Timber rattlesnake (Crotalus horridus): Biology, conservation, and envenomation in the Upper Mississippi River Valley (1982-2020).

The Timber Rattlesnake (Crotalus horridus) is the largest pit viper in the Northern United States and is the prominent venomous snake species indigenous to the bluff land habitats of the Upper Mississippi River Valley (UMRV). Conservation of C. horridus in this geographic region not only preserves the ecosystem's biodiversity and ecological balance, but also assures the continued study of their biomedically important venoms/toxins. Field studies of C. horridus biology and natural history performed from 1985 to 2015 in southeastern Minnesota and western Wisconsin along the Mississippi River showed populations have declined. Consequently, the implementation of improved conservation measures afforded the species protective status in both states. Historically, accounts of Timber Rattlesnake bites in the UMRV have been sparse, and medical consequences of envenomation have had limited documentation. However, in recent decades cases of envenomation by C. horridus have continued to occur. Retrospective analysis of clinical toxinology consultations documented from 1982 to 2020 on cases of envenomation by C. horridus in the UMRV revealed a very low incidence of bites annually and revealed that their venom can induce a rapid and precipitous decline in platelets.

Crotalus morulus (Viperidae: Crotalinae) envenoming and treatment with F(ab')2 antivenom.

We present the first published case of Tamaulipan Rock Rattlesnake (Crotalus morulus) envenoming. A 54-year-old male professional herpetologist was bitten on the left thumb by a captive C. morulus. Pain, swelling, bruising, and pressure in the thumb were experienced within minutes. On presentation, he reported 7/10 pain and had firm edema in his thumb and thenar eminence. Initial laboratory studies showed normal platelet count, PT, PTT, and creatine kinase. He was treated with pain medication and 10 vials of crotalidae immune F(ab')2 (equine) antivenom approximately 3 h post envenoming. Lymphangitic streaking and axillary lymphadenopathy developed, followed by progression of edema, emergence of a hemorrhagic bulla, and declining platelets, prompting treatment with two additional 10-vial antivenom doses. His platelet count declined to 125 × 103/µL 24 hours post envenoming and he developed numbness in his thumb. Following antivenom therapy completion no further decline in platelets occurred and thrombocytopenia improved to 131 × 103/µL prior to discharge 46 hours post envenoming; fibrinogen, PT, PTT, and CK remained normal. He had no residual signs or symptoms 5 months later. C. morulus venom includes proteolytic venom enzymes that induce local soft tissue destruction, pain, and edema with ecchymosis and blister formation. Although C. morulus venom contains a unique disintegrin, morulustatin, no fibrinogenolytic activity was observed.

Latrodectus geometricus (Aranea: Theridiidae) envenoming: Rapid resolution of symptoms following F(ab')2 antivenom therapy.

The Brown Widow spider (Latrodectus geometricus) is an invasive species whose geographic range has been expanding worldwide. It is a relative species of the Black Widow and Red-backed spiders of the genus Latrodectus. Despite its broad geographic distribution cases of Brown Widow envenomation have rarely been documented. The venom of L. geometricus is similar to the venom of L. mactans with the primary venom component being alpha-latrotoxin, and consequent envenoming by L. geometricus to humans has resulted in symptoms similar to those reported for other Latrodectus spp. Specific FDA approved Latrodectus antivenom (IgG) available in North America has been effectively used in treating venom-induced symptoms following L. mactans envenoming. The patient reported here involved a confirmed L. geometricus envenoming who was efficaciously treated with an alternately available F(ab')2 antivenom from Mexico.

Crotalus durissus terrificus (viperidae; crotalinae) envenomation: Respiratory failure and treatment with antivipmyn TRI® antivenom.

We report an envenomation to a professional herpetologist by a South American rattlesnake (Crotalus durissus terrificus) that resulted in respiratory failure, and therapeutic improvement following antivenom administration. A 56-year-old male was bitten on the left wrist by a Crotalus durissus terrificus (C. d. terrificus) while attempting to tube the snake for maintaining safe control while performing venom extraction. The patient was intubated due to rapidly ensuing respiratory failure and administration of Antivipmyn-TRI® was initiated while being transported via ambulance. The patient was admitted to the hospital unconscious and unresponsive. Mechanical ventilation was required until 5 h after completion of antivenom administration. No significant adverse effects were observed with antivenom administration. The patient was discharged approximately 55 h following envenomation. This is the first reported case in the United States of a patient following a C. d. terrificus envenomation with consequent respiratory failure, and in which Antivipmyn-TRI® was successfully administered.

Enhanced immunogenicity of a bivalent nicotine vaccine.

The efficacy of nicotine vaccines for smoking cessation is dependent upon their ability to elicit sufficiently high serum antibody concentrations. This study compared two nicotine immunogens representing different hapten presentations, 3'-aminomethyl nicotine conjugated to recombinant Pseudomonas exoprotein A (3'-AmNic-rEPA) and 6-carboxymethlureido nicotine conjugated to keyhole limpet hemocyanin (6-CMUNic-KLH), and assessed whether their concurrent administration would produce additive serum antibody concentrations in rats. Effects of vaccination on nicotine pharmacokinetics were also studied. Vaccination of rats with these immunogens produced non cross-reacting nicotine-specific antibodies (NicAb). Serum NicAb concentrations elicited by each individual immunogen were not affected by whether the immunogens were administered alone as monovalent vaccines or together as a bivalent vaccine. The total NicAb concentration in the bivalent vaccine group was additive compared to that of the monovalent vaccines alone. Higher serum NicAb concentrations, irrespective of which immunogen elicited the antibodies, were associated with greater binding of nicotine in serum, a lower unbound nicotine concentration in serum, and lower brain nicotine concentration. These results demonstrate that it is possible to design immunogens which provide distinct nicotine epitopes for immune presentation, and which produce additive serum antibody levels. The concurrent administration of these immunogens as a bivalent vaccine may provide a general strategy for enhancing the antibody response to small molecules such as nicotine.

Hyperglycemia in acute aluminum phosphide poisoning as a potential prognostic factor.

Aluminum phosphide (AlP) is a solid fumigant widely used in Iran as a grain preservative. When reacted with water or acids, AIP produces phosphine gas, a mitochondrial poison that interferes with oxidative phosphorylation and protein synthesis. Poisoning by AIP is one of the most important causes of fatal chemical toxicity in Iran. There are few studies in the medical literature addressing prognostic factors associated with AlP poisoning. In this prospective study conducted across a 14-month period commencing on 21st March 2006, we enrolled all patients admitted to the ICU of Loghman-Hakim Hospital Poison Center (Tehran, Iran) with AIP poisoning, no history of diabetes mellitus diagnosed before hospitalization, and normal body mass index. We recorded patient-specific demographic information, blood glucose level on presentation (before treatment), arterial blood gas (ABG) analysis, time elapsed between ingestion and presentation, ingested dose, duration of intensive care admission, and outcome data related to each presentation. We enrolled the group of patients who survived the intoxication as a control group and compared their blood glucose levels with those who died because of AlP poisoning. Data were analyzed by Statistical Product and Service Solutions (SPSS) software (Version 12; Chicago, Ilinois, USA) using logistic regression, Pearson correlation coefficient and Student's t-test. P values of 0.05 or less were considered as the statistical significant levels. Forty-five patients (21 women and 24 men) with acute AlP poisoning were included in the study. The mean age was 27.3 +/- 11.5 years (range: 14-62 years). Thirteen patients survived (29%) and 32 expired (71%). AlP poisoning followed deliberate ingestion in all patients. The time elapsed between ingestion and arrival at the hospital was 3.2 +/- 0.4 h. There was no significant difference between survived and non-survived groups according to age, gender, and time to treatment. However, the difference between mean blood glucose levels in survived (143.4 +/- 13.7 mg/dL) and non-survived (222.6 +/- 20 mg/dL) cases was statistically significant (P = 0.021). There was no significant correlation between blood glucose level and time to treatment, age, gender, pH, HCO3 concentration, and ingested dose. Twenty-three (71.9%) of non-survived and four (30.8%) of survived patients had a blood glucose level greater than 140 mg/dL. After adjusting according to age, gender, ingested dose, pH and HCO3 concentration The odds ratio for hyperglycemia as a risk factor for death was 5.7 (CI of 1.4-23.4). In our study, patients who succumbed to AIP poisoning had significantly higher mean blood glucose levels than those who survived. This correlation of hyperglycemic effect and mortality suggests that it may be useful in guiding risk assessment and treatment of AIP poisoning. Management of hyperglycemia may have a useful role in treatment of these patients by allowing increased entrance of glucose into cells and reducing oxygen consumption.

Changes in maternal and fetal nicotine distribution after maternal administration of monoclonal nicotine-specific antibody to rats.

Vaccination against nicotine to elicit the production of nicotine-specific antibodies is a potential treatment for tobacco addiction which reduces nicotine distribution from serum to brain. Vaccination of pregnant rats also reduces the distribution of maternally-administered nicotine to the fetal brain. Whether this is due to maternal antibody reducing the transfer of nicotine from mother to fetus, or to fetal antibody altering the distribution of nicotine within the fetus, is not clear. In the current study, passive immunization of rats with the murine monoclonal nicotine-specific antibody Nic311 was used as a surrogate for vaccination because antibody transfer to the fetus was anticipated to be lower than with vaccination. Pregnant rats received nicotine from gestational day (GD) 18-20 as frequent i.v. boluses to simulate nicotine exposure from smoking. Nic311 was administered at doses of 30, 80 or 240 mg/kg on GD 19. Fetal serum Nic311 levels on GD 20 were <3% of concurrent maternal levels, but concentrations of up to 20 ug/ml in fetal serum were obtained owing to the very high levels in maternal serum. Accumulation of the chronically administered nicotine, measured on GD 20, was not changed by Nic311 treatment in either maternal or fetal brain. The early distribution of nicotine to maternal brain, measured 5 min after a dose, was markedly reduced by Nic311, while the early distribution of nicotine to whole fetus and fetal brain was not substantially altered. These data suggest that the limited transfer of Nic311 to the fetus in turn limits the ability of Nic311 to reduce nicotine distribution to the fetal brain.

Vaccination against nicotine does not prevent nicotine-induced changes in fetal nicotinic receptor binding and c-fos mRNA expression in rats.

Gestational exposure of rats to nicotine produces long-lasting alterations in brain development. Vaccination of adult female rats against nicotine reduces the distribution of maternally administered nicotine to fetal brain, suggesting that vaccination might protect against these effects. In the current study, the effects of vaccination on nicotine-induced changes in fetal (3)H-epibatidine binding and c-fos mRNA expression were evaluated using tissue from a previous pharmacokinetic study of vaccination. An intermittent nicotine dosing regimen designed to resemble nicotine intake in a smoker was administered from GD1-20. Peak nicotine levels in fetal brain were reduced by vaccination, whereas the chronic accumulation of nicotine in fetal brain was not. Gestational nicotine exposure produced significant increases in (125)I-epibatidine binding to brain and spinal cord on GD20, and decreased c-fos mRNA expression in fetal striatum, adrenal and lung. Vaccination did not significantly alter these effects. These data suggest that nicotine dosing, using a clinically relevant intermittent bolus dose regimen, produces substantial changes in fetal nicotinic receptor and c-fos mRNA expression. The decrease in c-fos mRNA expression contrasts with previously reported increases, and suggests that the nicotine dosing regimen used may influence its effects. The lack of effect of vaccination suggests that the cumulative exposure of fetal tissues to nicotine may influence the measured parameters to a greater extent than peak exposure levels.

Local envenomation from the bite of a juvenile false water cobra (Hydrodynastes gigas; Dipsadidae).

The false water cobra (Hydrodynastes gigas) is a non-front-fanged colubroid snake frequently exhibited in zoos, and maintained by amateur collectors. Little detailed documentation regarding the time-course of symptoms development and the consequences of their bites to humans has been published. Reported here is a case of envenoming in a 25 yo male that occurred after the bite of a juvenile H. gigas. The victim was bitten on the fourth digit of the left hand while processing the snake for sex determination, and the snake remained attached to the digit for approximately 30 s; there was no jaw advancement. Within 5 min, intense local pain developed, and at 4hr post bite the entire dorsal aspect of the hand was significantly edematous, The local effects progressed and involved the entire forearm, and the local pain referred to the axillary region. Mild paresthesia and local blanching ("pallor") were noted in the affected digit, but resolved within 7 days. The clinical course in the patient showed that moderate localized symptoms may result from the bite of a juvenile H.gigas.

Effects of alpha-1-acid glycoprotein administration on propranolol binding and beta blockade in rats.

Alpha-1-acid glycoprotein (AAG), 750 mg/kg, was administered to rats to determine its effect on propranolol binding and beta blockade. Anesthetized rats received [3H]propranolol i.v., followed in 15 min by human AAG or bovine serum albumin, 750 mg/kg. AAG treatment produced a human AAG concentration in serum of 7.76 +/- 1.17 mg/ml, several times higher than the endogenous serum AAG concentration in stressed rats. AAG treatment significantly increased the heart rate response to isoproterenol, compared to albumin (95.4 +/- 19.6 vs 28.3 +/- 16.7% of baseline value, measured 45 min after propranolol, P less than 0.001). AAG-treated rats had greater [3H]propranolol binding in serum (93.0 +/- 3.2 vs 76.7 +/- 3.0%, P less than 0.01) and a lower calculated unbound [3H]propranolol concentration in serum (2.7 +/- 1.3 vs 7.4 +/- 3.1 X 10(6) dpm/ml, P less than 0.001) than albumin-treated rats. These data demonstrate that AAG can alter propranolol pharmacokinetics and pharmacodynamics even when administered after the propranolol effect is evident. Because the reported affinity of propranolol for cardiac beta receptors is 10,000 times greater than its affinity for AAG, these data suggest that AAG acted by altering propranolol disposition rather than by directly competing with beta receptors for drug.

Determination of the in vivo antigen-antibody affinity constant from the redistribution of desipramine in rats following administration of a desipramine-specific monoclonal antibody.

Quantitative expressions have been derived to determine the affinity constant for the in vivo interaction of an antigen with its elicited monoclonal antibody by analysing the redistribution of antigen following antibody administration. Using this method, the intrinsic binding constant for the interaction of subtoxic doses of DMI in rats with anti-TCA was found to be about two orders of magnitude less than the value obtained in vitro. The disparity is probably due to the presence of endogenous ligands for the antibody.

Redistribution and enhanced urinary excretion of 2,2',4,4',5,5'-hexachlorobiphenyl (HCB) in rats using HCB-specific IgG and Fab fragments.

Drug-specific antibody fragments can enhance the elimination of some drugs by redistributing drug from tissues into serum and allowing renal excretion of the drug-antibody complex. This approach could potentially be used to enhance the elimination of compounds such as polychlorinated biphenyls that have very long elimination half-lives. As a first step in testing this hypothesis, the effects of 2,2',4,4',5,5'-hexachlorobiphenyl (HCB)-specific antibodies and their corresponding Fab fragments on HCB disposition were studied in rats. Antibodies to HCB were produced in chickens, and the corresponding Fab fragments were produced by digestion with papain. To study antibody effects on HCB distribution, [14C]HCB (0.1 mg) was administered i.v. to rats. Two weeks later, after distribution to tissues was complete, anti-HCB IgG or control IgG was administered i.v. The serum radiolabel concentration 2 hr after IgG administration increased 185 +/- 64% in animals treated with specific antibody vs 51 +/- 19% in control animals (P < 0.001). The increase in serum radiolabel concentration was apparent within 30 min and maximal at 2 hr. To study effects on HCB excretion, anti-HCB or control Fab fragment was administered 2 weeks after [14C]HCB. Urinary HCB excretion over the next 24 hr, measured by gas chromatography, was 10-fold greater in the group treated with anti-HCB Fab (P < 0.01). These data demonstrate that anti-HCB IgG can redistribute HCB rapidly from tissues into serum and that anti-HCB Fab can enhance urinary HCB excretion. While the magnitude of these changes was small, the data suggest that increasing HCB excretion using drug-specific antibody fragments is feasible, and can serve as a model for enhancing the excretion of compounds that have very long elimination half-lives.

Effects of recombinant drug-specific single chain antibody Fv fragment on [3H]-desipramine distribution in rats.

Tricyclic antidepressant overdose can be reversed in rats by drug-specific antibody Fab fragments, but the required Fab dose may itself by toxic. We studied the potential use of a smaller, recombinant desipramine (DMI)-specific single chain Fv fragment (B9-sFv) for this purpose. Anesthetized rats received a tracer (subtoxic) dose of [3H]-DMI followed in 15 min by B9-IgG, B9-Fab, B9-sFv (0.1 mumol of binding sites) or BSA. Each of the active treatments produced a rapid and substantial increase in the serum radiolabel concentration, whereas BSA did not (P < 0.001). The increase in serum radiolabel concentration 1 min after treatment was 13.3-fold with B9-IgG, 10.0-fold with B9-Fab and 7.3-fold with B9-sFv. Serum antibody concentrations were also highest after B9-IgG and lower with B9-Fab or B9-sFv. The 24-hr urinary excretion of radiolabel did not differ among groups, but was extensive even in the BSA group and probably represented the excretion of DMI metabolites. B9-sFv concentrations in urine or buffer at 37 degrees declined by >90% over 24 hr, but this fragment was much more stable in serum, retaining 70% of its activity after 96 hr. These data demonstrate that B9-sFv can alter markedly the distribution of [3H]-DMI in vivo. The rapidity of this effect, and its magnitude in comparison with Fab fragment or IgG, suggest that further study of B9-sFv as a treatment of DMI overdose is warranted.

Immunization of rats reduces nicotine distribution to brain.

The effect of active immunization against nicotine on the initial distribution of nicotine to brain was studied in anesthetized rats. Animals received nicotine 0.03 mg/kg nicotine (equivalent to the nicotine dose absorbed by a human smoking two cigarettes) as a rapid injection in the jugular vein. In control animals, the arterial serum nicotine concentration initially exceeded the venous concentration 4.6-fold, similar to the initial arteriovenous difference produced by cigarette smoking in humans. Animals immunized with the nicotine analog CMUNic maintained this arteriovenous gradient, but with both arterial and venous nicotine concentrations several times higher than in controls. The arterial nicotine concentration was higher in immunized animals even at the first (7.5 s) sampling time. The brain nicotine concentration at 3 min was 36% lower in the immunized animals. The time course of nicotine distribution to brain was studied in a second group of animals. Brain nicotine concentration was reduced in rats immunized with CMUNic over the entire 6-min sampling period immediately following nicotine dosing (mean reduction 38%). A reduction was found at the earliest sampling time (30 s) and was maximal at 1 min (48%). Nicotine protein binding in serum was markedly increased in animals immunized with CMUNic compared to controls (91.2 versus 10.9%), and the unbound nicotine concentration in serum was lower (10.0 versus 13.4 ng/ml). The reduction in brain nicotine concentration correlated with antibody affinity for nicotine, and the percentage of nicotine bound in serum. These data demonstrate that nicotine-specific antibodies produced by active immunization rapidly bind nicotine in arterial blood, reduce the unbound nicotine concentration, and reduce the early distribution of nicotine to brain. Effects were observed using a clinically relevant nicotine dose and route of administration. These data suggest that the use of immunization to modify the behavioral effects of nicotine may be possible.

Tissue-dependent effects of immunization with a nicotine conjugate vaccine on the distribution of nicotine in rats.

Vaccination of rats against nicotine reduces nicotine distribution to brain even at nicotine doses greatly exceeding the estimated binding capacity of the available antibody. This observation suggests a differential effect by which vaccination reduces nicotine distribution to brain to a greater extent than to other tissues. To test this hypothesis, vaccinated rats received a single intravenous nicotine dose equal to twice the estimated binding capacity of nicotine-specific antibody in vaccinated rats. The total and bound serum nicotine concentrations were higher in the vaccinated rats compared to controls, while the unbound serum nicotine concentration was lower. Distribution of nicotine to brain was reduced in vaccinated rats in a time-dependent manner, with a greater reduction at 1 min (64%) than at 25 min (45%). Vaccination reduced nicotine distribution to muscle, testis, spleen, liver, heart, and kidney, but to a lesser extent than to brain, while nicotine distribution to fat was increased. Chronically infused nicotine showed a similarly altered pattern of tissue distribution in vaccinated rats, but differences were in general smaller than after a single nicotine dose; brain nicotine concentration was 24% lower in vaccinated rats, while lung nicotine concentration was higher. The presence of nicotine-specific antibody in tissues may have contributed to the increased nicotine concentrations in fat and lung. These data suggest that vaccination reduces nicotine distribution to brain not only by sequestering nicotine in serum but also by redirecting tissue distribution disproportionately away from brain, such that nicotine concentrations are reduced to a greater extent in brain than in other tissues.

Hypertonic sodium bicarbonate partially reverses QRS prolongation due to flecainide in rats.

Hypertonic (1M) sodium bicarbonate can partially reverse the cardiac toxicity of some Class IA antiarrhythmic agents, presumably by antagonizing sodium channel inhibition. We studied the effects of 1M sodium bicarbonate on toxicity due to the Class IC drug flecainide. Anesthetized rats received i.v. loading and maintenance doses of flecainide to produce QRS prolongation of 76% that was stable over the 60 min study period. 20 min after the start of the maintenance infusion, groups of 8 rats received an i.v. infusion of 1M sodium bicarbonate (6 meq/kg) or an equal volume of 0.9% saline. QRS prolongation was reduced by 1M sodium bicarbonate but not only 0.9% saline (% change -12.2 +/- 10.0 v. +3.0 +/- 2.7, p = 0.001). Expressed as a percent of the flecainide-induced QRS prolongation, bicarbonate reduced this prolongation by 26.5%. The improvement in QRS duration persisted until sacrifice 30 min later. Compared to controls, the bicarbonate group had a significantly higher blood pH (7.55 +/- 0.06 v. 7.44 +/- 0.05) and serum sodium concentration (149 +/- 5 v. 137 +/- 2 meq/l). Serum flecainide concentrations were similar. These data suggest that 1M sodium bicarbonate can partially reverse flecainide-induced conduction delay in rats. This effect may be due to changes in the extracellular pH and sodium concentration. 1M sodium bicarbonate may be useful in assessing the role of sodium channel inhibition in mediating the toxicity of flecainide or other Class IC drugs.

Pretreatment with drug-specific antibody reduces desipramine cardiotoxicity in rats.

The effect of a drug-specific antibody on desipramine (DMI) cardiotoxicity was studied in rats. Animals were pretreated i.v. with 4.2 g/kg of a monoclonal antibody (anti-TCA) followed by DMI HCl 30 mg/kg i.p. (molar ratio of anti-TCA binding sites to DMI = 0.56). Peak QRS complex prolongation was substantially lower after pretreatment with anti-TCA than after control antibody (70 +/- 14 v. 21 +/- 4%, p less than 0.001). Time to peak toxicity was the same in both groups. Binding of DMI by anti-TCA was demonstrated by a higher serum total DMI concentration and increased DMI binding in serum after anti-TCA compared to controls. The DMI concentration in anti-TCA treated animals was lower in some organs (brain, lung, liver, spleen), but not in others (heart, muscle, kidney, fat). The calculated fraction of the DMI dose bound by anti-TCA was 19.9%. The steepness of the DMI dose-response curve was examined by administering DMI alone (without antibody) at various doses to rats. Compared to 30 mg/kg DMI, a dose reduction of 30-50% was needed to reduce QRS duration to the same extent as anti-TCA pretreatment. We conclude that DMI cardiotoxicity was markedly reduced by the binding of a relative small fraction of the DMI body burden to anti-TCA. This disproportionate effect of DMI binding was not due to the steepness of the DMI dose-response curve, nor to slowing of the rate of DMI distribution to tissues.

Drug-specific antibodies as antidotes for tricyclic antidepressant overdose.

Drug-specific antibodies have been used clinically to treat digoxin or colchicine overdose. The lethal dose of tricyclic antidepressants (TCAs) is 100 times higher, and will require higher doses of antibodies (up to several g/kg) to reverse toxicity. Preliminary studies suggest that this is feasible. High affinity TCA-specific monoclonal Fab' or polyclonal Fab fragments rapidly reverse the cardiovascular toxicity of the TCA desipramine (DMI) in rats, and prolong survival. TCA-specific Fab' or Fab is generally well tolerated in rats, but doses several times higher than anticipated for human use may have adverse effects. Combining Fab with standard therapies for TCA overdose, such as NaHCO3, can reduce the required Fab dose. As an alternative, a recombinant single chain Fv fragment (sFv), one half the size of Fab, has been cloned which retains a high affinity for DMI and is able to alter DMI distribution in vivo. Because sFv has a shorter elimination half-life and more extensive renal excretion than Fab, it may have therapeutic advantages.

Pharmacokinetics and toxicity of high-dose human alpha 1-acid glycoprotein infusion in the rat.

The pharmacokinetics of high-dose human alpha 1-acid glycoprotein (AAG) was studied in rats to determine the feasibility of using AAG to alter the tissue distribution of basic drugs. alpha 1-Acid glycoprotein (2.2 g/kg) was administered iv to six male Holtzman rats over a period of 30 min, and serum AAG concentrations were measured by a specific radial immunodiffusion assay. The AAG concentrations were computer fit to a biexponential equation to generate pharmacokinetic constants for an open two-compartment model. The peak serum AAG concentration was 1830 +/- 180 mg/dL at the end of infusion; greater than 20 times the normal value for rats. The central volume of distribution and steady state volume of distribution were 0.09 +/- .02 and 0.15 +/- 0.02 L/kg, respectively. Total body clearance of AAG was 0.065 +/- 0.005 L/kg/h, and the terminal elimination half-life was 19.3 +/- 1.5 h. The AAG administration was tolerated without adverse effect and did not alter systolic blood pressure, the electrocardiogram, creatinine clearance, weight gain, or survival. The results of the histologic examination of various tissues by light microscopy at 30 d post AAG treatment were normal. These data demonstrate that high doses of human AAG can be safely administered to rats and that they produce supraphysiologic serum AAG concentrations.

A nicotine conjugate vaccine reduces nicotine distribution to brain and attenuates its behavioral and cardiovascular effects in rats.

Vaccination of animals to elicit drug-specific antibodies, or the passive transfer of such antibodies from other animals, can reduce the behavioral effects of drugs such as cocaine and heroin. To study the potential application of this approach to treating nicotine dependence, IgG was isolated from rabbits immunized with a nicotine-protein conjugate vaccine. Anesthetized rats received immune IgG containing nicotine-specific antibodies (Nic-IgG) or control-IgG i.v.. Thirty minutes later, rats received nicotine at 0.03 mg/kg i.v., equivalent on an mg/kg basis to the nicotine intake from two cigarettes by a smoker. Compared to control-IgG, Nic-IgG reduced the brain nicotine concentration in a dose-related manner (65% reduction at the highest IgG dose). Pretreatment with Nic-IgG also reduced the distribution to brain of five repeated doses of nicotine (equivalent to the nicotine intake from 10 cigarettes) administered over 80 min. To study blood pressure effects, rats received control-IgG or Nic-IgG 1 day prior to administering nicotine. Nicotine-induced systolic blood pressure increases were attenuated by Nic-IgG in a dose-related manner, and were almost completely blocked by the highest Nic-IgG dose. Pretreatment with Nic-IgG also completely prevented the nicotine-induced stimulation of locomotor activity observed in rats receiving control-IgG. Nic-IgG did not prevent locomotor activation from cocaine, demonstrating its specificity for nicotine. These data demonstrate that the administration of nicotine-specific antibodies can reduce or prevent some of the pharmacokinetic, cardiovascular, and behavioral consequences of nicotine in rats. Effects were observed at nicotine doses and nicotine serum concentrations equal to or exceeding those typically associated with nicotine exposure in cigarette smokers. A potential role for immunization in the treatment of nicotine dependence is suggested.