TW
    Eur Endod J, 2019;4(2):90-95.
    PMID: 32161894 DOI: 10.14744/eej.2019.13007
    In this case report, three teeth with complete or incomplete cemental tear in two patients were presented. Even though periapical radiograph could detect cemental tear in these three teeth, the cone-beam computed tomography scanning clearly revealed the pattern of the cemental tear, which was later confirmed by histopathological examination. Therefore, this case report shows the benefits of incorporating both cone-beam computed tomography and histopathological examination to diagnose cemental tear.
  6. Harun N, Anderson RA, Miller EI
    J Anal Toxicol, 2009 8 6;33(6):310-21.
    PMID: 19653934 DOI: 10.1093/jat/33.6.310
    An ELISA and a liquid chromatography-tandem mass spectrometry (LC-MS-MS) confirmation method were developed and validated for the identification and quantitation of ketamine and its major metabolite norketamine in urine samples. The Neogen ketamine microplate ELISA was optimized with respect to sample and enzyme conjugate volumes and the sample preincubation time before addition of the enzyme conjugate. The ELISA kit was validated to include an assessment of the dose-response curve, intra- and interday precision, limit of detection (LOD), and cross-reactivity. The sensitivity and specificity were calculated by comparison to the results from the validated LC-MS-MS confirmation method. An LC-MS-MS method was developed and validated with respect to LOD, lower limit of quantitation (LLOQ), linearity, recovery, intra- and interday precision, and matrix effects. The ELISA dose-response curve was a typical S-shaped binding curve, with a linear portion of the graph observed between 25 and 500 ng/mL for ketamine. The cross-reactivity of 200 ng/mL norketamine to ketamine was 2.1%, and no cross-reactivity was detected with 13 common drugs tested at 10,000 ng/mL. The ELISA LOD was calculated to be 5 ng/mL. Both intra- (n = 10) and interday (n = 50) precisions were below 5.0% at 25 ng/mL. The LOD for ketamine and norketamine was calculated statistically to be 0.6 ng/mL. The LLOQ values were also calculated statistically and were 1.9 ng/mL and 2.1 ng/mL for ketamine and norketamine, respectively. The test linearity was 0-1200 ng/mL with correlation coefficient (R(2)) > 0.99 for both analytes. Recoveries at 50, 500, and 1000 ng/mL range from 97.9% to 113.3%. Intra- (n = 5) and interday (n = 25) precisions between extracts for ketamine and norketamine were excellent (< 10%). Matrix effects analysis showed an average ion suppression of 5.7% for ketamine and an average ion enhancement of 13.0% for norketamine for urine samples collected from six individuals. A comparison of ELISA and LC-MS-MS results demonstrated a sensitivity, specificity, and efficiency of 100%. These results indicated that a cutoff value of 25 ng/mL ketamine in the ELISA screen is particularly suitable and reliable for urine testing in a forensic toxicology setting. Furthermore, both ketamine and norketamine were detected in all 34 urine samples collected from individuals socializing in pubs by the Royal Malaysian Police. Ketamine concentrations detected by LC-MS-MS ranged from 22 to 31,670 ng/mL, and norketamine concentrations ranged from 25 to 10,990 ng/mL. The concentrations of ketamine and norketamine detected in the samples are most ikely indicative of ketamine abuse.
  7. Harun NA, Finlay AY, Salek M, Piguet V
    Br J Dermatol, 2016 Sep;175(3):572-82.
    PMID: 27060980 DOI: 10.1111/bjd.14650
    BACKGROUND: Although multiple factors influence discharge decisions, there is no structured guidance to assist clinicians in making informed decisions. A discharge information checklist might improve the appropriateness of dermatology clinicians' discharge decisions.

    OBJECTIVES: To generate consensus among dermatologists on the content of an outpatient discharge checklist, to create one and to seek clinicians' opinions on its usefulness.

    METHODS: Seventeen consultant dermatologists from five National Health Service trusts completed a 72-item Delphi questionnaire. A five-point Likert scale was used to rate each item for importance in contributing to a high-quality discharge decision. Eighteen clinicians completed a questionnaire evaluating checklist use.

    RESULTS: Consensus was determined when ≥ 75% of consultants rated an item 'very important' or 'important'. There was strong inter-rater reliability (intraclass correlation coefficient = 0·958) and fair inter-rater agreement (Fleiss kappa = 0·269). There were 26 consensus-agreed items, condensed to 13 that formed the 'traffic-light' checklist. These are disease-related issues (diagnostic certainty, disease severity, treatment appropriateness, patient manageable in primary care, patient's benefit from follow-up), patient empowerment issues (understanding diagnosis and treatment outcome, having a clear plan, treatment side-effects, ability to self-manage) and addressing concerns (patient concerns, easy reaccess to secondary care, whether patient and clinician are happy with the decision). Twelve clinicians (67%) found the checklist useful, 11 (61%) wanted to use it in future, 10 (56%) thought it was useful for training and three (17%) said it helped their thinking. Clinicians suggested its use for auditing and for training clinicians and administrators.

    CONCLUSIONS: Items were identified to create an outpatient discharge information checklist, which demonstrated high acceptability.

  8. Harun N, Hassan Z, Navaratnam V, Mansor SM, Shoaib M
    Psychopharmacology (Berl), 2015 Jul;232(13):2227-38.
    PMID: 25616583 DOI: 10.1007/s00213-015-3866-5
    RATIONALE: Mitragynine (MG) is the primary active alkaloid extracted from the leaves of Mitragyna speciosa or kratom and exhibits pharmacological activities mediated by opioid receptors. The plant has been traditionally used for its opium and psychostimulant-like effects to increase work efficiency or as a substitute in the self-treatment of opiate addiction.

    OBJECTIVES: The present study was performed to investigate the discriminative stimulus effects of MG in rats. The pharmacological mechanism of MG action and its derivative, 7-hydroxymitragynine (7-HMG) with a specific focus on opioid receptor involvement was examined in rats trained to discriminate morphine from vehicle. In order to study the dual actions of MG, the effect of cocaine substitution to the MG discriminative stimulus was also performed in MG-trained rats.

    METHODS: Male Sprague Dawley rats were trained to discriminate MG from vehicle in a two-lever drug discrimination procedure under a tandem variable-interval (VI 60') fixed-ratio (FR 10) schedule of food reinforcement.

    RESULTS: Rats acquired the MG discrimination (15.0 mg/kg, i.p.) which was similar to the acquisition of morphine discrimination (5.0 mg/kg, i.p.) in another group of rats. MG substituted fully to the morphine discriminative stimulus in a dose-dependent manner, suggesting pharmacological similarities between the two drugs. The administration of 7-HMG derivative in 3.0 mg/kg (i.p.) dose engendered full generalisation to the morphine discriminative stimulus. In addition, the MG stimulus also partially generalised to cocaine (10.0 mg/kg, i.p.) stimulus.

    CONCLUSION: The present study demonstrates that the discriminative stimulus effect of MG possesses both opioid- and psychostimulant-like subjective effects.

  9. Harun N, Johari IS, Mansor SM, Shoaib M
    Psychopharmacology (Berl), 2020 Mar;237(3):855-867.
    PMID: 31832720 DOI: 10.1007/s00213-019-05418-6
    RATIONALE: Kratom is proposed to exhibit therapeutic potential as an opium substitute, but little is known about its dependence-producing profile, particularly of its main psychoactive compound, mitragynine (MG).

    OBJECTIVES: This study examined the dependence-producing effects of MG using operant-scheduled behaviour in rats and investigated the potential therapeutic effect of MG by comparing effects to buprenorphine in morphine-dependent rats using the same schedule-controlled behavioural task.

    METHODS: The effects of acutely administered MG and morphine were determined in rats trained to respond under fixed-ratio (FR) 10 schedule of food reinforcement. Next, the rats were administered MG and morphine twice daily for 14 consecutive days to determine if physiological dependence would develop by examining cessation of drug treatment and following antagonist-precipitated withdrawal. The study then examined the effects of MG substitution to suppress naloxone-precipitated morphine withdrawal effects on scheduled responding.

    RESULTS: Acute doses of MG did not produce dose-related decreases on FR schedules of responding compared to morphine. Unlike morphine, MG-treated rats showed no suppression of response rates following cessation of MG treatment. However, withdrawal effects were evident for MG after precipitation by either naloxone or SR141716A (rimonabant), similar to morphine-treated rats. MG in higher doses (10 and 30 mg/kg) attenuated the naloxone-precipitated morphine withdrawal effects while smaller doses of buprenorphine (0.3 and 1.0 mg/kg) were necessary to alleviate these effects.

    CONCLUSION: The findings suggest that MG does not induce physiological dependence but can alleviate the physical symptoms associated with morphine withdrawal which represent the desired characteristics of novel pharmacotherapeutic interventions for managing opioid use disorder (OUD).

  10. Harun N, Kamaruzaman NA, Mohamed Sofian Z, Hassan Z
    Neurosci Lett, 2022 Jan 31;773:136500.
    PMID: 35114335 DOI: 10.1016/j.neulet.2022.136500
    Opioid use disorder (OUD) has become a significant public health issue worldwide. Methadone and buprenorphine are the most common medications used for treating OUD. These drugs have the potential to assist many patients in managing their opioid dependence and withdrawal but they are currently misused and associated with certain compliance issues, side effects, and risk of relapse. As an opioid-like herbal supplement, Mitragyna speciosa Korth or kratom has received increased attention for managing chronic pain and opioid withdrawal symptoms. Nevertheless, the use of kratom as a self-treatment medication for opioid dependence continues to be controversial due to concerns raised about its effectiveness, safety, and abuse liability. The main active alkaloid constituent of the plant, mitragynine, has been shown to act as a partial mu-opioid agonist. Given this pharmacology, studies have been focusing on this psychoactive compound to examine its potential therapeutic values as medication-assisted therapy (MAT). This review aims to provide a current preclinical overview of mitragynine as a prospective novel option for MAT and summarise the recent developments in determining if the plant's active alkaloid could provide an alternative to opioids in the treatment of OUD.
  11. Harun NA, Finlay AY, Salek MS, Piguet V
    Br J Dermatol, 2015 Sep;173(3):720-30.
    PMID: 26076194 DOI: 10.1111/bjd.13946
    BACKGROUND: Outpatient discharge decision making in dermatology is poorly understood.
    OBJECTIVE: To identify the influences on clinicians' thought processes when making discharge decisions in dermatology outpatient clinics.
    METHODS: Forty clinicians from 11 National Health Service Trusts in England were interviewed. The interviews were audiorecorded, transcribed, coded and thematically analysed.
    RESULTS: The mean age of the clinicians was 48.8 years (range 33.0-67.0), 17 (43%) were men and 19 (48%) had > 20 years of clinical experience. One hundred and forty-eight influences were reported, with five main themes: (i) disease-based influences included type of diagnosis (100% of clinicians), guidelines (100%) and treatment needed (100%); (ii) clinician-based influences included the clinician's level of experience (100%), seniority (37%), emotional attitude (95%), 'gut feeling' (25%), personal attitude towards discharge (45%) and level of perception (100%); (iii) patient-based influences included patients' ability to cope with their disease (100%), wishes (70%), quality of life (32%), command of English (40%) and cultural background (25%); (iv) practice-based influences included good primary care (100%), secondary support structure (100%) and clinic capacity pressure (67%); (v) policy-based influences included pressure from hospital managers (57%) and an active discharge policy (7%). Fourteen (9%) influences were potentially inappropriate.
    CONCLUSION: This study has identified multiple factors influencing outpatient discharge decision making. This provides the basis for developing evidence-based training to improve discharge decision appropriateness.
  12. Johari IS, Harun N, Sofian ZM, Shoaib M
    Psychopharmacology (Berl), 2021 Nov;238(11):3183-3191.
    PMID: 34333672 DOI: 10.1007/s00213-021-05934-4
    RATIONALE: Kratom (Mitragyna speciosa Korth), a native medicinal plant of Southeast Asia, is proposed to exhibit potential therapeutic value as an opioid substitute. However, studies of its negative emotional states resulting from withdrawal particularly of its main psychoactive compound, mitragynine (MG), are limited.

    OBJECTIVES: Using the pentylenetetrazol (PTZ) discrimination assay, this study aims to investigate the effects of MG in responding to the PTZ stimulus and to assess the generalisation effects of withdrawal from MG to the PTZ stimulus.

    METHODS: Rats (n = 20) were trained on a tandem (FR-10, VI-15) schedule of food reinforcement to press one lever after administration of the anxiogenic compound PTZ (16 mg/kg, i.p.) and an alternate lever after vehicle. Following acute tests, training was suspended, and rats were chronically treated with MG or morphine at 8-h intervals for 9 days and withdrawal was precipitated on the tenth day using naloxone (1 mg/kg, i.p.). The rats were tested for generalisation to PTZ at 2, 8 and 24 h after the last dose of MG or morphine administration.

    RESULTS: Unlike morphine that produced dose-related PTZ-like stimulus, MG at 3, 10, 30 and 45 mg/kg doses showed no substitution to the PTZ discriminative stimulus. In contrast to morphine which produced a time-dependent generalisation to the PTZ stimulus, naloxone did not precipitate withdrawal effects in MG-treated rats as they selected the vehicle lever at three withdrawal time points.

    CONCLUSION: These results demonstrate that MG produces a very different response to morphine withdrawal that is not associated with anxiogenic-like subjective symptoms. These characteristics of MG may provide further support for use as a novel pharmacotherapeutic intervention for managing opioid use disorder.

  13. Japarin RA, Harun N, Hassan Z, Müller CP
    Behav Brain Res, 2023 Sep 13;453:114638.
    PMID: 37619769 DOI: 10.1016/j.bbr.2023.114638
    Mitragynine (MG) is the primary active constituent of Mitragyna speciosa Korth (kratom), a psychoactive Southeast Asian plant with potential therapeutic use. Numerous studies support roles of dopaminergic system in drug reward. However, the involvement of the dopaminergic system in mediating MG reward and drug-seeking is poorly understood. Using conditioned place preference (CPP) paradigm, the present study aims to evaluate the roles of the dopamine (DA) D1 receptor in the acquisition and expression of MG-induced CPP in rats. The effects of SCH-23390, a selective DA D1 receptor antagonist, on the acquisition of MG-induced CPP were first investigated. Rats were pre-treated systemically with SCH-23390 (0, 0.1 and 0.3 mg/kg, i.p.) prior to MG (10 mg/kg) conditioning sessions. Next, we tested the effects of the DA D1 receptor antagonist on the expression of MG-induced CPP. Furthermore, the effects of a MG-priming dose (5 mg/kg) on the reinstatement of extinguished CPP were tested. The results showed that SCH-23390 dose-dependently suppressed the acquisition of a MG-induced CPP. In contrast, SCH-23390 had no effect on the expression of a MG-induced CPP. The findings of this study suggested a crucial role of the DA D1 receptor in the acquisition, but not the expression of the rewarding effects of MG in a CPP test. Furthermore, blockade of the D1-like receptor during conditioning did not prevent MG priming effects on CPP reinstatement test, suggesting no role for the DA D1 receptor in reinstatement sensitivity.
  14. Japarin RA, Harun N, Hassan Z, Shoaib M
    Behav Pharmacol, 2023 Apr 01;34(2-3):123-130.
    PMID: 36752325 DOI: 10.1097/FBP.0000000000000715
    Mitragynine (MG) is a pharmacologically active alkaloid derived from the leaves of Mitragyna speciosa Korth (Kratom). This plant has sparked significant interest as a potential alternative treatment for managing opioid dependence and withdrawal due to its opioid-like pharmacological effects. However, whether MG exposure would trigger opioid-seeking behaviour following abstinence has not been investigated. The present study examined the effects of MG priming on morphine-seeking behaviour in rats. Male Sprague-Dawley rats were initially trained to intravenously self-administer morphine (0.5 mg/kg/infusion) under a fixed ratio-3 schedule of reinforcement. Removal of both morphine infusions and drug-associated cues led to the subsequent extinction of the drug-seeking behaviour. Tests of reinstatement were made following exposure to a randomised order of intraperitoneal injections of MG (3, 10 and 30 mg/kg), morphine (5 mg/kg) and vehicle. Significant levels of drug-seeking behaviour were observed following extended access to morphine self-administration, which was extinguished following removal of morphine and cues indicative of morphine-seeking behaviour, supporting the relapse model. The present finding demonstrated that MG priming in a dose of 10 mg/kg resulted in the reinstatement of morphine-seeking behaviour, whereas the higher MG dose (30 mg/kg) tested suppressed the seeking response. This study indicated that exposure to a low MG dose may increase the likelihood of relapsing to opioids, suggesting that the potential of MG as a treatment for opioid management merits further scientific assessment of its ability to trigger relapse to opioid abuse.
  15. Al-Shibli SM, Harun N, Ashour AE, Mohd Kasmuri MHB, Mizan S
    PeerJ, 2019;7:e7624.
    PMID: 31592340 DOI: 10.7717/peerj.7624
    Obesity is demonstrated to be a risk factor in the development of cancers of various organs, such as colon, prostate, pancreas and so on. Leptine (LEP) is the most renowned of the adipokines. As a hormone, it mediates its effect through leptin receptor (LEPR), which is widely expressed in various tissues including colon mucosa. In this study, we have investigated the degree of expression of LEP and LEPR in colorectal cancer (CRC). We collected 44 surgically resected colon cancer tissues along with normal adjacent colon tissue (NACT) from a sample of CRC patients from the Malaysian population and looked for leptin and leptin receptors using immunohistochemistry (IHC). All the samples showed low presence of both LEP and LEPR in NACT, while both LEP and LEPR were present at high intensity in the cancerous tissues with 100% and 97.7% prevalence, respectively. Both were sparsed in the cytoplasm and were concentrated beneath the cell membrane. However, we did not find any significant correlation between their expression and pathological parameters like grade, tumor size, and lymph node involvement. Our study further emphasizes the possible causal role of LEP and LEPR with CRC, and also the prospect of using LEPR as a possible therapeutic target.
  16. DeSeta M, Baldwin D, Siddik D, Hullah E, Harun N, Yee R, et al.
    Br Dent J, 2020 09;229(5):287-291.
    PMID: 32918012 DOI: 10.1038/s41415-020-2023-7
    Introduction This case series highlights the condition juvenile spongiotic gingivitis; how to recognise it, where it lies in a list of differential diagnoses and why conservative management is the authors' recommended treatment.Case series The authors present ten cases that were successfully managed conservatively on the Joint Oral Medicine Paediatric Dentistry Clinic at Guy's and St Thomas' NHS Foundation Trust over a six-year period. Follow-ups reached up to 5 years and 11 months to date, with no adverse outcomes observed in any of the cases.Conclusion The pathogenesis of this benign condition and its ideal management is not well understood. Recurrence can occur after surgical treatment and the condition is likely to spontaneously resolve or regress with age. Therefore, particularly in asymptomatic cases, conservative management is recommended.
  17. Jusoh N, Yeong YF, Lock SSM, Yub Harun N, Mohd Yusoff MH
    Polymers (Basel), 2019 Nov 04;11(11).
    PMID: 31689895 DOI: 10.3390/polym11111807
    The bottleneck of conventional polymeric membranes applied in industry has a tradeoff between permeability and selectivity that deters its widespread expansion. This can be circumvented through a hybrid membrane that utilizes the advantages of inorganic and polymer materials to improve the gas separation performance. The approach can be further enhanced through the incorporation of amine-impregnated fillers that has the potential to minimize defects while simultaneously enhancing gas affinity. An innovative combination between impregnated Linde T with different numbers of amine-functional groups (i.e., monoamine, diamine, and triamine) and 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA)-derived polyimide has been elucidated to explore its potential in CO2/CH4 separation. Detailed physical properties (i.e., free volume and glass transition temperature) and gas transport behavior (i.e., solubility, permeability, and diffusivity) of the fabricated membranes have been examined to unveil the effect of different numbers of amine-functional groups in Linde T fillers. It was found that a hybrid membrane impregnated with Linde T using a diamine functional group demonstrated the highest improvement compared to a pristine polyimide with 3.75- and 1.75-fold enhancements in CO2/CH4 selectivities and CO2 permeability, respectively, which successfully lies on the 2008 Robeson's upper bound. The novel coupling of diamine-impregnated Linde T and 6FDA-derived polyimide is a promising candidate for application in large-scale CO2 removal processes.
  18. Japarin RA, Yusoff NH, Hassan Z, Müller CP, Harun N
    Behav Brain Res, 2021 02 05;399:113021.
    PMID: 33227244 DOI: 10.1016/j.bbr.2020.113021
    Kratom is a medicinal plant that exhibits promising results as an opiate substitute. However, there is little information regarding the abuse profile of its main psychoactive constituent, mitragynine (MG), particularly in relapse to drug abuse. Using the place conditioning procedure as a model of relapse, this study aims to evaluate the ability of MG to induce conditioned place preference (CPP) reinstatement in rats. To evaluate the cross-reinstatement effects, MG and morphine were injected to rats that previously extinguished a morphine- or MG-induced CPP. Following a CPP acquisition induced by either MG (10 and 30 mg/kg, i.p.) or morphine (10 mg/kg, i.p.), rats were subjected to repeated CPP extinction sessions. A low dose priming injection of MG or morphine produced a reinstatement of the previously extinguished CPP. In the second experiment of this study, a priming injection of morphine (1, 3 and 10 mg/kg, i.p.) dose-dependently reinstated an MG-induced CPP. Likewise, a priming injection of MG (3, 10 and 30 mg/kg, i.p.) was able to dose-dependently reinstate a morphine-induced CPP. The present study demonstrates a cross-reinstatement effect between MG and morphine, thereby suggesting a similar interaction in their rewarding motivational properties. The findings from this study also suggesting that a priming exposure to kratom and an opioid may cause relapse for a previously abused drug.
  19. Mohamed Sofian Z, Harun N, Mahat MM, Nor Hashim NA, Jones SA
    Eur J Pharm Biopharm, 2021 Nov;168:53-61.
    PMID: 34455038 DOI: 10.1016/j.ejpb.2021.08.003
    Transiently associating amines with therapeutic agents through the formation of ion-pairs has been established both in vitro and in vivo as an effective means to systemically direct drug delivery to the lung via the polyamine transport system (PTS). However, there remains a need to better understand the structural traits required for effective PTS uptake of drug ion-pairs. This study aimed to use a structurally related series of amine counterions to investigate how they influenced the stability of theophylline ion-pairs and their active uptake in A549 cells. Using ethylamine (mono-amine), ethylenediamine (di-amine), spermidine (tri-amine) and spermine (tetra-amine) as counterions the ion-pair affinity was shown to increase as the number of protonated amine groups in the counterion structure increased. The mono and diamines generated a single hydrogen bond and the weakest ion-pair affinities (pKFTIR: 1.32 ± 0.04 and 1.43 ± 0.02) whereas the polyamines produced two hydrogen bonds and thus the strongest ion-pair affinities (pKFTIR: 1.93 ± 0.05 and 1.96 ± 0.04). In A549 cells depleted of endogenous polyamines using α-difluoromethylornithine (DFMO), the spermine-theophylline uptake was significantly increased (p 
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