To the Editor—Gamma-hydroxybutyrate (GHB) is a central nervous system depressant with short-term hypnotic and euphoric effects. It is a notorious date rape drug that is extensively abused to enhance sexual activity and pleasure (colloquially known as ‘chemfun’) among men who have sex with men. Gamma-hydroxybutyrate overdose can cause drowsiness, respiratory depression, or coma.1 Gamma-hydroxybutyrate and its pro-drug gamma-butyrolactone are dangerous drugs within the meaning of the Dangerous Drugs Ordinance.2

1,4-Butanediol, an industrial solvent, is converted to GHB by hepatic alcohol dehydrogenase and aldehyde dehydrogenase.3 Generally, its onset of action is 5 to 20 minutes after ingestion with effects lasting for 2 to 3 hours.4 Nonetheless there is inter-individual variability in its metabolism to GHB, mainly due to differences in alcohol dehydrogenase activity.3 Importantly, concurrent ethanol intake inhibits conversion of 1,4-butanediol to GHB.5 With a delayed onset of GHB-related desirable effects, inadvertent overdose may occur in those whose intention was to ingest GHB rather than 1,4-butanediol.3 6

At the time or writing, 1,4-butanediol is not listed as a dangerous drug. Our laboratory confirmed two cases of 1,4-butanediol misuse and poisoning related to ‘chemfun’ or suspected sexual assault. One of the cases had concurrent ethanol consumption. When encountering cases of suspected GHB poisoning, clinicians should be aware of the possibility of 1,4-butanediol ingestion and educate patients in high-risk groups about the dangers of misusing 1,4-butanediol. To prevent GHBrelated crime, poisoning, or death,1 the government should consider classifying 1,4-butanediol as a dangerous drug, given its accessibility and potential for misuse.

Concept or design: All authors.
Acquisition of data: All authors.
Analysis or interpretation of data: All authors.
Drafting of the manuscript: CW Yeung, YK Chong.
Critical revision of the manuscript for important intellectual content: All authors.

All authors had full access to the data, contributed to the study, approved the final version for publication, and take responsibility for its accuracy and integrity.

All authors have disclosed no conflicts of interest.

This letter received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

1. Dufayet L, Bargel S, Bonnet A, et al. Gamma-hydroxybutyrate (GHB), 1,4-butanediol (1,4BD), and gamma-butyrolactone (GBL) intoxication: a state-of-the-art review. Regul Toxicol Pharmacol 2023;142:105435. Crossref

2. Hong Kong e-Legislation, Hong Kong SAR Government. Cap 134 Dangerous Drugs Ordinance. Available from: https://www.elegislation.gov.hk/hk/cap134!en-zh-Hant-HK?INDEX_CS=N. Accessed 5 Feb 2025.

3. Thai D, Dyer JE, Jacob P, Haller CA. Clinical pharmacology of 1,4-butanediol and gamma-hydroxybutyrate after oral 1,4-butanediol administration to healthy volunteers. Clin Pharmacol Ther 2007;81:178-84. Crossref

4. Drug & Chemical Evaluation Section, Diversion Control Division, Drug Enforcement Administration, US Department of Justice. 1,4-Butanediol. 2024. Available from: https://www.deadiversion.usdoj.gov/drug_chem_info/bdo.pdf. Accessed 21 Jun 2024.

5. Poldrugo F, Barker S, Basa M, Mallardi F, Snead OC. Ethanol potentiates the toxic effects of 1,4-butanediol. Alcohol Clin Exp Res 1985;9:493-7. Crossref

6. Stefani M, Roberts DM. 1,4-Butanediol overdose mimicking toxic alcohol exposure. Clin Toxicol (Phila) 2020;58:204-7. Crossref

To the Editor—Ketamine analogues are new psychoactive substances that share the arylcyclohexylamine backbone of ketamine and produce dissociative effects through antagonistic activity at the N-methyl-D-aspartate receptor.1 Ketamine and its analogues have plagued Hong Kong over the last two decades. Our laboratory has identified outbreaks of multiple ketamine analogues in Hong Kong, including 2-oxo-phenylcyclohexylethylamine in 2017,2 2-fluorodeschloroketamine (2F-DCK) and deschloroketamine in 2019,3 and tiletamine in 2019 to 2022 (according to data on file in the Hospital Authority Toxicology Reference Laboratory).

We report identification of a new ketamine analogue, fluoro-2-oxo-phenylcyclohexylethylamine, also known as fluorexetamine (FXE). Recreational use of FXE was first reported in 2018.4 Our laboratory has detected increasing use of FXE in Hong Kong since mid-2023, with FXE now identified in urine samples of 14 patients. Detection of FXE can be difficult since it does not cross-react with bedside ketamine immunoassay and shares common metabolites with 2F-DCK. This may lead to misidentification of FXE metabolites as 2F-DCK metabolites on routine toxicology testing. Clinically, FXE appears to possess similar toxicity to ketamine and 2F-DCK and co-ingestion with other recreational drugs is common, often complicating the clinical presentation.

Effective prevention of the emergence of new psychoactive substances can be achieved through prompt communication and accurate toxicology testing. This approach has been successful in halting the upward trajectory of various ketamine analogues. When encountering patients with clinical features of ketamine abuse but negative immunoassay or urine toxicology results, clinicians are encouraged to submit urine specimens to our laboratory for further testing.

Concept or design: All authors.
Acquisition of data: All authors.
Analysis or interpretation of data: All authors.
Drafting of the manuscript: TM Han, YK Chong.
Critical revision of the manuscript for important intellectual content: All authors.

All authors had full access to the data, contributed to the study, approved the final version for publication, and take responsibility for its accuracy and integrity.

All authors have disclosed no conflicts of interest.

This letter received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

1. Morris H, Wallach J. From PCP to MXE: a comprehensive review of the non-medical use of dissociative drugs. Drug Test Anal 2014;6:614-32. Crossref

2. Chong YK, Tang MH, Chan CL, Li YK, Ching CK, Mak TW. 2-oxo-PCE: ketamine analogue on the streets. Hong Kong Med J 2017;23:665-6. Crossref

3. Li C, Lai CK, Tang MH, Chan CC, Chong YK, Mak TW. Ketamine analogues multiplying in Hong Kong. Hong Kong Med J 2019;25:169. Crossref

4. National Drug Early Warning System. Alert from the NDEWS Web Monitoring Team: online mentions of fluorexetamine. 2022. Available from: https://ndews.org/wordpress/files/2023/04/8.12.22.pdf. Accessed 12 Jul 2024.

To the Editor—Chan et al1 drew our attention to the fact that tuberculosis can be a great mimicker of other conditions when it affects the knee. Conversely the knee may be a site where problems may mimic other disorders. Knee injuries are among the most common disabling conditions that arise from sporting and other accidents or falls. The presence of septic arthritis may overlap or complicate a traumatic knee condition. Septic arthritis by itself may affect the knee, as well as autoimmune-related arthritis. Yet uncommonly, gout and other crystal arthritis may have a similar clinical and radiological presentation.2 Only when urate or calcium pyrophosphate are identified can the diagnosis be confirmed. The title ‘great mimicker’ was originally applied to syphilis, a disease that declined considerably in the last century but that is recently exhibiting a resurgence due to uncontrolled sexually transmitted diseases.3 Syphilis targets virtually every organ and the knee is no exception. In North America, another spirochete infection, Lyme disease, is known to infect people bitten by ticks or in contact with wild animals, and prominent among its symptoms is arthritis, including that of the knee.4 In Hong Kong, we do not have Lyme disease but we should maintain a high index of suspicion in individuals who have visited North America and who present with fever, fatigue and joint pain. The risk is not confined to recent exposures since the disease may be quiescent for months or even years before a flare-up.

The author solely contributed to the concept or design, acquisition of data, analysis or interpretation of data, drafting of the letter, and critical revision of the letter for important intellectual content. The author had full access to the data, contributed to the study, approved the final version for publication, and takes responsibility for its accuracy and integrity.

The author has disclosed no conflict of interest.

This letter received no specific grant from any funding agency in the public, commercial, or not-for profit sectors.

1. Chan HM, Fu H, Chiu KY. Tuberculosis of the knee as a great mimicker of inflammatory arthritis: a case report. Hong Kong Med J 2023;29:548-50. Crossref

2. Yun SY, Choo HJ, Jeong HW, Lee SJ. Comparison of MR findings between patients with septic arthritis and acute gouty arthritis of the knee. J Korean Soc Radiol 2022;83:1071-80. Crossref

3. Peeling RW, Hook EW 3rd. The pathogenesis of syphilis: the great mimicker, revisited. J Pathol 2006;208:224-32. Crossref

4. Arvikar SL, Steere AC. Diagnosis and treatment of Lyme arthritis. Infect Dis Clin North Am 2015;29:269-80. Crossref

To the Editor—We write in response to an article published in November 2023 on digital media that discussed the difficulties faced by local young cancer patients who are receiving oncology treatment.1 We would like to highlight the importance of addressing these challenges and propose solutions to help overcome them.

In 2021, young oncology patients comprised up to 4.1% of all cancer cases in Hong Kong.2 They experience a range of emotional, social, and financial challenges that greatly impact their overall well-being. Neglecting their needs not only strains their relationship with family, but also hampers their ability to effectively cope with the disease. The financial toxicity of cancer treatment, which includes the expenses, indirect costs and lost income associated with cancer treatment, further exacerbates these challenges.3 4

To address these issues effectively it is essential to provide services specifically designed for young cancer patients according to their stage of development. They are at high risk of psychosocial problems and should be prioritised for early integration into palliative care services to improve their quality of life and that of their family.5 Mental health professionals and support groups should be widely available for psychological support. Some medical allowances and social services are provided only for the older adults. Medical-social collaboration and educational resources could improve access by young adults to community support. Additionally, implementing targeted financial assistance programmes and providing employment support will help alleviate the financial burden. It is crucial to recognise and address the obstacles faced by young cancer patients.

All authors contributed to the concept or design, acquisition of data, or interpretation of data, drafting of the letter, and critical revision of the letter for important intellectual content. All authors had full access to the data, contributed to the study, approved the final version for publication, and take responsibility for its accuracy and integrity.

All authors have disclosed no conflicts of interest.

This letter received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

1. HK01. Hong Kong young cancer patients established a mutual aid platform to help themselves as existing cancer support is mostly targeted at the middle-aged and older adults. [in Chinese]. 2023 November 22. Available from: https://www.hk01.com/article/957641?utm_source=01appshare&utm_medium=referral. Accessed 26 Nov 2023.

2. Hong Kong Cancer Registry, Hospital Authority, Hong Kong SAR Government. Overview of Hong Kong Cancer Statistics of 2021. Available from: https://www3.ha.org.hk/cancereg/default.asp. Accessed 28 Nov 2023.

3. Evan EE, Zeltzer LK. Psychosocial dimensions of cancer in adolescents and young adults. Cancer 2006;107(7 Suppl):1663-71. Crossref

4. Geue K, Götze H, Friedrich M, et al. Perceived social support and associations with health-related quality of life in young versus older adult patients with haematological malignancies. Health Qual Life Outcomes 2019;17:145. Crossref

5. Zimmermann C, Swami N, Krzyzanowska M, et al. Early palliative care for patients with advanced cancer: a cluster-randomised controlled trial. Lancet 2014;383:1721-30. Crossref

To the Editor—There was a local blog report in Hong Kong of a 5-year-old girl who experienced out-of-hospital cardiac arrest (OHCA) with return of spontaneous circulation (ROSC) after 31 minutes and was discharged with an implantable cardioverter defibrillator.1 However, ROSC within 30 minutes is usually required for a favourable outcome.2 3

We performed a literature search to determine the longest time to ROSC and survival rates of OHCA in children (Table). Out-of-hospital cardiac arrest in children has a poor prognosis and prolonged in-hospital resuscitation beyond 30 minutes does not improve survival.3 Predictors of survival to discharge include witnessed arrest (P=0.012), delivery of bystander cardiopulmonary resuscitation (P=0.003), and duration of resuscitation (P=0.028). However, none who received more than 30 minutes of in-hospital resuscitation survived.4 A prospective study found that no patients who required >2 doses of adrenaline or in-hospital resuscitation for longer than 20 minutes survived to discharge.5 However, it is possible that ROSC beyond 30 minutes has not been reported, or that this case is an exception.

Evidence suggests that either death or a poor outcome is inevitable if OHCA occurs more than 30 minutes from the nearest healthcare facility or the resuscitation exceeds 30 minutes.6 7 A 2017 study reported that the survival rate to discharge in Hong Kong was only 2.3%, which was considerably lower than the global survival rate in adults (8.8%).8 9 As OHCA in children has not been evaluated in Hong Kong until 2018,3 and prospective evaluation of OHCA in children has not yet been conducted, we concur with Wu10 who suggested the establishment of an OHCA registry.

Many parents and family members who are present during a resuscitation attempt would want to be in attendance if their child were likely to die, and this experience can help with later grieving without impacting on the resuscitation process. If appropriate, family-centred care should be practised and parents should be involved in the decision-making process.6 As paediatricians, although our patient is the child, his/her family members are also important—after all, if the child passes away, it is the family who must shoulder the lifelong emotional burden.

In summary, OHCA in children has a poor prognosis and prolonged resuscitation does not improve survival or outcome.

All authors contributed to the drafting of the letter and critical revision for important intellectual content. All authors approved the final version for publication and take responsibility for its accuracy and integrity.

As an editor of the journal, KL Hon was not involved in the peer review process. Other authors have disclosed no conflicts of interest.

This letter received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

1. Philip. 死去31分鐘的女兒 [in Chinese]. Available from: https://todecidenow.wordpress.com/2021/01/31/死去31分鐘的女兒！/. Accessed 24 Jul 2023.

2. Hon KL, Tse TT, Au CC, et al. Brain death in children: a retrospective review of patients at a paediatric intensive care unit. Hong Kong Med J 2020;26:120-6. Crossref

3. Law AK, Ng MH, Hon KL, Graham CA. Out-of-hospital cardiac arrest in the pediatric population in Hong Kong: a 10-year review at a university hospital. Pediatr Emerg Care 2018;34:179-84. Crossref

4. Tham LP, Chan I. Paediatric out-of-hospital cardiac arrests: epidemiology and outcome. Singapore Med J 2005;46:289-96.

5. Schindler MB, Bohn D, Cox PN, et al. Outcome of out-of-hospital cardiac or respiratory arrest in children. N Engl J Med 1996;335:1473-9. Crossref

6. American College of Surgeons Committee on Trauma; American College of Emergency Physicians Pediatric Emergency Medicine Committee; National Association of EMS Physicians; American Academy of Pediatrics Committee on Pediatric Emergency Medicine; Fallat ME. Withholding or termination of resuscitation in pediatric out-of-hospital traumatic cardiopulmonary arrest. Pediatrics 2014;133:e1104-16. Crossref

7. American Heart Association. Highlights of the 2020 American Heart Association Guidelines for CPR and ECC. 2020. Available from: https://cpr.heart.org/-/media/cpr-files/cpr-guidelines-files/highlights/hghlghts_2020_ecc_guidelines_english.pdf. Accessed 3 Apr 2021.

8. Fan KL, Leung LP, Siu YC. Out-of-hospital cardiac arrest in Hong Kong: a territory-wide study. Hong Kong Med J 2017;23:48-53. Crossref

9. Yan S, Gan Y, Jiang N, et al. The global survival rate among adult out-of-hospital cardiac arrest patients who received cardiopulmonary resuscitation: a systematic review and meta-analysis. Crit Care 2020;24:61. Crossref

10. Wu WY. Out-of-hospital cardiac arrest: the importance of a registry. Hong Kong Med J 2019;25:176-7. Crossref