Revamping the ever-changing landscape of drug development processes in the midst of COVID-19 pandemic

Oncology is the frontline of drug development. The current pharmaceutical pipeline is disproportional focused on oncology, where about 1/3 of all phases of development is in this therapeutic area. The emphasis brings about substantial breakthroughs and has made positive impact on the quality of life. However, oncology remains a threat to human existence. To facilitate this process, a comprehensive list of novel/first molecularly targeted oncology drug approvals by the FDA from 2017 to 2020 is assessed. Here, we focus on molecularly targeted oncology drugs and not cytotoxic ones, although the latter remain important. To achieve this purpose, besides their sponsors, years of approval, drug classes, and cancer indications, clinical significance is included. The results show that approved molecularly targeted drugs span across diverse classes, including small molecule receptor inhibitors, and biologics such as monoclonal antibodies, antibody-drug conjugates, check-point inhibitors (i.e., PD1, PDL1, CTLA4) and CAR-T cell therapies. Although complete cure of cancer remains limited, we have made substantial inroads and more is yet to come. Moreover, many of these new knowledge can be extrapolated to other therapeutic areas, especially to those of currently unmet medical needs such as in neurology and other chronic diseases.

Graves Disease Following the SARS-CoV-2 Vaccine: Case Series

Widespread vaccination is a principal strategy to mitigate the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and lessen the global burden of coronavirus disease 2019 (COVID-19). Information is rapidly evolving about the impact of SARS-CoV-2 vaccines on the immune and endocrine systems. This case series heightens clinical awareness of possible thyroid effects and conveys knowledge of what to monitor, which are fundamental components of public health and pharmacovigilance. We present a case series of Graves disease following mRNA SARS-CoV-2 vaccination, with symptoms and altered thyroid function tests developing within 7 days of the first dose in 2 women aged 38 and 63 years, and 28 days after the second dose in a 30-year-old man. New-onset Graves disease occurred following administration of mRNA vaccines against SARS-CoV-2. Based on the timing of signs and symptoms relative to administration of the vaccine and the absence of other probable causes, we consider the vaccine as a potential contributor to the diagnosis. The viral spike protein, delivered indirectly through an encoded mRNA vaccine, may be capable of triggering an inflammatory cascade and immune response triggering thyroid dysfunction.

Dosing Common Medications in Hospitalized Pediatric Patients with Obesity: A Review

Medication management in children and adolescents with obesity is challenging because both developmental and pathophysiological changes may impact drug disposition and response. Evidence to date indicates an effect of obesity on drug disposition for certain drugs used in this population. This work identified published studies evaluating drug dosing, pharmacokinetics (PK), and effect in pediatric patients with obesity, focusing on 70 common medications used in a pediatric network of 42 US medical centers. A PubMed search revealed 33 studies providing PK and/or effectiveness data for 23% (16 of 70) of medications, 44% of which have just one study and can be considered exploratory. This work appraising 4 decades of literature shows several promising approaches: greater use of PK models applied to prospective clinical studies, dosing recommendations derived from both PK and safety, and multiyear effectiveness data on drugs for chronic conditions (e.g., asthma). Most studies make dose recommendations but are weakened by retrospective study design, small study populations, and no controls or historic controls. Dosing decisions continue to rely on extrapolating knowledge, including targeting systemic drug exposure typically achieved in adults. Optimal weight-based dosing strategies vary by drug and warrant prospective, controlled studies incorporating PK and modeling and simulation to complement clinical assessment.

Improved treatment satisfaction in patients with type 1 diabetes treated with insulin glargine 100U/mL versus neutral protamine Hagedorn insulin: An exploration of key predictors from two randomized controlled trials

AIM

Investigate contributors to treatment satisfaction in type 1 diabetes (T1D).

METHODS

Post-hoc analysis using the Diabetes Treatment Satisfaction Questionnaire status version (DTSQs) in 771 T1D patients from two 28-week trials comparing once-daily insulin glargine 100U/mL (Gla-100) with once- or twice-daily NPH neutral protamine Hagedorn (NPH) insulin.

RESULTS

Gla-100 was associated with a significant improvement in treatment satisfaction versus NPH (overall population adjusted mean [standard error] DTSQs change from baseline: +1.13 [0.30] versus -0.04 [0.31]; p=0.006). In the overall population, treatment satisfaction improvement with all insulin regimens was related to less frequent severe hypoglycemia (coefficient-0.077; p=0.040) and HbA1c reduction (-0.066; p=0.082). By treatment regimen, relationships between treatment satisfaction and these outcomes approached or attained statistical significance for NPH insulin, but not Gla-100. In the overall population, predictors of treatment satisfaction improvement included: Gla-100 treatment (estimate 1.17, p=0.006), lower baseline DTSQs (-0.57, p<0.001), study (-1.01, p=0.019), lower severe hypoglycemia rate (0.17, p=0.012), and higher baseline HbA1c (0.44, p=0.014). By treatment regimen, these predictors remained significant for NPH insulin.

CONCLUSIONS

Gla-100 resulted in a significant improvement in treatment satisfaction versus NPH insulin, independent of baseline disease characteristics and clinical outcomes.

Oral noribogaine shows high brain uptake and anti-withdrawal effects not associated with place preference in rodents

This study investigated the effects of noribogaine, the principal metabolite of the drug ibogaine, on substance-related disorders. In the first experiment, mice chronically treated with morphine were subjected to naloxone-precipitated withdrawal two hours after oral administration of noribogaine. Oral noribogaine dose dependently decreased the global opiate withdrawal score by up to 88% of vehicle control with an ED50 of 13 mg/kg. In the second experiment, blood and brain levels of noribogaine showed a high brain penetration and a brain/blood ratio of 7±1 across all doses tested. In a third experiment, rats given oral noribogaine up to 100 mg/kg were tested for abuse liability using a standard biased conditioned place paradigm. Noribogaine-treated rats did not display place preference, suggesting that noribogaine is not perceived as a hedonic stimulus in rodents. Retrospective review of published studies assessing the efficacy of ibogaine on morphine withdrawal shows that the most likely cause of the discrepancies in the literature is the different routes of administration and time of testing following ibogaine administration. These results suggest that the metabolite noribogaine rather than the parent compound mediates the effects of ibogaine on blocking naloxone-precipitated withdrawal. Noribogaine may hold promise as a non-addicting alternative to standard opiate replacement therapies to transition patients to opiate abstinence.

Patterns of postprandial hyperglycemia after basal insulin therapy: individual and regional differences

BACKGROUND

Treatment of postprandial hyperglycemia could be needed when basal insulin added to oral therapy does not maintain glycated haemoglobin (HbA1C ) targets in type 2 diabetes mellitus. Knowing individual and regional patterns of postprandial hyperglycemia in this setting might improve therapeutic decisions.

METHODS

Patient-level self-monitored blood glucose data were pooled from six studies of insulin glargine for patients with HbA1C  ≥ 7.0% after 24 weeks. Percentages of participants with highest daily postprandial blood glucose and greatest postprandial increments after each of the three daily meals were calculated and compared between four geographical regions; USA, Canada, Germany, and other European countries.

RESULTS

For 494 participants (mean age 60.1 years, diabetes duration 9.6 years, and BMI 29.8 kg/m(2) ), mean endpoint HbA1C was 7.8%. On insulin glargine treatment, highest postprandial blood glucose most often occurred post-dinner (44% of participants) and greatest postprandial increments post-breakfast (46% of participants) in all regions. Participants with greatest postprandial increments post-breakfast were older and experienced less HbA1C improvement with insulin glargine than those with greatest postprandial increments after other meals. Post-breakfast and post-dinner postprandial blood glucose was higher in the USA and Canada versus Germany, and in the USA versus Other European countries (all p < 0.05). Postprandial increments after dinner were greater in the USA versus all other regions.

CONCLUSIONS

Generally, highest postprandial blood glucose follows dinner and greatest postprandial increments follow breakfast. Variations in patient characteristics and eating patterns might underlie differences both within and between regions. Awareness of regional differences and evaluation of an individual's typical eating pattern might facilitate appropriate prandial therapy.

More satisfied, but why? A pooled patient-level analysis of treatment satisfaction following the initiation of insulin glargine vs. comparators in insulin-naïve patients with type 2 diabetes mellitus

AIM

To assess patient-reported outcomes associated with initiating insulin glargine among insulin-naïve patients with type 2 diabetes mellitus (T2DM).

METHODS

This was a pooled analysis of patient-level data from Phase 3, randomized controlled trials evaluating once-daily insulin glargine vs. comparator treatment for ≥24 weeks in previously insulin-naïve adult patients with T2DM and poor glycaemic control. Eligible studies utilized strict, predefined insulin titration algorithms with weekly dose-adjustment to achieve fasting plasma glucose (FPG) levels of ≤5.6 mmol/l. Treatment satisfaction was measured using the Diabetes Treatment Satisfaction Questionnaire (DTSQ) change (c) and status (s) versions.

RESULTS

A total of 1577 patients from four studies were included; 830 patients treated with insulin glargine and 747 with comparators. At week 24, DTSQc scores improved in both groups with a significantly higher increase in treatment satisfaction for insulin glargine vs. comparators (13.5 vs. 12.1; p < 0.0001). Multivariate regression analysis revealed that significant predictors of DTSQc improvement at week 24 were insulin glargine treatment (p < 0.0001), higher baseline DTSQs (p < 0.0001), and lower baseline body weight (p = 0.0103). Greater improvement in DTSQc at week 24 was significantly associated with decrease from baseline in glycosylated haemoglobin (p < 0.001) and FPG (p = 0.0001); a numerically more positive change in weight from baseline approached significance (p = 0.07).

CONCLUSION

Initiation of insulin glargine in insulin-naïve patients with T2DM is associated with greater improvements in treatment satisfaction than alternative interventions, with perceived improvements in glycaemic control and baseline weight likely to be important factors.

Comparison of three algorithms for initiation and titration of insulin glargine in insulin-naive patients with type 2 diabetes mellitus

BACKGROUND

Several titration algorithms can be used to adjust insulin dose and attain blood glucose targets. We compared clinical outcomes using three initiation and titration algorithms for insulin glargine in insulin-naive patients with type 2 diabetes mellitus (T2DM); focusing on those receiving both metformin and sulfonylurea (SU) at baseline.

METHODS

This was a pooled analysis of patient-level data from prospective, randomized, controlled 24-week trials. Patients received algorithm 1 (1 IU increase once daily, if fasting plasma glucose [FPG] > target), algorithm 2 (2 IU increase every 3 days, if FPG > target), or algorithm 3 (treat-to-target, generally 2-8 IU increase weekly based on 2-day mean FPG levels). Glycemic control, insulin dose, and hypoglycemic events were compared between algorithms.

RESULTS

Overall, 1380 patients were included. In patients receiving metformin and SU at baseline, there were no significant differences in glycemic control between algorithms. Weight-adjusted dose was higher for algorithm 2 vs algorithms 1 and 3 (P = 0.0037 and P < 0.0001, respectively), though results were not significantly different when adjusted for reductions in HbA1c (0.36 IU/kg, 0.43 IU/kg, and 0.31 IU/kg for algorithms 1, 2, and 3, respectively). Yearly hypoglycemic event rates (confirmed blood glucose <56 mg/dL) were higher for algorithm 3 than algorithms 1 (P = 0.0003) and 2 (P < 0.0001).

CONCLUSIONS

Three algorithms for initiation and titration of insulin glargine in patients with T2DM resulted in similar levels of glycemic control, with lower rates of hypoglycemia for patients treated using simpler algorithms 1 and 2.

Extending Worldwide Clinical Pharmacology Education Through a Pricing Approach

Financial instruments, such as professional membership fees, are part of the science and technology policy toolkit for creating an environment conducive to developing an international health knowledge network. To minimize a hurdle to global knowledge exchange in clinical pharmacology, the American College of Clinical Pharmacology reevaluated fees for its international members. Secondary market research was conducted on salary data available from US-based multinational firms. Salary comparisons for the same position based in the United States and in a developing economy were used to generate an index ratio. Applying this ratio, a tiered-membership fee structure was constructed for the approximately 120 countries where gross national income meets the World Bank classification of "developing economy." The index ratio serves as a paradigm for structuring fees across a variety of programs. With the implementation of an adjusted dues structure, information and networks of colleagues are now more accessible to clinical pharmacologists in developing economies.

Novel trial design: a report from the 19th frontiers symposium of ACCP

Novel approaches to drug development along with incentives to reward risk undertaken during early drug development have been proposed to improve the medical product development process. The American College of Clinical Pharmacology held its 19th Frontiers Symposium in mid-2007 to provide a forum to share new knowledge about disease progression models and adaptive and other novel trial designs. These topics reflect the changing paradigm of drug development and regulatory innovation as outlined in the Food and Drug Administration's Critical Path Initiative. This meeting report summarizes some of the presentations and panel discussions among academic, industrial, and regulatory participants regarding clinical trial design, including adaptive Bayesian approaches.

Drug interactions with grapefruit juice

Some drugs demonstrate a significantly greater (up to 3-fold) mean oral bioavailability on coadministration with grapefruit juice. With some calcium antagonists, the benzodiazepines midazolam and triazolam and the antihistamine terfenadine, changes in bioavailability are accompanied by altered drug action. Study design factors possibly contribute to the magnitude of changes in drug bioavailability; they include the source of the citrus, its intake schedule, drug formulations and individual metabolising capacity. The components of citrus juice that are responsible for clinical drug interactions have yet to be fully determined. Based on the flavonoid naringin's unique distribution in the plant kingdom, abundance in grapefruit and ability to inhibit metabolic enzymes, naringin is likely to be one of the grapefruit components influencing drug metabolism. Other components present in citrus fruit, such as furanocoumarins, may be more potent inhibitors than flavonoids and are under investigation. Conclusions drawn from clinical drug interaction studies should be considered specific to the citrus fruit products evaluated because of the variation in their natural product content. The predominant mechanism for enhanced bioavailability is presumably the inhibition of oxidative drug metabolism in the small intestine. The consistent findings across studies of diverse cytochrome P450 (CYP) 3A substrates support the mechanistic hypothesis that 1 or more grapefruit juice components inhibit CYP3A enzymes in the gastrointestinal tract. The evaluation of the need to avoid the concomitant intake of grapefruit products with drugs is best done on an individual drug basis rather than collectively by drug class. Based on the narrow therapeutic range of cyclosporin and research experience in organ transplant recipients, its interaction with grapefruit juice is likely to be clinically significant.

Flavanone absorption after naringin, hesperidin, and citrus administration

Disposition of citrus flavonoids was evaluated after single oral doses of pure compounds (500 mg naringin and 500 mg hesperidin) and after multiple doses of combined grapefruit juice and orange juice and of once-daily grapefruit. Cumulative urinary recovery indicated low bioavailability ( < 25%) of naringin and hesperidin. The aglycones naringenin and hesperitin were detected in urine and plasma by positive chemical ionization-collisionally activated dissociation tandem mass spectrometry (PCI-CAD MS/MS). After juice administration, PCI-CAD MS/MS detected naringenin, hesperitin, and four related flavanones, tentatively identified as monomethoxy and dimethoxy derivatives. These methoxyflavanones appear to be absorbed from juice. Absorbed citrus flavanones may undergo glucuronidation before urinary excretion.

Kinetic and inhibitor studies of acetaminophen and zidovudine glucuronidation in rat liver microsomes

The antiviral drug zidovudine (ZDV) and the analgesic and antipyretic agent acetaminophen (AP) are both biotransformed in the liver of humans to ether glucuronides. A previous clinical trial of ZDV suggested the potential for a clinically significant interaction between AP and ZDV, probably based upon competing hepatic metabolism. To study the mechanism of this potential competition between AP and ZDV as substrates for uridine diphosphoglucuronyltransferase (UDPGT), enzyme kinetic studies were performed using rat liver microsome preparations. Cross inhibition studies demonstrated that AP glucuronidation was competitively inhibited by ZDV, while ZDV glucuronidation was slightly inhibited by AP in a noncompetitive interaction.

Rapid mucosal absorption of topical lidocaine during bronchoscopy in the presence of oral candidiasis

Local anesthetic agents are topically applied during diagnostic procedures such as bronchoscopy. These routine procedures are associated with only rare reports of drug toxicity or extensive systemic drug absorption. We report a case of rapid systemic absorption and elevated plasma lidocaine concentrations following a fiberoptic bronchoscopy procedure in a man with oral candidiasis and lung cancer.

Renal and hemodynamic responses to bumetanide in hypertension: effects of nitrendipine

The effects of a calcium antagonist on the response to a loop diuretic were tested in eight hypertensive patients while they received 120 mmol.24 hr-1 of dietary Na. Nitrendipine (N; 20 mg) or placebo (P) was administered twice daily for five days and bumetanide (B; 1 mg, i.v.) for the last three days of each period. Cardiac index (CI) was measured during tilt. B alone significantly (P less than 0.05; N = 7) reduced CI and increased total peripheral resistance; N prevented these effects of B. Neither drug altered BP consistently. Although three days of B increased plasma renin activity (PRA) during P and N, it increased plasma aldosterone (PAldo) only during P (P, 4.4 +/- 1.3 to 7.6 +/- 1.0; P less than 0.05, N, 5.7 +/- 1.3 to 6.0 +/- 1.3; pg.liter-1; NS). B increased Na excretion without changing GFR or RPF; this was followed by 18 hours of decreased renal Na excretion. These actions were unchanged by N. N did not change the cumulative excretion of B (P, 268 +/- 35 vs. N, 217 +/- 21 micrograms) or the relationship between Na excretion and the log of B excretion. However, Na excretion was increased (P less than 0.05) by 40 to 60% in the six hour period following the first two doses of N. Therefore, the cumulative Na balance was more negative during five days of N (P, -47 +/- 17 vs. N, -108 +/- 24 mmol; P less than 0.05). The effect of N and B on Na balance were independent.(ABSTRACT TRUNCATED AT 250 WORDS)

Rifampin-associated thrombocytopenia secondary to poor compliance

Rifampin can be associated with severe adverse effects such as hepatitis, acute renal failure, hemolytic anemia, and thrombocytopenia. Thrombocytopenia has traditionally been associated with intermittent therapy. This article reports the occurrence of rifampin-associated thrombocytopenia in an indigent patient after a four-month lapse in therapy for pulmonary tuberculosis. The patient's platelet count dropped rapidly to a level of 1000/mm3 after receiving a single 600 mg dose of rifampin. After returning to a normal level of greater than 100,000/mm3, the patient's platelets again dropped to 1200/mm3 with readministration of rifampin. The long-term therapy necessary to eradicate the Mycobacterium tuberculosis organism makes economic considerations important. This patient and other indigent patients who may be poor compliers because they are unable to buy the necessary medication may be at a higher risk for adverse reactions.

Systemic absorption of topical lidocaine in elderly and young adults undergoing bronchoscopy

This study compared the systemic absorption of topically administered lidocaine in elderly and young adult patients who were undergoing fiberoptic bronchoscopy. Fourteen elderly subjects aged 60-72 years (mean 67 years) and five young subjects age 31-48 years (mean 42 years) were compared with respect to dosage requirements to achieve satisfactory local anesthesia, rate and extent of lidocaine systemic absorption, plasma drug levels, elimination half-life, and drug side effects. Blood samples were drawn prior to, during, and for an average of 3 hours after the completion of bronchoscopy. Lidocaine plasma concentrations averaged in the range of 3.04-0.88 micrograms/ml from the beginning of the procedure to the end of blood sampling. Despite high cumulative amounts of 19 mg/kg (1200 mg) of lidocaine administered topically, the regimen proved relatively safe and achieved satisfactory anesthesia. In patients without known risk factors either for delayed hepatic lidocaine clearance or for enhanced mucosal absorption, the regimen is suitable for both young and old individuals.

Paracetamol absorption from a feeding jejunostomy

Disposition of paracetamol oral elixir was determined in two male patients after administration via feeding jejunostomy and compared with four male controls who received the same dose by mouth. Area under the plasma concentration-time curve, elimination half-life, and time to maximum concentration were similar in both groups after 650 mg paracetamol elixir. The absolute amounts and ratio of paracetamol glucuronide to sulphate, the major urinary metabolites after therapeutic paracetamol doses, were similar after jejunal administration as compared to oral administration. Paracetamol is absorbed and biotransformed in a similar manner after either jejunal or oral administration. Therefore, it may be administered effectively via jejunostomy tube in patients who require this route of administration.

Usefulness of oral dipyridamole suspension for stress thallium imaging without exercise in the detection of coronary artery disease

Stress thallium imaging with intravenous dipyridamole permits assessment of coronary artery disease (CAD) without the need for exercise. However, intravenous dipyridamole is available in the United States only on an experimental basis. To study the use of oral dipyridamole as a clinically available alternative to intravenous dipyridamole for this purpose, 100 patients underwent thallium imaging with oral dipyridamole. Each patient received 300 mg of pulverized tablets in a 30-ml suspension. Maximal increase in mean heart rate and decrease in mean blood pressure occurred 30 minutes after ingestion. At 45 minutes, 2 mCi of thallium was given intravenously and serial imaging was begun within 7 minutes. The serum dipyridamole level (mean +/- standard deviation) 45 minutes after 300 mg was administered orally (3.7 +/- 2.2 micrograms/ml) was similar to that 5 minutes after 0.56 mg/kg was given intravenously (4.6 +/- 1.3 micrograms/ml). Fifty-five patients had some adverse effects between 15 and 75 minutes after oral ingestion, including nausea, headache, dizziness, chest pain (25 patients) and electrocardiographic changes (14 patients). Intravenous aminophylline was used to resolve these adverse effects in 21 patients. There were no severe arrhythmias, myocardial infarctions or deaths. Of the 43 patients with angiographically documented CAD, 39 had an initial perfusion defect that redistributed on the delayed images. When the results in patients who had undergone catheterization were analyzed by individual segment, the presence of thallium redistribution was associated with normal or hypokinetic contrast left ventriculographic wall motion of that segment, whereas the presence of a persistent defect was associated with akinesia or dyskinesia (Fisher's standardized Z = 9.14).(ABSTRACT TRUNCATED AT 250 WORDS)

Probenecid impairment of acetaminophen and lorazepam clearance: direct inhibition of ether glucuronide formation

Eleven subjects received acetaminophen (650 mg i.v.) on two occasions in random sequence, with and without concurrent administration of probenecid (500 mg) every 6 hr. Nine subjects similarly received lorazepam (2 mg. i.v.) with and without concurrent probenecid. Acetaminophen half-life was prolonged during probenecid treatment (mean +/- S.E., 4.30 +/- 0.23 vs. 2.51 +/- 0.16 hr; P less than .001) due to markedly decreased clearance (178 +/- 13 vs. 329 +/- 24 ml/min; P less than .001) with no change in volume of distribution (65 +/- 4 vs. 69 +/- 3 l; NS). Urinary excretion of acetaminophen glucuronide during 24 hr was decreased (84 +/- 9 vs. 260 +/- 21 mg of acetaminophen as glucuronide; P less than .001) and acetaminophen sulfate excretion was increased (323 +/- 25 vs. 217 +/- 17 mg of acetaminophen as sulfate; P less than .005) during concurrent probenecid treatment. However, the sum of the two conjugated metabolites was not significantly different (407 +/- 28 vs. 476 +/- 20 mg of acetaminophen as glucuronide plus sulfate excreted per 24 hr; NS). Lorazepam half-life was also prolonged during probenecid treatment (33.0 +/- 3.9 vs. 14.3 +/- 1.08 hr; P less than .001) due to decreased clearance (44.7 +/- 5.4 vs. 80.3 +/- 13.2 ml/min; P less than .001) with no change in volume of distribution (111 +/- 5 vs. 111 +/- 7 l; NS). Formation of the ether glucuronides of acetaminophen and lorazepam is impaired markedly by therapeutic doses of probenecid. Sulfate conjugation is not affected.(ABSTRACT TRUNCATED AT 250 WORDS)

Absolute and relative bioavailability of oral acetaminophen preparations

Eighteen healthy volunteers received single 650-mg doses of acetaminophen by 5-min intravenous infusion, in tablet form by mouth in the fasting state, and in elixir form orally in the fasting state in a three-way crossover study. An additional eight subjects received two 325-mg tablets from two commercial vendors in a randomized crossover fashion. Concentrations of acetaminophen in multiple plasma samples collected during the 12-hr period after each dose were determined by high-performance liquid chromatography. Following a lag time averaging 3-4 min, absorption of oral acetaminophen was first order, with apparent absorption half-life values averaging 8.4 (elixir) and 11.4 (tablet) min. The mean time-to-peak concentration was significantly longer after tablet (0.75 hr) than after elixir (0.48 hr) administration. Peak plasma concentrations and elimination half-lives were similar following both preparations. Absolute systemic availability of the elixir (87%) was significantly greater than for the tablets (79%). Two commercially available tablet formulations did not differ significantly in peak plasma concentrations, time-to-peak, or total area under the plasma concentration curve and therefore were judged to be bioequivalent.

Differential effect of cimetidine on drug oxidation (antipyrine and diazepam) vs. conjugation (acetaminophen and lorazepam): prevention of acetaminophen toxicity by cimetidine

Fourteen healthy volunteers received a single i.v. dose of antipyrine (1.2 g) on two occasions, once before and once during cimetidine treatment (300 mg every 6 hr). In a similar manner, 8 subjects received diazepam (10 mg), 11 subjects received acetaminophen (650 mg) and 8 subjects received lorazepam (2 mg), all by the i.v. route, once before and once during cimetidine coadministration. Pharmacokinetic analysis indicated increased antipyrine elimination T1/2 during cimetidine treatment (16.7 vs. 10.9 hr; P less than .001) on the basis of decreased total metabolic clearance (0.46 vs. 0.72 ml/min/kg; P less than .001). Likewise, diazepam T1/2 was increased (58 vs. 39 hr; P less than .01) during cimetidine treatment due to decreased total metabolic clearance (0.42 vs. 0.30 ml/min/kg; P less than .01). In contrast, cimetidine did not alter T1/2 or the clearance of lorazepam (T1/2, 16.8 vs. 15.3 hr; clearance, 1.03 vs 1.07 ml/min/kg) or acetaminophen (T1/2, 2.66 vs. 2.60 hr; clearance, 4.8 vs. 4.5 ml/min/kg), both drugs which undergo conjugative biotransformation. In an animal model used to assess the effect of cimetidine on acetaminophen toxicity, the LD50 of acetaminophen alone in Charles River CD-1 mice was 480 mg/kg (95% confidence interval: 436-528 mg/kg). With simultaneous 75 mg/kg of cimetidine treatment, the LD50 for acetaminophen was significantly increased (P less than .05) to 1020 mg/kg (95% confidence interval: 962-1081 mg/kg). Thus, cimetidine slows the metabolic clearance of antipyrine and diazepam, drugs biotransformed by hepatic oxidation, but does not alter the kinetics of acetaminophen or lorazepam, both metabolized by conjugation. Cimetidine may decrease the toxicity of high-dose acetaminophen by preventing formation of the hepatotoxic oxidative metabolites, although having no effect on conjugation of acetaminophen which yields nontoxic metabolites that are subsequently cleared from the body.

Effect of food on acetaminophen absorption in young and elderly subjects

Twenty-four healthy volunteers aged 22 to 78 years received 650-mg doses of acetaminophen (AAP) on five separate occasions. The modes of administration were: intravenous AAP by 5-minute infusion; oral AAP as two 325-mg tablets in the fasting state; oral AAP 650 mg as an elixir preparation in the fasting state; tablets with food; and elixir with food. Plasma concentrations of AAP were determined by high-pressure liquid chromatography for up to 12 hours after the dose. In both the young and the elderly groups, the four oral modes of administration were significantly different with respect to peak plasma concentration (P less than 0.001), time to peak plasma concentration (P less than 0.001), and systemic availability (P less than 0.01). Although food slowed the rate of absorption of both oral preparations, no significant difference in peak acetaminophen plasma concentration or time of peak concentration was observed as a function of age. Absolute systemic availability of elixir and tablets in the fasting state tended to be lower in the elderly subjects (P less than 0.05). However, when either preparation was coadministered with food, there were no differences between the two age groups. Thus, age as such does not appear to be a critical determinant in the design of oral acetaminophen dosage schedules.

Increased metabolic clearance of acetaminophen with oral contraceptive use

The effect of chronic low-dose oral contraceptive steroid use on the pharmacokinetics of intravenous acetaminophen was determined. Eight women using low-dose (under 50 micrograms) estrogen oral contraceptive steroid for more than 3 months were matched for age and weight (mean age, 25.9 years; mean weight, 58.3 kg) with 8 female controls not using the steroid (mean age, 26.0 years; mean weight, 55.5 kg). No subject was taking other drugs. Oral contraceptive steroid subjects had a lower elimination half-life of acetaminophen (2.12 hours) than controls (2.71 hours) (P less than .005). Volume of distribution was similar for both groups (oral contraceptive group, 1.04 liters/kg; controls, 0.96 liters/kg; NS). Total metabolic clearance was significantly higher in oral contraceptive subjects (5.81 ml/min/kg, versus 4.12 ml/min/kg for controls; P less than .02). As volume of distribution and body weight are similar for both groups, the decrease in acetaminophen elimination half-life among contraceptive steroid users is the result of increased total metabolic clearance. Thus, low-dose estrogen oral contraceptive steroid may stimulate the metabolism of a conjugatively metabolized drug such as acetaminophen, in contrast to contraceptive steroid impairment of the clearance of some oxidatively metabolized drugs, with antipyrine being the prototype.

Obesity, sex, and acetaminophen disposition

Twenty-one obese (14 women; 7 men) and 21 normal (11 women; 10 men) drug-free and age-matched subjects were given single 650-mg IV doses of acetaminophen. Mean total body weights (TBW) for the groups were as follows: obese men, 134.9 kg; control men 70.6 kg; obese women, 87.9 kg; and control women, 55.0 kg; ideal body weight (IBW) was similar for all of the groups. Acetaminophen elimination half-life (t1/2 beta) did not differ among groups. Absolute volume of distribution (Vd) was greater in obese than in control men (109 and 77 l, P less than 0.05) and greater in control men than in control women (77 and 52 l, P less than 0.05), but Vd corrected for TBW was smaller in obese than in control men (0.81 and 1.09 l/kg TBW, P less than 0.05) and smaller in obese than control women (0.71 and 0.95 l/kg TBW, P less than 0.05). Absolute metabolic clearance was greater in obese than in control men (484 and 323 ml/min, P less than 0.05), in obese than in control women (312 and 227 ml/min, P less than 0.05), and in control men than women (323 and 227 ml/min, P less than 0.05). After correction for TBW, however, clearance between control and obese subjects of the same sex did not differ. Acetaminophen Vd is increased in obesity and in men relative to women, but the drug's distribution into body weight exceeding IBW is less extensive than that into IBW. For men the distribution ratio is 0.44 and for women, 0.31. Acetaminophen clearance increases with body weight and therefore is much greater in obese patients and in men.

Age does not alter acetaminophen absorption

Twenty-eight healthy volunteers (age range, 22-78 years) received 650 mg of acetaminophen (AAP) on three separate occasions. The modes of administration were 1) intravenous, 5-minute infusion; 2) oral, with two 325-mg tablets; and 3) oral, with 650 mg as an elixir preparation. Plasma levels of AAP were determined in blood samples drawn up to 12 hours after the dose. The mean (+/- sd) kinetic variables for absorption of AAP from tablets in young and elderly were peak plasma concentration, 11.8 (+/- 4.2) vs 10.9 (+/- 4.1) micrograms/ml; peak time, 0.79 (+/- .54) vs 0.69 (+/- .40) hours after the dose; absorption half-life, 12.6 (+/- 9.8) vs. 8.2 (+/- 5.3) minutes; and absolute systemic availability, 79 (+/- 9) vs 72 (+/- 11) per cent. For AAP elixir, the corresponding values were 12.6 (+/- 5.4) vs 13.7 (+/- 6.0) micrograms/ml; 0.52 (+/- .24) vs 0.54 (+/- .51) hours; 8.6 (+/- 6.2) vs 6.1 (+/- 6.6) minutes; and 87 (+/- 9) vs 80 (+/- 9) per cent. Absolute bioavailability of both oral dosage forms was significantly less then 100 per cent in all groups. Elderly subjects tended to show lower availability of both oral preparations, but the difference was of borderline significance (P less than .50). Age did not influence any other measures of absorption. Since the absorption rate of acetaminophen may be indicative of the gastric emptying rate, age does not appear to alter this rate-limiting step in drug absorption.

Effect of food on ethambutol absorption

The effect of food on the absorption of ethambutol hydrochloride tablets was investigated. Following an overnight fast, 11 normal volunteers ingested ethambutol hydrochloride tablets (15 mg/kg dosage) once while fasting and once immediately following a standardized breakfast. The sequence of administration was assigned randomly. Food and fasting trials were at least seven days apart. In both trials, blood samples were drawn at 1, 2, 3, 4, 6, 8, 12, and 24 hours after dosing. Ethambutol concentrations in plasma were determined by a gas-chromatography method. Completeness of absorption was assessed by calculation of the area under the 24-hour plasma concentration curve (AUC) for each subject after each mode of administration using a trapezoidal approximation. Within-subject difference in AUC between food and fasting conditions was evaluated using the Student's t test for paired data. There was no significant difference between the mean AUC-fasting and the mean AUC-food (p greater than 0.05). Food does not appear to influence the extent of ethambutol absorption.

Acetaminophen kinetics in the elderly

Thirty-two healthy men and women, 23 to 78 yr old, received single 650-mg intravenous doses of acetaminophen and the drug's kinetics were determined from multiple plasma samples drawn over the next 8 to 12 hr. Acetaminophen elimination half-life averaged 2.7 hr (range, 1.9 to 4.3 hr) and was not related to age or sex. Volume of distribution (corrected for weight) was larger in men than in women (0.99 and 0.86 l/kg) and declined with age in both sexes. This probably reflects increased fat per kilogram body weight in women and in the elderly, together with incomplete distribution of this nonlipophilic drug into body fat. Acetaminophen clearance tended to decline with age in both sexes, but differences were of borderline significance. On the basis of kinetics data alone, adjustment of acetaminophen dosage for the elderly is generally not necessary.

Drug therapy reviews: evaluation of butorphanol tartrate

The chemistry, pharmacology, uses, side effects, pharmacokinetics and dosage of butorphanol tartrate, a narcotic analgesic with antagonist properties, are reviewed. When administered intramuscularly or intravenously, butorphanol tartrate appears to be as effective for relieving moderate to severe pain as are pentazocine, meperidine and morphine. Butorphanol produces sedation more commonly and, at therapeutic dosages, depresses respiration as much as these other narcotic analgesics. A limited number of long-term clinical studies suggest a lower physical dependence liability with butorphanol than with other narcotic analgesics. Butorphanol is more expensive than morphine and, for most patients, offers no significant advantages over morphine for short-term use. Because butorphanol's cardiovascular effects are not completely understood, morphine also remains the drug of choice for pain associated with myocardial infarction.

Acetaminophen

Acetaminophen is an effective mild analgesic and antipyretic agent. In double-blind, controlled experimental pain studies of short duration, acetaminophen is superior to placebo and produces analgesia comparable to that produced by aspirin. The frequency of adverse reactions to therapeutic doses of acetaminophen is low, as is that of aspirin. Overdosage with acetaminophen, however, may result in irreversible hepatotoxicity. Since clinical manifestations of intoxication can be of slow onset, physicians may tend to delay initiation of definitive therapy. Intravenous cysteamine, and possibly oral methionine, appear to be effective in preventing hepatotoxicity if they are administered with 10 h of drug ingestion. Physicians should be aware of the potential danger of acetaminophen overdosage and alerted to its clinical manifestations.

Inservice pharmacy technician training program

The development and implementation of a two-month inservice training program for hospital pharmacy supportive personnel is discussed. A task-oriented approach was used to define the instructional objectives of the program. To emphasize the job-related nature of the instruction, conferences and workshops were selected as the primary teaching methods. A specific instructional plan was designed for drug conferences, giving the trainee an active role in the learning of drug names and dosage forms. On-the-job experience, comprising 30% of the training time, gradually was incorporated into the program. Staff pharmacists and supervisors assumed the teaching responsibilities. During weekly evaluation sessions with each trainee, the coodinator discussed the trainee's performance, pin-pointed deficiencies and suggested means of improvement. The benefits of the program, in terms of selection and sequence of instructional programs, student assessment and program evaluation, are discussed.