The Role of Pharmacogenomics in Opioid Prescribing.

OPINION STATEMENT: Pharmacogenomics is increasingly important to guide objective, safe, and effective individualised prescribing. Personalised prescribing has revolutionised treatments in the past decade, allowing clinicians to maximise drug efficacy and minimise adverse effects based on a person's genetic profile. Opioids, the gold standard for cancer pain relief, are among the commonest medications prescribed in palliative care practice. This narrative review examines the literature surrounding opioid pharmacogenomics and its applicability to the palliative care cancer population. There is currently limited intersection between the fields of palliative care and pharmacogenomics, but growing evidence presents a need to build linkages between the two disciplines. Pharmacogenomic evidence guiding opioid prescribing is currently available for codeine and tramadol, which relates to CYP2D6 gene variants. However, these medications are prescribed less commonly for pain in palliative care. Research is accelerating with other opioids, where oxycodone (CYP2D6) and methadone (CYP2B6, ABCB1) already have moderate evidence of an association in terms of drug metabolism and downstream analgesic response and side effects. OPRM1 and COMT are receiving increasing attention and have implications for all opioids, with changes in opioid dosage requirements observed but they have not yet been studied widely enough to be considered clinically actionable. Current evidence indicates that incorporation of pharmacogenomic testing into opioid prescribing practice should focus on the CYP2D6 gene and its actionable variants. Although opioid pharmacogenomic tests are not widely used in clinical practice, the progressively reducing costs and rapid turnover means greater accessibility and affordability to patients, and thus, clinicians will be increasingly asked to provide guidance in this area. The upsurge in pharmacogenomic research will likely discover more actionable gene variants to expand international guidelines to impact opioid prescribing. This rapidly expanding area requires consideration and monitoring by clinicians in order for key findings with clinical implications to be accessible, meaningfully interpretable and communicated.

Managing postoperative pain in adult outpatients: a systematic review and meta-analysis comparing codeine with NSAIDs.

BACKGROUND: Analgesics that contain codeine are commonly prescribed for postoperative pain, but it is unclear how they compare with nonopioid alternatives. We sought to compare the effectiveness of codeine and nonsteroidal anti-inflammatory drugs (NSAIDs) for adults who underwent outpatient surgery. METHODS: We conducted a systematic review and meta-analysis of randomized controlled trials comparing codeine and NSAIDs for postoperative pain in outpatient surgery. We searched MEDLINE and Embase from inception to October 2019 for eligible studies. Our primary outcome was the patient pain score, converted to a standard 10-point intensity scale. Our secondary outcomes were patient-reported global assessments and adverse effects. We used random-effects models and grading of recommendations assessment, development and evaluation (GRADE) to assess the quality of evidence. RESULTS: Forty studies, including 102 trial arms and 5116 patients, met inclusion criteria. The studies had low risk of bias and low-to-moderate heterogeneity. Compared with codeine, NSAIDs were associated with better pain scores at 6 hours (weighted mean difference [WMD] 0.93 points, 95% confidence interval [CI] 0.71 to 1.15) and at 12 hours (WMD 0.79, 95% CI 0.38 to 1.19). Stronger NSAID superiority at 6 hours was observed among trials where acetaminophen was coadministered at equivalent doses between groups (WMD 1.18, 95% CI 0.87 to 1.48). NSAIDs were associated with better global assessments at 6 hours (WMD -0.88, 95% CI -1.04 to -0.72) and at 24 hours (WMD -0.67, 95% CI -0.95 to -0.40), and were associated with fewer adverse effects, including bleeding events. INTERPRETATION: We found that adult outpatients report better pain scores, better global assessments and fewer adverse effects when their postoperative pain is treated with NSAIDs than with codeine. Clinicians across all specialties can use this information to improve both pain management and opioid stewardship.

Analgesic effect of oral ibuprofen 400, 600, and 800 mg; paracetamol 500 and 1000 mg; and paracetamol 1000 mg plus 60 mg codeine in acute postoperative pain: a single-dose, randomized, placebo-controlled, and double-blind study.

PURPOSE: Effect size estimates of analgesic drugs can be misleading. Ibuprofen (400 mg, 600 mg, 800 mg), paracetamol (1000 mg, 500 mg), paracetamol 1000 mg/codeine 60 mg, and placebo were investigated to establish the multidimensional pharmacodynamic profiles of each drug on acute pain with calculated effect size estimates. METHODS: A randomized, double-blind, single-dose, placebo-controlled, parallel-group, single-centre, outpatient, and single-dose study used 350 patients (mean age 25 year, range 18 to 30 years) of homogenous ethnicity after third molar surgery. Primary outcome was sum pain intensity over 6 h. Secondary outcomes were time to analgesic onset, duration of analgesia, time to rescue drug intake, number of patients taking rescue drug, sum pain intensity difference, maximum pain intensity difference, time to maximum pain intensity difference, number needed to treat values, adverse effects, overall drug assessment as patient-reported outcome measure (PROM), and the effect size estimates NNT and NNTp. RESULTS: Ibuprofen doses above 400 mg do not significantly increase analgesic effect. Paracetamol has a very flat analgesic dose-response profile. Paracetamol 1000/codeine 60 mg gives similar analgesia as ibuprofen from 400 mg, but has a shorter time to analgesic onset. Active drugs show no significant difference in maximal analgesic effect. Other secondary outcomes support these findings. The frequencies of adverse effects were low, mild to moderate in all active groups. NNT and NTTp values did not coincide well with PROMs. CONCLUSION: Ibuprofen doses above 400 mg for acute pain offer limited analgesic gain. Paracetamol 1000 mg/codeine 60 mg is comparable to ibuprofen doses from 400 mg. Calculated effect size estimates and PROM in our study seem not to relate well as clinical analgesic efficacy estimators. TRIAL REGISTRATION: NCT00699114.

Relationship of perioperative anaphylaxis to neuromuscular blocking agents, obesity, and pholcodine consumption: a case-control study.

BACKGROUND: The observation that patients presenting for bariatric surgery had a high incidence of neuromuscular blocking agent (NMBA) anaphylaxis prompted this restricted case-control study to test the hypothesis that obesity is a risk factor for NMBA anaphylaxis, independent of differences in pholcodine consumption. METHODS: We compared 145 patients diagnosed with intraoperative NMBA anaphylaxis in Western Australia between 2012 and 2020 with 61 patients with cefazolin anaphylaxis with respect to BMI grade, history of pholcodine consumption, sex, age, comorbid disease, and NMBA type and dose. Confounding was assessed by stratification and binomial logistic regression. RESULTS: Obesity (odds ratio [OR]=2.96, χ2=11.7, P=0.001), 'definite' pholcodine consumption (OR=14.0, χ2=2.6, P<0.001), and female sex (OR=2.70, χ2=9.61, P=0.002) were statistically significant risk factors for NMBA anaphylaxis on univariate analysis. The risk of NMBA anaphylaxis increased with BMI grade. Confounding analysis indicated that both obesity and pholcodine consumption remained important risk factors after correction for confounding, but that sex did not. The relative rate of rocuronium anaphylaxis was estimated to be 3.0 times that of vecuronium using controls as an estimate of market share, and the risk of NMBA anaphylaxis in patients presenting for bariatric surgery was 8.8 times the expected rate (74.9 vs 8.5 per 100 000 anaesthetic procedures). CONCLUSIONS: Obesity is a risk factor for NMBA anaphylaxis, the risk increasing with BMI grade. Pholcodine consumption is also a risk factor, and this is consistent with the pholcodine hypothesis. Rocuronium use is associated with an increased risk of anaphylaxis compared with vecuronium in this population.

Should Codeine Still be Considered a WHO Essential Medicine?

Codeine continues to be widely used as an analgesic, antidiarrhoeal and antitussive agent. Its analgesic effect depends on its biotransformation to morphine, a strong opioid. The highly variable biotransformation of codeine to morphine, catalysed by CYP2D6, underlies the pronounced interindividual variability of its analgesic response. Randomized controlled trials have demonstrated that codeine administered alone has the poorest analgesic effect among all commonly used analgesics in acute postoperative pain. Moreover, it is highly unlikely that the low dose of codeine contributes to the pain-relieving effect of the non-opioid component in combination analgesic products. In addition, there is a lack of reliable clinical evidence to support the use of codeine as an antitussive in acute or chronic cough. Codeine use, through its active metabolite morphine, has the potential to lead to abuse and dependence. The World Health Organization (WHO) removed codeine from the essential medicines list for children in 2011. Based on the available information in the scientific literature on the efficacy and safety of codeine, the WHO should seriously consider removing it also from the list of essential medicines for adults, which would be a strong signal for all health professionals to prescribe and dispense codeine with the utmost caution.

Identification of factors influencing tampering of codeine-containing medicines in England: a qualitative study.

BACKGROUND: Tampering of psychoactive medicines presents challenges to regulation and public health. However, little is currently known about what influences the decisions to treat codeine-containing medicines (CCM) with cold water extraction (CWE) from the perspective of individuals employing these techniques. The article identifies factors influencing utilisation of CWE to separate codeine from compounded analgesics, such as paracetamol and ibuprofen, found in CCM. METHODS: Purposive sampling of 27 participants residing in England who took part in a qualitative interview. Of these, 14 individuals (11 males and 3 females) reported tampering of psychoactive medicines, and the relevant transcripts were included in the analyses for the study. Participants were recruited from one addiction treatment service and from an online survey. The mean age of the participants was 31.5 years (range = 18-42 years). Qualitative data analysis followed the processes of iterative categorization (IC). The codes 'harm reduction', 'information sources' and 'changes on the drug markets' were grouped and summarised. The coding of the data was done in a Microsoft® Word document. RESULTS: Two groups of participants were identified in the data analysis: (i) individuals who used CCM (n = 5), and (ii) individuals who used CCM and heroin (n = 9). Participants in both groups used CWE due to concerns of paracetamol overdose from the use of excessive dosages of CCM. For both of them, information obtained from the internet encouraged the use of CWE. Participants using CCM described how the many steps involved in conducting CWE, including sourcing codeine boxes from pharmacies (over the counter), presented a barrier against using CWE. Participants using CCM and heroin explained how reduced availability in the local heroin supply influenced utilisation of CWE techniques to maintain their use of opioids and avoid withdrawal. Withdrawal symptoms and cravings outweighed the concerns about the quality of the extracted codeine mixtures in this participant group, especially the ability of CWE to remove paracetamol and tablet fillers. CONCLUSIONS: Utilisation of CWE of codeine was influenced by several factors including drug market supply, the availability of detailed information on the internet about CWE and restrictions on codeine sourcing in pharmacies. Risks identified with CWE include consumption of unknown doses of paracetamol if the CWE techniques are not used correctly. Attempts at extracting codeine from CCM should be considered in risk assessments of opioid medicines.

A Study of Opiate, Opiate Metabolites and Antihistamines in Urine after Consumption of Cold Syrups by LC-MS/MS.

Studying the origin of opiate and/or opiate metabolites in individual urine specimens after consumption of cold syrups is vital for patients, doctors, and law enforcement. A rapid liquid chromatography-tandem mass spectrometry method using "dilute-and-shoot" analysis without the need for extraction, hydrolysis and/or derivatization has been developed and validated. The approach provides linear ranges of 2.5-1000 ng mL-1 for 6-acetylmorphine, codeine, chlorpheniramine, and carbinoxamine, 2.5-800 ng mL-1 for morphine and morphine-3-ß-d-glucuronide, and 2.5-600 ng mL-1 for morphine-6-ß-d-glucuronide and codeine-6-ß-d-glucuronide, with excellent correlation coefficients (R2 > 0.995) and matrix effects (< 5%). Urine samples collected from the ten participants orally administered cold syrups were analyzed. The results concluded that participants consuming codeine-containing cold syrups did not routinely pass urine tests for opiates, and their morphine-codeine concentration ratios (M/C) were not always < 1. In addition, the distribution map of the clinical total concentration of the sum of morphine and codeine against the antihistamines (chlorpheniramine or carbinoxamine) were plotted for discrimination of people who used cold syrups. The 15 real cases have been studied by using M/C rule, cutoff value, and distribution map, further revealing a potential approach to determine opiate metabolite in urine originating from cold syrups.

CYP2D6-guided opioid therapy improves pain control in CYP2D6 intermediate and poor metabolizers: a pragmatic clinical trial.

PURPOSE: CYP2D6 bioactivates codeine and tramadol, with intermediate and poor metabolizers (IMs and PMs) expected to have impaired analgesia. This pragmatic proof-of-concept trial tested the effects of CYP2D6-guided opioid prescribing on pain control. METHODS: Participants with chronic pain (94% on an opioid) from seven clinics were enrolled into CYP2D6-guided (n = 235) or usual care (n = 135) arms using a cluster design. CYP2D6 phenotypes were assigned based on genotype and CYP2D6 inhibitor use, with recommendations for opioid prescribing made in the CYP2D6-guided arm. Pain was assessed at baseline and 3 months using PROMIS® measures. RESULTS: On stepwise multiple linear regression, the primary outcome of composite pain intensity (composite of current pain and worst and average pain in the past week) among IM/PMs initially prescribed tramadol/codeine (n = 45) had greater improvement in the CYP2D6-guided versus usual care arm (-1.01 ± 1.59 vs. -0.40 ± 1.20; adj P = 0.016); 24% of CYP2D6-guided versus 0% of usual care participants reported ≥30% (clinically meaningful) reduction in the composite outcome. In contrast, among normal metabolizers prescribed tramadol or codeine at baseline, there was no difference in the change in composite pain intensity at 3 months between CYP2D6-guided (-0.61 ± 1.39) and usual care (-0.54 ± 1.69) groups (adj P = 0.540). CONCLUSION: These data support the potential benefits of CYP2D6-guided pain management.

Oral Paracetamol Versus Combination Oral Analgesics for Acute Musculoskeletal Injuries.

STUDY OBJECTIVE: We compare paracetamol with a combination of paracetamol, ibuprofen, and codeine for pain relief in acute minor musculoskeletal injuries. METHODS: This was a prospective, double-blind, randomized, active-controlled, parallel-arm study at an urban tertiary hospital emergency department. Participants were aged 18 to 65 years and had acute (<48 hours) closed limb or trunk injuries with moderate pain (greater than 3/10). A single dose of 1 g of paracetamol, 400 mg of ibuprofen, and 60 mg of codeine was compared with a single dose of 1 g of paracetamol, placebo ibuprofen, and placebo codeine. The minimum detectable difference in pain was taken as 1.3. RESULTS: Baseline characteristics and pain were similar. There were clinically detectable reductions in pain at rest at 60 minutes for paracetamol: -1.6; 95% confidence interval (CI) -2.2 to -1.1); n=59 and the combination -2.0; 95% CI -2.5 to -1; n=59; difference -0.4; 95% CI -1.1 to 0.29; P=.26. At 120 minutes, the reduction in pain was -2.4; 95% CI -3.2 to -1.6 for paracetamol (n=30) and -2.9; 95% CI -3.7 to -2.2 for the combination (n=35); difference -0.5; 95% CI -1.6 to 0.5; P=.32. Rescue analgesia was required by 4 of 59 patients in the paracetamol group and 5 of 60 in the combination group (P>.99). More participants in the combination group had adverse events: 14 of 60 versus 5 of 59 in the paracetamol group, relative risk 2.8; 95% CI 1.1 to 7.2. No adverse events were serious. CONCLUSION: Combining oral paracetamol, ibuprofen, and codeine as the initial treatment for pain associated with acute musculoskeletal injuries was not superior to paracetamol alone for pain reduction at 60 minutes or need for rescue analgesia, with more adverse events in the combination group.

Likelihood of depressive symptoms in US older adults by prescribed opioid potency: National Health and Nutrition Examination Survey 2005-2013.

OBJECTIVES: To investigate the relationships between depressive symptoms and opioid potency among adults aged 50 years and older reporting use of one or more prescription opioids in the past 30 days. MATERIALS/DESIGN: Adjusted multiple linear regression models were conducted with 2005-2013 files from a secondary cross-sectional dataset, the National Health and Nutrition Examination Survey (NHANES). Respondents were community-dwelling, noninstitutionalized adults 50 years or older (n = 1036). Predictor variables included a positive screen for minor depression symptoms (Patient Health Questionnaire [PHQ-9] score greater than or equal to 5 and less than or equal to 9), moderate depression symptoms (PHQ-9 greater than or equal to 10 and less than or equal to 14), and severe depression symptoms (PHQ-9 greater than or equal to 15). Criterion variables included weaker-than-morphine analgesics (eg, codeine and tramadol) and morphine-equivalent opioids (eg, morphine and hydrocodone), which served as the reference category, as well as stronger-than-morphine opioid analgesics (eg, fentanyl and oxycodone). RESULTS: Prevalence rates for symptoms of minor depression, moderate depression, and severe depression were n = 236 (22.8%), n = 135 (13.0%), and n = 122 (11.8%), respectively. Severe depression was significantly associated with high-potency opioid use (odds ratio [OR]: 2.27; confidence interval [CI], 1.16-4.46). In post hoc tests, severe depression remained significantly associated with high-potency opioid use only among respondents without arthritis (OR: 5.80; CI, 1.59-21.13). CONCLUSIONS: Compared with older adults without depressive symptoms, older adults with severe depressive symptoms are more likely to be taking high-potency opioid medications. Future prescription opioid medication research should prioritize investigations among older adults with pain-related diagnoses, other than arthritis, reporting preexisting or new symptoms of severe depression.

A European multicentre drug utilisation study of the impact of regulatory measures on prescribing of codeine for pain in children.

PURPOSE: In June 2013, following recommendations from the World Health Organization (WHO) and Food and Drug Administration (FDA), the European Medicines Agency agreed updates to the codeine product information regarding use for pain in children younger than 12 years and children undergoing tonsillectomy or adenoidectomy (TA) for obstructive sleep apnoea. This study was conducted to (a) assess effectiveness of these measures on codeine prescribing in the "real-world" setting and (b) test feasibility of a study using a common protocol by regulators with access to databases. METHODS: The study was performed using BIFAP (Spain), CPRD (UK), and IMS® Disease Analyzer (France and Germany) databases. Prescribers included general practitioners (GPs) (France and UK), GPs and paediatricians together (Spain), and GPs, paediatricians, and ear, nose, and throat (ENT) specialists separately (Germany). Between January 2010 and June 2015, prevalence of codeine prescribing was obtained every 6 months, and a time series analysis (joinpoint) was performed. Codeine prescribing within ±30 days of TA was also identified. Furthermore, doses, durations, and prior prescribing of other analgesics were investigated. RESULTS: Over the 5-year period, codeine prescribing decreased in children younger than 12 years (by 84% in France and Spain, 44% in GP practices in Germany, and 33% in the United Kingdom). The temporal pattern was compatible with the regulatory intervention in France and the United Kingdom, whereas a decrease throughout the study period was seen in Germany and Spain. Decreased prescribing associated with TA was suggested in ENT practices in Germany. CONCLUSIONS: Codeine prescribing for children decreased in line with introduced regulatory measures. Multidatabase studies assessing impact of measures by EU regulators are feasible.

Adult and infant pharmacokinetic profiling of dihydrocodeine using physiologically based pharmacokinetic modeling.

We previously analysed the serum concentrations of dihydrocodeine in a 1-month-old infant with respiratory depression after being prescribed dihydrocodeine phosphate 2.0 mg/day divided t.i.d. for 2 days. The purpose was to develop a full physiologically based pharmacokinetic (PBPK) model that could account for these and other drug monitoring results. Based on experiments in Caco-2 cell monolayers, the effective permeability of dihydrocodeine in human jejunum was established as 1.28 × 10-4 cm/s. The in vitro Vmax /Km values for dihydrocodeine demethylation mediated by recombinant cytochrome P450 2D6 and 3A4 were 0.19 and 0.066 µl/min/pmol, respectively, and for dihydrocodeine 6-O-glucuronidation mediated by recombinant UGT2B4 and 2B7, the Vmax /Km values were 0.14 and 0.22 µl/min/mg protein, respectively. Renal clearance was calculated as 5.37 L/h on the total clearance value multiplied by the fraction recovered in urine. The reported plasma concentration-time profiles of dihydrocodeine after intravenous administration in healthy volunteers were used to adjust the tissue partitioning ratios. The developed model simulated the pharmacokinetic profiles of dihydrocodeine after single and multiple oral administrations reasonably well in the same population. Subsequently, the validated model was used to simulate pharmacokinetic profiles for five pediatric cases, including the 1-month-old Japanese boy and a 14-year-old Japanese girl who took an overdose of dihydrocodeine phosphate (37 mg). The simulated pharmacokinetic profiles for five virtual pediatric subjects matching the age, gender, and P450 2D6 phenotype of each case approximately reflected the observed values. These results suggested that our dihydrocodeine PBPK model reproduced the results of clinical cases reasonably well for subjects.

Combating opioid addiction and abuse-2 ways to effectively intervene in the cycle of addiction through pharmacogenomics.

OBJECTIVES: The objectives of this commentary are to: (1) briefly describe the ongoing challenges of addressing opioid abuse, (2) examine codeine metabolism in terms of pharmacogenomics, (3) describe 2 points of patient contact where pharmacogenomics can be implemented to determine the appropriateness of opioid therapy, and (4) briefly explore the value of pharmacogenomics in opioid-abuse and dependency research. SUMMARY: Opioid abuse is one of the most significant medical, social, and economic threats facing our country today. Yet for some patients, opioids are the only effective treatment option in achieving pain relief. Differentiating patients who are susceptible to abuse and addiction from those who are not has been absent in standard statistics-based medication prescribing. Pharmacogenomics (PGX) is a burgeoning science that examines how gene variations (variants) influence drug metabolism. With an estimated 23% of the U.S. population unable to properly metabolize codeine and related analogs, PGX could play an immediate role in the management of opioid therapy if applied (1) as part of regular pre-operative screening assessments and (2) prior to or in conjunction with pain-management referral. CONCLUSION: Using PGX to identify patients who should not begin or continue treatment with opioids because of abnormal metabolic pathways could (1) reduce the number of opioid prescriptions written; (2) reduce related costs; (3) guide more patient-centric, pain-management treatment plans, away from opioids as necessary; and (4) reduce the potential for opioid abuse and addiction.

The Peripheral Versus Central Antinociception of a Novel Opioid Agonist: Acute Inflammatory Pain in Rats.

Opioid analgesics devoid of central side effects are unmet medical need in the treatment of acute pain (e.g. post-operative pain). Recently, we have reported on 14-O-methylmorphine-6-O-sulfate (14-O-MeM6SU), a novel opioid agonist of high efficacy producing peripheral antinociception in subchronic inflammatory pain in certain doses. The present study focused on the antinociceptive effect of 14-O-MeM6SU compared to morphine in formalin test of an early/acute (Phase I) and late/tonic (Phase II) pain phases. Subcutaneous 14-O-MeM6SU (253-1012 nmol/kg) and morphine (3884-31075 nmol/kg) dose dependently reduced the pain behaviors of both phases. Co-administered naloxone methiodide (NAL-M), a peripherally acting opioid antagonist, abolished the antinociceptive effect of 506 nmol/kg 14-O-MeM6SU. On the other hand, the effects of 14-O-MeM6SU (1012 nmol/kg) and morphine (15538 nmol/kg) were only partially affected by NAL-M, indicating the contribution of CNS to antinociception. Locally injected test compounds into formalin treated paws caused antinociception in both phases. Locally effective doses of test compounds were also injected into contralateral paws. Morphine showed effects in both phases, 14-O-MeM6SU in certain doses failed to produce antinociception in either phase. A NAL-M reversible systemic dose of 14-O-MeM6SU and the lowest systemic effective dose of morphine were evaluated for their sedative effects following isoflurane-induced sleeping (righting reflex). In contrast to morphine, 14-O-MeM6SU in certain antinociceptive doses showed no impact on sleeping time. These data highlight that high efficacy opioids of limited CNS penetration in certain doses mitigate somatic and inflammatory pain by targeting MOR at the periphery.

Dihydrocodeine Overdoses in a Neonate and in a 14-year-old Girl Who Were Both Genotyped as Cytochrome P450 2D6*1/*10-*36: Comparing Developmental Ages and Drug Monitoring Data With the Results of Pharmacokinetic Modeling.

A high activity of cytochrome P450 2D6 (CYP2D6) reportedly leads to toxicity of dihydrocodeine/codeine by increasing toxic potential of their metabolite dihydromorphine/morphine, which are further metabolized to highly active dihydromorphine 6-O-glucuronide and the less active morphine 3-O-glucorinide but rapidly excreted into urine as water-soluble forms. A case of acute respiratory depression after administration of prescribed dihydrocodeine phosphate (2.0 mg/d divided twice a day for 2 days) to a 1-month-old baby boy genotyped as CYP2D6*1/*10-*36 is described. The case is compared with that of a 14-year-old girl, also genotyped as CYP2D6*1/*10-*36, presenting in an agitated state after an overdose (37 mg) of dihydrocodeine phosphate taken as simultaneous ingestion of multiple over-the-counter tablets. In contrast to the rapid clearance of dihydrocodeine from blood in the 14-year-old girl (apparent half-life of 3 hours), the 1-month-old baby boy still had high serum concentrations of dihydrocodeine (400 nmol/L) and dihydromorphine (1.9 nmol/L) 21 hours after the last oral administration of dihydrocodeine-containing cough mixture. The rapid clearance in the 14-year-old girl was mainly attributed to dihydrocodeine glucuronidation and partly attributed to dihydromorphine formation, as determined by liquid chromatography-tandem mass spectrometry analyses. However, the conjugation ratios of dihydrocodeine and dihydromorphine in the neonate were low in comparison with those in the 14-year-old girl and with those measured in 3-, 6-, and 13-year-old control subjects, resulting from the poorly developed glucuronidation potential of the neonate. The current observations suggest that the CYP2D6*1/*10-*36 genotype seen in the 2 Japanese patients may not significantly contribute to the likelihood of dihydrocodeine overdose but highlight the importance of considering age when prescribing dihydrocodeine.

Purchasing Over The Counter (OTC) Medicinal Products Containing Codeine - Easy Access, Advertising, Misuse and Perceptions of Medicinal Risk.

PURPOSE: Codeine containing medicines can carry a number of health risks associated with the increase in reported misuse and dependence, however they are still readily available over the counter (OTC) in many countries. The aim of this novel study was to report on the results of a survey of customers purchasing OTC codeine containing medicinal products at pharmacies in Ireland, South Africa and England; exploring use, sources of knowledge and perception of risks. METHODS: The study design was an exploratory cross sectional survey. It involved a customer self-administered questionnaire at the point of purchase (n=1230).  Relationships between categorical variables were analysed using Pearson chi-square for bivariate analysis. Continuous scale variables were analysed using one way analysis of variance. RESULTS: In Ireland 6% stated they purchased codeine containing products weekly, in South Africa 13% and in England 16%. In Ireland and England women are more likely to view codeine containing products as harmful. In England older adults are more likely to perceive codeine containing products as harmful. A higher proportion of customers in South Africa opposed restricting codeine containing products to prescription only when compared with people in Ireland and England. CONCLUSIONS: Codeine containing products are widely purchased and used in all three jurisdictions. Whilst the majority of customers appear to have some awareness and knowledge of risks, it does not materially impact on their purchasing behaviour with a substantial minority purchasing/using such products on a weekly basis. This regularity of purchase whilst indicative of the popularity of such products, may also be a potential indicator of misuse. Future research is needed in relation to cultural and gendered differences and targeted information giving and harm reduction initiatives for safe usage of these medicinal products.

Comparison of Clinical Efficacies of Preoperatively Initiated Naproxen Sodium-Codeine Phosphate in Combination, Diclofenac Potassium, and Benzydamine Hydrochloride for Pain, Edema, and Trismus After Extraction of Impacted Lower Third Molar: A Randomized Double-Blind Study.

PURPOSE: The aim of this study was to compare the clinical efficacies of naproxen sodium-codeine phosphate in combination, benzydamine hydrochloride, and diclofenac potassium for pain, edema, and trismus after lower third molar extraction. MATERIALS AND METHODS: Ninety healthy volunteers in whom impacted third molar extraction was indicated were randomly distributed into 3 groups. One hour before the tooth-extraction process, patients were administered one of the following drugs: naproxen sodium, 550 mg, and codeine phosphate, 30 mg, in a tablet; diclofenac potassium, 50 mg, in a coated pill; or benzydamine hydrochloride, 50 mg, in a coated pill. Pain assessment was conducted via a visual analog scale; edema assessment, by measuring the distances between predetermined facial landmarks; and trismus assessment, by measuring interincisal distance. Regarding rescue analgesics (paracetamol, 500 mg), the number and time of use by patients were recorded. RESULTS: Naproxen sodium-codeine phosphate was more effective for pain, edema, and trismus than diclofenac potassium and benzydamine hydrochloride (P < .05). Benzydamine hydrochloride yielded similar clinical responses to diclofenac potassium (P > .05). No drug-related side effects were observed. CONCLUSIONS: Naproxen sodium-codeine phosphate constitutes the drug of choice after the extraction of a patient's impacted lower third molar. Benzydamine hydrochloride has similar efficacy to diclofenac potassium, and it can be used as a nonsteroidal anti-inflammatory analgesic drug.

Metoclopramide and Diphenhydramine: A Randomized Controlled Trial of a Treatment for Headache in Pregnancy when Acetaminophen Alone Is Ineffective (MAD Headache Study).

OBJECTIVE: We investigated whether metoclopramide administered with diphenhydramine (MAD) relieves headache in pregnant women when acetaminophen alone is ineffective, using codeine for comparison. STUDY DESIGN: Normotensive pregnant women in the second or third trimester were randomized to MAD intravenously (10 mg and 25 mg, respectively) or codeine orally (30 mg) for headache after 650 to 1,000 mg of acetaminophen failed to relieve their headaches. Headache severity (pain score 0-10) was noted at intervals over 24 hours. The primary outcome was reduction in pain score 6 hours after medication administration. A sample size calculation of 35 patients per group was based on estimated reduction in headache pain score by at least two points, with an α of 0.05 and a power of 80%. RESULTS: No difference was seen in the primary outcome. MAD pain scores were lower at 30 minutes (3 ± 2.8 versus 5.8 ± 2.3, p < 0.001), 1 hour (2.2 ± 2.3 vs. 4.1 ± 3; p < 0.01), and 12 hours (1.3 ± 2.5 vs. 2.7 ± 3; p < 0.05), but not at 6 hours. Time to perceived headache relief was shorter for MAD than for codeine (20.2 ± 13.4 vs. 62.4 ± 62.2 minutes; p < 0.001). More patients in the MAD group reported full headache relief within 24 hours (76.5 vs. 37.5%; p < 0.01). CONCLUSION: MAD effectively relieves headaches in pregnant women when acetaminophen fails.

Efficacy of ibuprofen and codeine + paracetamol to reduce immediate bleaching sensitivity caused by in-office tooth bleaching: A randomized, controlled, double-blind clinical trial.

PURPOSE: To evaluate (1) the efficacy of Ibuprofen and codeine + paracetamol to control immediate bleaching sensitivity caused by in-office tooth bleaching performed with 35% hydrogen peroxide, and (2) tooth shade change caused by 35% hydrogen peroxide. METHODS: In this randomized, controlled and double blind clinical trial, 60 volunteers were divided into three treatment groups: 400 mg placebo (PL)(n=20), 400 mg ibuprofen (IB)(n=20), or 30 mg codeine + 500 mg paracetamol (CP)(n=20). The volunteers were submitted to two bleaching sessions with 35% hydrogen peroxide in 2 applications of 20 minutes each. In both sessions, the medication was given to the volunteers 1 hour before the bleaching procedure. The sensitivity values were obtained with the analogic visual pain scale. Tooth shade was assessed before and after bleaching. Statistical analysis was done through the one-way ANOVA and Tukey post-hoc tests. RESULTS: For bleaching sensitivity, there were statistically significant differences among the medications (P< 0.01). The lowest sensitivity means were found in the CP group (PL:4.7 = IB:4.8 > CP:1.0). In regards to tooth shade, participant's teeth were statistically significantly lighter after bleaching than before bleaching (P< 0.01), with no statistically significant difference between the medications (P< 0.05). CLINICAL SIGNIFICANCE: The use of codeine + paracetamol 1 hour before in-office tooth bleaching can drastically reduce immediate sensitivity.

Detection of Hydrocodone and Morphine as Metabolites in Oral Fluid by LC-MS/MS in Patients Prescribed Codeine.

A retrospective analysis of oral fluid drug testing results using LC-MS/MS was performed to determine the prevalence rates in oral fluid for codeine (COD) and 3 COD metabolites-morphine (MOR), norhydrocodone (NHC), and hydrocodone (HCOD). Oral fluid samples were collected using Quantisal oral fluid collection device (Immunalysis Inc.) and submitted to Millennium Health, LLC for the routine drug analysis by LC-MS/MS. Consistent with previously published literature, COD was the primary analyte detected in oral fluid after the use of COD. In COD-positive samples, HCOD, MOR, and NHC were detected at rates of 68.4%, 18.4%, and 6.3%, respectively. Concentration ranges of these analytes were 1.0 to >2000 ng/mL for COD, 1.0-20.2 ng/mL for MOR, 1.0-740.0 ng/mL for HCOD, and 2.1-47.5 ng/mL for NHC. In contrast to urine, where HCOD is typically detected as a minor metabolite of COD, HCOD was the most commonly detected metabolite in oral fluid in samples testing positive for COD with reported prescriptions for COD. This observation suggests that care should be taken when interpreting HCOD positives in oral fluid results, and that the use of COD should be considered as one possible explanation for HCOD positives.