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A crossover design lets participants experience both treatment conditions, but the order of those conditions can still matter. When a finding depends on sequence, the explanation requires more than calling the second condition effective.

What did participants receive?

Johnson and colleagues’ 2005 laboratory study enrolled 18 adults with methamphetamine dependence who were not seeking treatment. Two eight-day inpatient periods, separated by at least a week, compared oral isradipine with placebo. Isradipine included 30 mg sustained release nightly and 15 mg immediate release two hours before challenge sessions. Intravenous methamphetamine challenges were 0, 15 and 30 mg.

Selected liking and stimulation-related effects were reduced principally when placebo came first and isradipine second. The reverse sequence did not show the same pattern. The investigators proposed conditioning among several explanations, also identifying possible unblinding from adverse effects. Headaches occurred in 15/18 participants during isradipine versus 6/18 during placebo.

What sequence dependence can and cannot establish

The pattern shows that the treatment comparison was not independent of experimental history. It does not identify which aspect of that history produced the difference.

Conditioning is one candidate explanation: an earlier drug experience might change how a later experience is perceived. Expectation, recognition of side effects, period effects or other unmeasured influences could also contribute. Distinguishing these possibilities requires evidence designed to separate them.

It would therefore be too strong to describe this experiment as proving that isradipine works through conditioning. The proposed mechanism is an interpretation of the pattern, not a separately isolated intervention demonstrating that conditioning was necessary or sufficient.

Why the blinding question is substantive

A nominally blinded comparison can still be affected if participants infer their treatment from recognizable effects. A difference in headache experience does not prove that blinding failed, but it supplies a concrete reason to examine that possibility when outcomes depend on subjective judgments.

The correct account preserves the observation and the uncertainty together. Dismissing every rating because unblinding was possible would go beyond the evidence. Ignoring the possibility while claiming an established central mechanism would also go beyond it.

This was a small controlled exposure experiment, not an outpatient trial of sustained methamphetamine abstinence. Its value is in defining a conditional laboratory result and the next questions needed to explain it. It does not establish a generally effective treatment regimen or justify using isradipine to counteract methamphetamine.

Source

Johnson BA, et al. Effects of isradipine, a dihydropyridine-class calcium-channel antagonist, on d-methamphetamine’s subjective and reinforcing effects. Int J Neuropsychopharmacol. 2005;8:203–213. doi:10.1017/S1461145704005036. Publisher full-text PDF.

Similar symptom scores among observed patients do not establish that two treatment regimens are equally acceptable. Adverse effects and discontinuation are outcomes in their own right, and they affect which patients remain available for later assessments.

The inpatient comparison

Wang and colleagues’ 2016 report randomized 42 patients with methamphetamine-associated psychosis, 21 per arm, to aripiprazole or risperidone during a 25-day inpatient study. The planned oral protocols allowed aripiprazole 5–15 mg/day and risperidone up to 6 mg/day. The archived manuscript also contains a discordant 9-mg risperidone statement; the protocol range should not be treated as verified individual dosing.

Psychosis scores improved in both groups without significant between-group differences. Retention was lower with aripiprazole (p=0.007). Reported akathisia occurred in 13/21 versus 6/21 patients (p=0.03), and agitation in 11/21 versus 4/21 (p=0.02). Enrollment stopped at 42 rather than the planned 120 because of adverse effects and dropout.

Two distinct questions about treatment performance

The study lacked placebo, was not fully blinded and allowed ancillary medication. The authors acknowledged that symptom improvement could not be separated reliably from self-abatement during abstinence.

The symptom question asks how measured illness severity changed. The retention question asks whether patients continued the assigned regimen. A treatment description should report both. Omitting discontinuation can make the experience of those who tolerated treatment appear to represent everyone initially assigned.

A nonsignificant difference in symptom scores is also not a formal demonstration of equivalence. Establishing equivalence requires an appropriate margin and sufficiently precise evidence. A small comparison terminated early cannot acquire that conclusion simply because its symptom p value exceeded a conventional threshold.

Why the dosing discrepancy matters

The inconsistent passage is a reason to limit dose-specific inference, rather than silently choose whichever number fits a preferred interpretation. Without clarifying information, the article cannot supply a reliable individual dose–response analysis from that text.

The same discipline applies to the adverse-event findings. The counts describe this selected inpatient sample and its accompanying treatment practices. They should not be transformed into universal event probabilities for all people receiving either medicine.

This historical study identifies a meaningful tolerability and retention difference while leaving important efficacy questions unresolved. It does not establish the cause of psychosis in an individual, demonstrate that every symptom resulted from methamphetamine, or provide a current treatment-selection rule.

Source

Wang G, et al. Aripiprazole and risperidone for treatment of methamphetamine-associated psychosis in Chinese patients. J Subst Abuse Treat. 2016;62:84–88. doi:10.1016/j.jsat.2015.11.009. Full-text author manuscript.

An improvement during treatment is not automatically an effect of the assigned medication. A placebo-controlled comparison helps distinguish a shared study-course change from the added effect of the drug.

The between-group result

Coffin and colleagues’ 2013 double-blind trial randomized 90 actively using adults with methamphetamine dependence, 45 per arm, to oral aripiprazole or placebo for 12 weeks with weekly counseling. The registered schedule increased from 5 mg/day in week one to 10 mg in week two and 20 mg thereafter.

The primary urine-positivity comparison was nonsignificant: RR 0.88, 95% CI 0.66–1.19, p=0.41. In the placebo arm, positive specimens declined from 33/45 at baseline to 18/40 at the final visit; corresponding aripiprazole figures were 34/44 and 20/35. Electronic-container and self-reported adherence estimates were 42% and 74% overall. Akathisia, fatigue and drowsiness were reported more frequently with aripiprazole.

Why the denominators should accompany the percentages

The final percentages concern available observations from fewer participants. A percentage alone can conceal that change. Preserving the counts prevents an apparent trend from being mistaken for a complete series of measurements on everyone originally assigned.

The randomized model, rather than a visual comparison of two before-and-after percentages, addresses the primary treatment question. A decline in each arm can reflect features common to both arms. It cannot, by itself, establish which component of the study produced the improvement.

Did low adherence make the trial positive in principle?

Limited adherence constrains an exposure-based interpretation. It does not establish that the medicine would have worked if every dose had been taken. That is a further causal claim requiring supporting evidence.

Electronic-container openings and self-report also measure different things. An opening is not direct observation of swallowing; a report is not a continuous biological record. Disagreement between them should prompt attention to the measurement process, without automatically assigning one estimate the status of exact ingestion.

The confidence interval preserves another boundary: the null comparison is not proof of precisely zero effect. It also does not establish the favorable effect suggested by the point estimate alone. The uncertainty and the prespecified comparison belong together.

This historical trial did not demonstrate a methamphetamine-use benefit under its tested conditions. It does not decide whether aripiprazole is appropriate for a separate psychiatric indication, which would require evidence about that condition and the individual clinical context.

Sources

Coffin PO, et al. Aripiprazole for the treatment of methamphetamine dependence: a randomized, double-blind, placebo-controlled trial. Addiction. 2013;108:751–761. doi:10.1111/add.12073. Full text. The dosing schedule is also documented in the trial registration, NCT00497055.

A trial’s randomized denominator and its analyzed denominator are not always the same. Reading the participant flow can change the interpretation of an apparently complete follow-up result.

The numbers behind the abstract

Ahmadi and colleagues’ 2019 report compared methamphetamine-withdrawal craving during 14 inpatient days. The full results describe 69 randomized men: 35 assigned buprenorphine and 34 bupropion. Four bupropion-assigned patients refused medication initially, leaving 35 and 30 treated participants; all 65 completed follow-up.

Day-one doses were sublingual buprenorphine 4 mg or oral bupropion 150 mg. Days 2–14 used 8 mg/day or 300 mg/day, respectively, divided twice daily. Daily craving ratings used a 0–10 scale. The reported group effect favored buprenorphine (p=0.011), while the group-by-day interaction was nonsignificant. No placebo or untreated group was included.

Completion among starters is not completion among everyone randomized

Describing the study simply as 65 randomized participants with 100% completion would omit the four post-assignment refusals. Completion of follow-up among those who began treatment answers a different question from retention of every randomized participant.

This matters because removing people after assignment can compromise the original group comparison. The direction and size of any resulting bias cannot be established merely from the fact that no further participants dropped out. A transparent explanation preserves both the randomized and treated counts.

What does a comparison without placebo establish?

The two active regimens can be compared within the study’s design and analytical limitations. Declining craving in both groups, however, cannot establish that both medicines caused the decline. Time, inpatient abstinence and other features of the setting provide alternative explanations that the shared before-and-after pattern cannot separate.

The nonsignificant group-by-day interaction also should remain visible. A group-level difference and a demonstrated difference in the trajectory over time are different statistical statements. Calling one a progressively increasing treatment advantage would require evidence directed at that trajectory.

Why this was not a relapse-prevention trial

The observation period concerned withdrawal craving in a controlled inpatient environment. It did not establish what happened after discharge or whether either regimen prevented return to use in the community. A recommendation about long-term relapse prevention would require that outcome to be followed and compared.

The paper is therefore useful historical evidence about a short, selected active-treatment comparison. Its dosing description records what was studied; it is not an instruction to start either medication for methamphetamine craving.

Source

Ahmadi J, Sahraian A, Biuseh M. A randomized clinical trial on the effects of bupropion and buprenorphine on the reduction of methamphetamine craving. Trials. 2019;20:468. doi:10.1186/s13063-019-3554-6. Publisher full text.

Two analyses can use the same participants and still estimate different quantities. A comparison of final-month drug-use days and a comparison of improvement from baseline should not be collapsed into a single verdict about treatment effectiveness.

The trial and its two comparisons

Ling and colleagues’ 2014 double-blind trial randomized 110 adults with methamphetamine dependence, 55 per arm. Oral sustained-release methylphenidate increased from 18 mg/day in week one to 36 mg in week two and 54 mg during weeks 3–10. Both arms received counseling and incentives; four subsequent weeks used single-blind placebo.

The primary comparison of reported methamphetamine-use days in the final 30 days of active treatment was nonsignificant (p=0.22). A planned secondary change-from-baseline analysis favored methylphenidate: reductions of 6.56 versus 3.82 days (p=0.05). Urine outcomes at week ten did not distinguish groups. The authors identified dropout, small sample size and adherence measurement as limitations.

Why the baseline question matters

A final-period value describes the outcome at the chosen endpoint. A change score includes both the starting value and the endpoint. Those questions can yield different results without either calculation necessarily being erroneous.

The appropriate summary identifies which analysis was primary and which was secondary, then describes the evidence for each. A favorable secondary comparison can support further investigation. It cannot silently replace the prespecified primary comparison after the results are known.

Baseline severity also matters when comparing studies or discussing subgroups. A participant’s opportunity to reduce reported use depends partly on their starting frequency. The relevant analysis must distinguish that structure from a claim that a particular severity category has a proven biological response to medication.

Reported days, urine results and treatment phase

Self-report and urine testing supply related but different observations. A day-count endpoint should remain a day-count endpoint, and the urine comparison should be reported on its own terms. Agreement should be demonstrated rather than assumed.

The switch to placebo after active treatment is another important boundary. An observation in that later phase should not be described as a result during ongoing active medication. A case review or trial comparison should preserve when each outcome was collected relative to the regimen.

This historical study provides a useful example of how outcome selection affects interpretation. Its mixed pattern supports a precise account of the tested regimen and analytical hierarchy, without establishing a universal methylphenidate treatment effect, an individualized prognosis or a current dosing recommendation for methamphetamine use disorder.

Source

Ling W, et al. Sustained-release methylphenidate in a randomized trial of treatment of methamphetamine use disorder. Addiction. 2014;109:1489–1500. doi:10.1111/add.12608. Full text.

A false-positive statistic changes meaning when its denominator changes. In a frequently cited bupropion study, 41% described medication histories among unconfirmed positive screens. It was not the incidence of false positives among everyone taking the medicine.

Reconstructing the tested population

Casey and colleagues’ 2011 retrospective hospital study examined 10,011 urine drug screens. Syva EMIT II Plus amphetamine screening was positive in 362; GC–MS confirmed 234, while 128 failed to confirm. The study counted dextroamphetamine, methamphetamine or MDMA detection as confirmation. Recorded bupropion use occurred in 53 of those 128 unconfirmed results (41%), and in three confirmed results.

The investigators reviewed records after a positive amphetamine screen. They did not establish the total number of bupropion-treated patients among all screen-negative patients. Medication lists could be incomplete, adherence was unverified and the population came from one urban trauma-center setting. The findings were specific to the evaluated testing process.

Two different conditional probabilities

The observed proportion answers: among unconfirmed amphetamine-positive screens, how often was bupropion recorded? The patient-facing question is different: among people taking bupropion, how often will screening produce an unconfirmed positive?

Answering the second question requires the complete denominator of exposed people who underwent the relevant testing, including those with negative screens. A sample selected on a positive screening result cannot supply that missing denominator. Reversing the conditional probability would turn the study into an incidence estimate it did not calculate.

Does the prescription prove interference in a particular specimen?

No. A documented prescription identifies a plausible analytical question. It does not establish ingestion, the relevant drug or metabolite concentration, or the cause of an antibody response in a specific sample. The confirmatory result and the exact assay remain essential parts of the explanation.

The three confirmed results among records noting bupropion also matter. A medication history does not make a positive result automatically false. A particular person can have the medication recorded and a target compound confirmed; the two observations are not mutually exclusive.

Nor should the hospital proportion be transferred to another immunoassay platform without supporting evidence. A reported interference concerns a particular analytical process. Its relevance depends on the actual method used in the case being reviewed.

A defensible use of the paper

The study supports taking an unexpected amphetamine screen seriously as a question for confirmation and method review. It does not establish an individual’s drug source, impairment or credibility from medication history alone. Keeping the 53/128 denominator attached to the 41% figure prevents a useful historical observation from becoming a misleading personal risk estimate.

Source

Casey ER, Scott MG, Tang S, Mullins ME. Frequency of false positive amphetamine screens due to bupropion using the Syva EMIT II immunoassay. J Med Toxicol. 2011;7:105–108. doi:10.1007/s13181-010-0131-5. Full text.

An association between a urine screen and a blood-cell count can identify an interpretive possibility without identifying the cause of an individual’s abnormal result. The distinction matters when a positive screen is used to stop investigating other explanations.

What did the historical comparison show?

Richards and colleagues’ 2014 retrospective study analyzed 1,206 emergency-department visits for psychiatric medical clearance. There were 877 visits with urine screens negative for both amphetamines and cocaine, 240 amphetamine-positive/cocaine-negative, 72 cocaine-positive/amphetamine-negative and 17 positive for both.

Mean white-cell counts were 8.4 ± 2.6, 9.4 ± 3.3, 7.1 ± 1.8 and 10.0 ± 4.2 × 10³/µL, respectively; spreads are standard deviations. Counts above the laboratory’s 11.0 × 10³/µL upper boundary occurred in 57/240 amphetamine-only visits (23.8%) versus 130/877 controls (14.8%, p=0.001).

The study used qualitative amphetamine-class screening, excluded selected medical presentations including elevated temperature, and lacked medication reconciliation, exposure timing and white-cell differential counts.

The screening class was not a methamphetamine-specific dose

The exposure category included amphetamine derivatives rather than a measured methamphetamine concentration. A class-positive group therefore should not be relabeled as people with a known methamphetamine dose, route or time of use.

Likewise, the outcome was a circulating cell count. It did not directly measure a particular brain inflammatory process, establish infection status in every future patient or identify which cell population accounted for the increase. Those questions require their own observations.

Why the cocaine comparison does not prove a protective effect

The lower mean count in the cocaine-only group is also an association in selected visits. It does not establish that cocaine prevents leukocytosis. Differences in the people, their presentation, timing or other exposures can affect a comparison even when its p value is small.

For the same reason, the higher count in the amphetamine-positive group does not isolate a pharmacological cause. A retrospective comparison without complete information on relevant alternative explanations cannot assign the entire difference to the drug category.

The useful case-review approach is to preserve the original units and category definitions, then examine what was actually documented in the person’s record. A positive urine screen is one observation to interpret alongside the examination and other findings. It cannot establish that an elevated white-cell count is harmless or permit an individual causal diagnosis from the group average.

Source

Richards JR, Farias VF, Clingan CS. Association of leukocytosis with amphetamine and cocaine use. ScientificWorldJournal. 2014;2014:207651. doi:10.1155/2014/207651. Full text. Historical observational evidence.

A prospectively measured genotype does not automatically become a clinically useful treatment-selection test. The design must distinguish a general prognostic difference from a difference in the effect of the treatment itself.

What comparison did the pilot actually make?

Pal and colleagues’ 2015 open-label pilot enrolled 11 methamphetamine-dependent participants with the OPRM1 A118G variant and 11 with A118A. All received one 380-mg intramuscular sustained-release naltrexone injection and weekly psychotherapy during a four-week treatment phase. Staff with participant contact and participants were blinded to genotype.

Mean methamphetamine-negative urine counts were 1.7 versus 1.8, respectively (p=0.97); reported abstinent days were 11.5 versus 14.8 (p=0.51). The urine screen cutoff was 1,000 ng/mL. Other abstinence comparisons also were nonsignificant. The authors emphasized the small sample and absence of placebo groups.

Selection was not random assignment to genotype or drug

The investigators prospectively screened genotypes and selected a comparison group balanced on sex and recent-use frequency. That procedure helped form comparable groups on selected characteristics. It did not randomly assign the genetic variant, and everyone received the same active medication.

To establish that a variant selects treatment benefit, the important question is whether the treatment-versus-comparator effect differs by genotype. Comparing two genotype groups after both receive treatment does not supply that interaction. Even a positive difference could reflect prognosis, other group characteristics or the treatment response; the design would need to distinguish those explanations.

The null result does not validate interchangeability either. With 11 participants per group, a failure to find a difference is not the same as demonstrating sufficiently similar effects within a prespecified margin.

Why another substance’s result cannot fill the gap

A pharmacogenetic finding from treatment of alcohol problems would motivate a methamphetamine study, rather than establish its answer. The relevant outcome, population and treatment context must be tested. A shared medication name does not make two disorders the same experimental setting.

For a client assessing a proposed genetic opinion, the practical question is whether the claimed prediction has been validated for the intended decision. That includes the alternative treatment, the target population and the outcome being predicted. A small exploratory group comparison cannot supply all three by implication.

This historical pilot therefore leaves genotype-guided naltrexone treatment for methamphetamine dependence unresolved. It supports neither a validated individual forecast nor a conclusion about medication efficacy relative to placebo, which was not part of the experiment.

Source

Pal R, et al. Impact of prospectively determined A118G polymorphism on treatment response to injectable naltrexone among methamphetamine-dependent patients: an open-label, pilot study. J Addict Med. 2015;9:130–135. doi:10.1097/ADM.0000000000000107. Full text.

A drug can reach serum without establishing that its proposed brain mechanism occurred. That distinction helps interpret a negative medication trial without declaring either the entire mechanism disproved or the treatment effective despite the result.

The clinical outcome remained negative

Heinzerling and colleagues’ 2020 report randomized 125 adults with methamphetamine use disorder to oral ibudilast 50 mg twice daily (64 participants) or placebo (61) for 12 weeks, with medication-management counseling.

End-of-treatment abstinence was 14% with ibudilast and 16% with placebo, without a significant difference. Classification required an available specimen in each of weeks 11 and 12 and no positive specimen in either week; missing both specimens in either week meant failure. Serum ibudilast at week three was available for 59 treated participants. Levels did not significantly correlate with the treatment-effectiveness score (r=0.008, p=1.00).

Exposure, adherence and target engagement

The authors identified limited adherence, a population with frequent baseline use and power to detect a moderate rather than every smaller effect as limitations. The trial did not establish that ibudilast improved abstinence.

A serum measurement is an observation of exposure in that specimen at that time. It cannot independently document every dose over the preceding or following weeks. Calling the level proof of continuous adherence would change the time interval covered by the evidence.

Target engagement is a further question: did the relevant biological target respond in the intended tissue? Measuring serum drug does not itself measure a change in brain inflammatory activity. A credible mechanism claim needs evidence directed at that target, alongside an appropriate account of where and when it was measured.

What does the null trial say about neuroinflammation?

The randomized clinical comparison addresses the tested treatment regimen and outcome. It does not isolate every action of a compound or establish that one proposed mechanism caused the null result. Conversely, a plausible mechanism cannot substitute for a favorable clinical comparison.

The abstinence definition also deserves to remain intact. It was a rule about available urine observations in two final weeks. It should not become a claim of uninterrupted biologically observed abstinence throughout the entire treatment period.

For an expert opinion, three questions should therefore be stated separately: whether the medicine was detected, whether its intended target was affected, and whether the clinical outcome improved. Evidence for one question should not be borrowed to answer the others. This historical outpatient trial supplies a clear negative abstinence comparison while leaving mechanistic questions for appropriately designed research.

Source

Heinzerling KG, et al. Randomized, placebo-controlled trial of targeting neuroinflammation with ibudilast to treat methamphetamine use disorder. J Neuroimmune Pharmacol. 2020;15:238–248. doi:10.1007/s11481-019-09883-w. Full text.

Treatment engagement can improve without a demonstrated reduction in drug use during the same study. A trial should be credited for the outcome it measured successfully, while keeping the separate drug-use result visible.

What was randomized and analyzed?

Stauffer and colleagues’ 2020 double-blind trial evaluated intranasal oxytocin 40 IU or placebo before six weekly motivational interviewing group sessions for men who have sex with men and severe methamphetamine use disorder. Forty-eight participants attended the first session and entered the primary analysis: 24 per arm, across five therapy cohorts per arm.

The attendance model excluded session one, which everyone in that analysis attended. Oxytocin increased subsequent attendance odds: OR 3.26, 95% CI 1.27–8.41, p=0.014. The investigators did not find a methamphetamine-use benefit or a craving difference. They accounted for repeated observations within participants but not dependence within therapy cohorts. People who never attended session one were excluded.

What does an attendance odds ratio mean?

The ratio concerns the odds of attendance in the fitted session model. It is not a statement that 3.26 times as many people completed treatment, nor that methamphetamine consumption fell by that factor. Both the outcome and its statistical scale should accompany the number.

The confidence interval also belongs with the estimate. Reporting only the point estimate would hide the range of effect sizes compatible with the model and data. A small study’s apparently large estimate should not be presented as a precisely established constant for other programs.

Participants and therapy cohorts are different units

Group treatment creates potential shared influences: the therapist, session atmosphere and interactions between members. Repeated measurements from one person and shared experiences within a cohort represent different sources of dependence. Adjusting for one does not automatically account for the other.

The first-session requirement adds another boundary. The result concerns participants who reached that starting point. It cannot establish that oxytocin brings people into their first visit, because those who never attended did not receive the intervention and were outside the analysis.

What would establish a broader treatment benefit?

A larger trial could test whether an engagement benefit persists and translates into the desired clinical outcome. That translation should be measured directly. Improved attendance is a potential step in a treatment pathway, not proof that every later step occurred.

This historical human trial therefore adds a different kind of evidence from animal oxytocin experiments: a specific attendance result in a defined therapy setting, accompanied by null drug-use findings. It does not establish general effectiveness for methamphetamine abstinence or supply a current instruction to use an intranasal medicine.

Source

Stauffer CS, et al. Oxytocin-enhanced group therapy for methamphetamine use disorder: Randomized controlled trial. J Subst Abuse Treat. 2020;108059. doi:10.1016/j.jsat.2020.108059. Full text.