Introduction
`
`The y-hydroxybutyric acid (GHB) is a structural
`analog of the y-aminobutyric acid (GABA).
`
`HO~OH
`
`0
`
`GHB
`
`GABA
`
`It is an endogenous substance with function of
`an inhibitory neurotransmitter in the central nerv(cid:173)
`ous system in mammals. Its natural concentration
`in the human brain is 0.3 mmol/g. However, the
`compound is able to pass the blood-brain barrier,
`which is unique for a neurotransmitter, and, thus,
`its concentration in cerebrospinal fluid (CSF) can
`be enlarged. The main mechanism of its action con(cid:173)
`sists in binding to a specific presynaptic GHB re(cid:173)
`ceptor which is coupled to a G protein [34]. Its fur-
`
`A. Wuszkidewicz, J. Bojarski
`
`ther elfect relies upon a decrease in adenyl cyclase
`activity.
`A receptor complex of GHB-GABA8 has also
`been reported and GHB was proved to be an ago(cid:173)
`nist of most GABA8 receptors [5]. The third obser(cid:173)
`ved mechanism involves an allosteric action on the
`calcium channels [19].
`Under physiological conditions, mm origi(cid:173)
`nates from GABA which is metabolized by a trans(cid:173)
`aminase to succinic semialdehyde and then by a de(cid:173)
`hydrogenase to GHB. Nevertheless, most of GABA
`is transformed to succinic acid which enters the
`Krebs cycle (Fig. I).
`
`Neuropharmacological action
`
`GHB can be found in both nerve and somatic
`cells and in body fluids such as blood and CSF.
`However, its function in the body outside the nerv(cid:173)
`ous system remains unknown .
`
`l ,4- Butanediol
`
`,OH
`.,-......
`.,......
`Ho·
`.._.,.--
`..__,,.
`
`Oxidation
`
`/ t
`
`c0 y 0
`O<d•OOo j ~ •
`
`0
`4-Hydroxybutanal Ho~
`I
`H
`
`Dehydratatio,r"'
`
`_J
`
`y-Butyrolactono
`
`y-Hydrnxybutyric acid HO~O ~·ransamination
`
`OH
`
`Oxtdalton
`
`.. /l
`I Reduction
`H
`/
`Succinic semialdehydo 0~0
`OH
`
`---------------
`H ,N~O
`OH
`
`/
`
`Ox1dat1vc /A , b . . d
`transamination
`y- rnmo utync ac,
`
`Oxidation l
`
`Succinic acid
`
`OH
`~o
`0
`I
`OH
`
`~ Krebs cycle
`
`Fig. 1. Metabolism of y-hydroxybutyric acid, y-aminobutyric acid, 1,4-butanediol and y-butyrolactone
`
`44
`
`Pol. J. Phannacol., 2004, 56, 43--49
`
`AMN1002
`IPR of Patent No. 8,772,306
`Page 451 of 1327
`
`

`

`y-HYDROXYBUl-YRIC ACID AND ITS DERIVATJVES
`
`The cerebral cortex
`Stimulation of the GHB-GABA13 receptor com(cid:173)
`plex in the frontal lobe oflhe cerebral cortex proba(cid:173)
`bly leads to absence seizures [2] due to inhibition
`of Ca2"' uptake (stimulated by K+ ions). Moreover,
`agonism at presynaptic GABA8 receptor results in
`lowered GABA release leading to the absence sei(cid:173)
`zures mentioned above [14, 33]. Another result of
`the GABA8 agonism is the hypnotic effect [37].
`An increase in endogenous acetylcholine level
`has been reported after GHB administration as well
`as an increase in serotonin synthesis and metabo(cid:173)
`lism [31].
`In the 1970s it was observed that morphine ele(cid:173)
`vated the GHB level and that GHB and morphine had
`synergic effect in producing euphoria {30]. Later, it
`was demonstrated that GHB increased synthesis of
`enkephalins, and that GHB-induced EEG change was
`reversed by naloxone [29]. Moreover, GI-IB was
`proved not to stimulate the µ, 8 and K opioid recep(cid:173)
`tors [25].
`In the temporal lobe, in the hippocampus,
`which is responsible for memory and learning, ago(cid:173)
`nistic action at the GABA8 receptors leads to
`guanyl cyclase activation, increase in cGMP level,
`and consequently to hyperpolanzation of hippo(cid:173)
`campal neurons. Such action is responsible for am(cid:173)
`nesia due to GHB ingestion.
`
`The thalamus
`
`A decrease in the excitatory postsynaptic poten(cid:173)
`tials in the thalamus has been reported. Such action
`is responsible for the anesthetic effect of GHBNa
`used as sodium oxybate (Somsanit) [9]. It is sus(cid:173)
`pected that the GHB-GABA8 receptor complex also
`can be formed in the ventrobasal nucleus in the
`thalamus and is responsible for absence seizures [l].
`
`The hypothalamus
`
`Administration of GHB results in activation of
`tyrosine hydroxylase and, as a result, the larger
`amount of dopamine is synthesized. Nevertheless,
`small doses of the drug decrease and its large doses
`increase secretion of dopamine [5].
`Secretion of dopamine in the striatum is de(cid:173)
`creased independently of the GHB dose.
`
`The limbic system
`
`The limbic system is responsible for the mood.
`Frequent stimulation of the reward system, espe-
`
`cially the extended amygdala, which includes the
`shell and the nucleus accumbens, with the same
`substance leads to addiction [27]. Such mechanism
`also concerns GHB ingestion [16].
`
`The cerebellum
`
`There are so few GHB receptors in the cerebel(cid:173)
`lum that the effect of their stimulation is merely no(cid:173)
`ticeable. What is observed in this structure is that
`GHB decreases the synthesis of nitric oxide, result(cid:173)
`ing in sudden reversible increase in blood pressure
`in the brain.
`
`The spinal cord
`
`Intraspinal GHB administration leads to hyper(cid:173)
`polarization of neurons in the spinal cord [26].
`
`The metabolic and endocrinologic effects
`
`Inhibitory effect of GHB on the GABA-keto(cid:173)
`glutaric acid transaminase leads to a decrease in
`glucose catabolism and greater tolerance of hypo(cid:173)
`xia [35]. Such an action can be considered as an ad(cid:173)
`vantage of GHB use in resuscitation [ 17].
`Another effect of the drug consists in increasing
`the growth ho1mone level, which was the reason why
`GI--IB became popular among body-builders [31].
`
`Toxicology
`
`Only I% of GHB is excreted with urine in the
`unchanged form [13]. Therefore, in order to meas(cid:173)
`ure its concentration in blood or urine, it is essential
`to use advanced chromatographic methods. One of
`them, using gas chromatography/mass spectrome(cid:173)
`try (GC/MS), allows to measure as small drug con(cid:173)
`centrations as 0.1 mg/J in plasma and 0.2 mg/l in
`urine, however, it requires conversion of GI-IB to
`y-butyrolactone (GBL) (acidification of samples)
`[10]. Another GC/MS analysis, which does not re(cid:173)
`quire the mentioned conversion, can be used for
`samples within the concentration range between
`0.5--2.0 mg/I [8, 18]. If a patient has ingested GEL
`which was partially converted to GHB in blood, it
`may be the easiest to use high performance liquid
`chromatography (T-IPLC) [13]. Another analytical
`procedure has recently been developed by Kimura
`et al. [!5] due to the need for higher sensitivity of
`tests. In addition, a new ultra-rapid procedure seems
`promising, because a valid result of the test is ac(cid:173)
`cessible within l h [36].
`
`ISSN I 23 D-60D2
`
`45
`
`AMN1002
`IPR of Patent No. 8,772,306
`Page 452 of 1327
`
`

`

`A. Waszkielewicz, J. Bojarski
`
`GHB is rapidly metabolized to succinic semialde(cid:173)
`hyde and then to succinic acid which enters lhe Krebs
`cycle (Fig. 1) and the final metabolic products are
`CO2 and H20. Therefore, 4--6 h after the GHB in(cid:173)
`gestion it may be impossible to measure its concen(cid:173)
`tration in urine [20, 28].
`Acute intoxication can be entirely cured within
`6 h in cases when it does not impair respiratory ac(cid:173)
`tivity [22].
`Some dose- and blood concentration-effect re(cid:173)
`lationships are summarized in Tables 1 and 2.
`
`Chemical modifications of GHB
`
`Trans-4-hydroxycrotonic acid (T-HCA) (I)
`
`T-HCA was proved to be an endogenous sub(cid:173)
`stance in the CNS [3]. It is able to bind to the GHB
`receptor and it was the first compound that showed
`properties required for a substance to be capable of
`reacting with the GHB receptor. Firstly, the active
`
`form of the compound must be non-lactonic. Sec(cid:173)
`ondly, there is small tolerance of the distance be(cid:173)
`tween the carboxyl and the hydroxyl groups.
`
`1,4-Butancdiol (II)
`
`l ,4-Butanediol is much more lipophilic than
`GHB. Therefore, it passes through the blood-brain
`barrier much faster and clinical effects are observed
`sooner than after GHB ingestion. However, in the
`CNS it is transformed to GHB as it is shown m Fig(cid:173)
`ure 2. It should be noticed that administration of
`any alcohol dehydrogenase inhibitor, such as etha(cid:173)
`nol or 4-methylpyrazole, prevents the sedative ef(cid:173)
`fect from development after GHB ingestion. D1sul(cid:173)
`firam, which is an inhibitor of aldehyde dehydroge(cid:173)
`nase, partially abolishes
`the sedative effect.
`Therefore, it seems that 1,4-butanediol (1,4-BD)
`acts after being metabolized to GHB and/or to
`GABA [ 4, 38].
`
`alcohol
`~OH dchydrogenase
`HO
`
`aldehyde
`dehydrogenase HO~OH
`0
`
`Fig. 2. l ,4-Butanediol metabolism to y-hydroxybutyric acid
`
`HO~ ,
`- ~OH
`
`0
`
`lram A-hydroxycrotonic acid (I)
`
`Cl ~
`
`OH
`
`0
`
`4-chlorobutyric acid (III)
`
`~
`HO
`
`OH
`
`l,4-butanediol (II)
`
`0 ~
`
`H C/
`'
`
`0H
`
`11
`0
`
`4-metoxybu\yric acid (IV)
`
`rY'CI
`~
`
`HO~ONa
`
`0
`
`NCS-356
`
`sodium 4-hyclroxy-5-p-ch!oropheny!pentanoate (V)
`
`HO~ONa
`
`HO~
`
`0
`
`UMB68
`
`sodium 4-hydroxy-4-melhylpentanoate (VI)
`
`Fig. 3. GHB-related co mpounds
`
`OH
`
`O
`
`UMB58
`
`5- hyd:roxypentanoic acid (Vil)
`
`46
`
`Pol. J. Pharmacol., 2004 , 56, 43-49
`
`AMN1002
`IPR of Patent No. 8,772,306
`Page 453 of 1327
`
`

`

`y-HYDROXYHUTYRlC ACJD AND ITS DERIVATIVES
`
`Table 1. The relationship between the dose and the effect of
`GHJ3 in patients [ 6]
`
`Dose (g)
`---·-··-····--···--·------------
`below 0.7
`euphoria, sociability
`
`Effect
`
`0.7--1.4
`
`l.5--2. l
`
`2.1-3.5
`
`3.5--4.9
`
`short amnesia
`
`weariness and sleep
`
`intensification of the above effects
`
`hypnosis, hypotonia, weak analgesia
`
`Table 2. The relationship between the GHB concentration in
`blood and the state of consciousness in patients J l 2]
`
`n NH'(\) Nu
`
`H
`
`I
`
`--'"
`
`~ /
`C
`H,
`
`OH
`
`N-benz.ylamide of o..-(benzyhuni:nc)--f-h)ldruxybulyric acid (Ylll)
`
`n NH~0 Nl):
`
`~ /
`C
`H,
`
`H
`
`I
`
`/,'
`
`OH
`
`State of consciousness
`
`N-(o---t:hlorobe"")'l)-amidt: of a.-(bc:nzylamlnt:)·'r-h)"rlroxybutyric- acid (IXJ
`
`GHB concentration
`in blood (mg/l)
`
`over 260
`
`156-260
`
`52-156
`
`patients in coma and did not react to
`pain stimuli
`
`patients asleep and did react to pain
`stimuli
`
`patients showed spontaneous
`movements and occasi anally opened
`their eyes
`
`below 52
`
`patients woke up
`
`- - - - - - - - +4·- • ··· •···-• ··· V~ ·-<a··v·.
`
`,·v " '" •••• • • • • • • • • · - - - -
`
`a-(4-Phcnylpiperazinc)-y-hydroxybut)lric acid :md
`a-(4-bcneylpiperazinc)-y-hydroxybutyric !lc:id derivatives (X)
`
`n .. 0 or l
`rn -
`I or 2 (form - 2 R ~ H)
`R ~ H, 2-CI, 4-CI, 4-f, 4-CH1, 4-0C:H,, 3.~-(0Cll, ),
`
`C4-substituted derivatives
`
`Fig. 4. Anticpileptic derivatives ofy-hydroxybutyric acid
`
`Both 4-chlorobutyric acid (III) and 4-metho(cid:173)
`xybutyric acid (IV) have stronger ability to cause
`absence seizures [21] (Fig. 3).
`NCS-356, sodium 4-hydroxy-5 -p-chlorophe(cid:173)
`nylpentanoate (V), is a specific GHB receptor ago(cid:173)
`nist used for receptor studies. However, it is rapidly
`metabolized in the organism [37].
`The following compounds have been studied
`for both GHB receptor agonism and their potential
`metabolism [37]. Both UMB68 (VI) and UMB58
`(Vll) are specific GHB receptor agonists. UMB68,
`sodium 4-hydroxy-4-methylpentanoate, is not me(cid:173)
`tabolized by oxidases due to a change in the pri(cid:173)
`mary alcohol group (GHB) into the tertiary one
`(UMB68). Therefore, it is used for GHB receptor
`studies. UMB58, 5-hydroxypentanoic acid, can be
`another compound proving the tolerance of the dis(cid:173)
`tance between the carboxyl and the hydroxyl group
`in the acid for the GHB receptor agonism.
`Both compounds: N-benzyl-a-(benzylamine)
`-y-hydroxybutanamide (VITI) and N-(o-chloroben(cid:173)
`zyl)-a-(benzylamine)-y-hydroxybutanamide
`(IX)
`(Fig. 4) have been synthesized within the American
`Antiepileptic Drug Development {ADD) program
`
`and chosen as effective and the least toxic among
`this group of substances. Within the range of
`promising compounds, there are also a-(4-phenyl(cid:173)
`piperazine)-y-hydroxybutyric acid and a-(4-benzyl(cid:173)
`piperazine)-y-hydroxybutyric acid derivatives (X)
`[19).
`
`Cyclic compounds
`
`Among cyclic compounds tested for their influ(cid:173)
`ence on different seizures, there are y-thiobutyrola(cid:173)
`ctone (XI) and GBL (XII) (Fig. 5). The former has
`the potential of causing grand ma! seizures [21)
`and the latter, as GHB precursor, causes pelit ma/
`seizures. It is suspected that GBL is first hydro(cid:173)
`lyzed to GHB in blood by the serum esterases, then
`the GHB passes through the blood-brain barrier
`and in the CNS it reacts with the GHB receptor.
`
`NCS-382
`
`The pharmacological GHB receptor antagonist,
`NCS-3 82 ( 6, 7 ,8 ,9-tetrahydro-5-[H]benzocyclo-he(cid:173)
`pten-5-ol-4-ylideneacetic acid) (Xllf) (Fig. 5), and
`especially its (R)-isomer [7], is accessible in NIDA
`
`ISSN 1230-6002
`
`47
`
`AMN1002
`IPR of Patent No. 8,772,306
`Page 454 of 1327
`
`

`

`A. Waszkielewicz, J. Bojarski
`
`procedures to test GHB, 1,4-BD and/or GBL is im(cid:173)
`pressive as it seems to meet requirements of emer(cid:173)
`gency toxicology departments.
`
`y-Thiobutyrolactone (XI)
`
`·1-Butyrolaclonc (GBL) (XII)
`
`REFERENCES
`
`(1) 0
`~HN
`
`OH
`
`NCS-382 (6,7,8,9 tctrahydro-5-[H]benzocyclohepten-
`5-ol-4-ylideneacctk acid) (XIII)
`
`Fig 5. Cyclic derivatives ofGHB
`
`(National Institute on Drug Abuse) for studies on
`the GHBergic system. It is able to antagonize GHB
`action, up to a certain GHB dose, due to the other
`mechanisms of action reported for GHB [24].
`NCS-382 is also able to antagonize seizures of dif(cid:173)
`ferent sources other than those caused by GHB, al(cid:173)
`though clinical data do not suggest that the effec(cid:173)
`tiveness is always satisfactory [32].
`
`Valproic acid and cthosuximide
`
`The GHB dehydrogenase inhibitors, valproic
`acid (Depakene, Valproate, Valrelease) and etho(cid:173)
`suximide (Zarontin), which are common antiepi(cid:173)
`leptic medicines, intensify all the effects observed
`after administration of GHB [11, 23]. The effect is
`observed due to inhibited GHB metabolism.
`
`Conclusions
`
`The recent 40 years of studies on pharmacologi(cid:173)
`cal aspects of GHB action in mammalian brain
`have brought a large amount of information con(cid:173)
`cerning the GHB synaptic system and the role of its
`agonists in the brain. However, certain problems,
`such as the distribution of the GHB-GABA8 com(cid:173)
`plex or different sensitivity of GABA8 receptors,
`still remain unsolved. Certain substances with
`proved action on the GHBergic system require fur(cid:173)
`ther studies and much more specific data are ex(cid:173)
`pected. Nevertheless, the development of analytical
`
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`Page 455 of 1327
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`

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`Received: July 21, 2003; in revisedfonn: November 26,
`2003.
`
`ISSN 123 0-6002
`
`49
`
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`Page 456 of 1327
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`Eur J Clin Pharmacol (1997) 52: 351-358
`
`IPihiridttR•i•iT•itd#•iM-
`
`© Springer-Yedag 1997
`
`K. Wesnes · P. M. Simpson· B. Jansson· A. Grahnen
`H-J. Weimann· H. Kiippers
`Moxonidine and cognitive function: interactions
`with moclobemide and lorazepam
`
`Received: 3 June 1996 / Accepted in revised form: 18 February 1997
`
`Abstract Objective: Moxonidine represents a new gen(cid:173)
`eration of centrally acting antihypertensive drugs. It
`binds to 11-imidazoline receptors and exerts its antihy(cid:173)
`pertensive activity through a reduction in systemic vas(cid:173)
`cular resistance, while cardiac output remains un(cid:173)
`changed or even increases slightly. Moxonidine is pre(cid:173)
`treatment of mild
`to moderate
`scribed
`for
`the
`hypertension. Typical doses are 0.4 to 2.0 mg given as
`one dose in the morning or as divided doses in the
`morning and evening.
`Me1hods: The effects of moxonidine 0.4 mg once daily in
`combination with moclobernide or lorazepam were in(cid:173)
`vestigated in two, double- blind, randomised, placebo(cid:173)
`controlled, two-way crossover studies in a total of 48
`healthy volunteers. Safety assessments were made in
`each study and included pre- and post-study measure(cid:173)
`ment of blood pressure, heart rate, ECG, haematology,
`blood biochemistry, and urinalysis, and recording of
`adverse events.
`Results: In the first study, moxonidine alone was found
`to produce small but statistically significant impairments
`of vigilance detection speed at 4 hand 6 h. Lowering of
`subjective alertness was also observed. Repeat dosing
`with moxonidine produced an impairment of memory
`scanning performance. These findings were not repro(cid:173)
`duced in the second study, in which moxonidine alone
`produced an improvement in immediate word recall at
`4 hand 6 h.
`No interactions were observed when moxonidine was
`co-administered with moclobemide. Moxonidine, when
`co-administered with lorazepam, produced interactions
`
`K. Wesnes (12l)·P.M. Simpson
`Cognitive Drug Research Limited, Priory Court,
`Beech Hill, Reading RG7 2BJ, UK
`
`B. Jansson· A. Grahnen
`PMC Contract Research AB, Islandsgatan 2,
`S-753 18 Uppsala, Sweden
`
`H-J. Weimann· H. Ki.ippers
`Solvay Pharmaceut1cals, Hans-Bockler-Allee 20,
`D-30173 Hannover, Germany
`
`with three tasks requiring high levels of attention:
`choice, simple reaction time and digit vigilance perfor(cid:173)
`mance; memory tasks; immediate word recall, delayed
`word recall accuracy; and visual tracking.
`A total of 47 adverse events were reported in study l.
`Moxonidine produced a slight decrease of systolic and
`diastolic blood pressure. In study 2, a total of 55 adverse
`events were reported. In both trials, the most frequently
`reported events were tiredness and dryness of mouth, the
`latter occurring only under the moxonidine treatment.
`There were no clinically relevant changes observed in
`blood pressure, pulse rate, and laboratory tests in either
`study, nor was there any evidence of any interaction
`between moxonidine and either moclobemide or lo(cid:173)
`razepam.
`Conclusion: Moxonidine was found to be safe and well
`tolerated in healthy volunteers. However, the impair(cid:173)
`ments on attentional tasks were greater when moxoni(cid:173)
`dine was co-administered with lorazepam I mg. These
`effects should be considered when moxonidine is co(cid:173)
`dosed with lorazepam, although they were smaller than
`would have been produced by a single dose oflorazepam
`2mg.
`
`Key words Moxonidine, Cognitive function; moclobemide,
`lorazepam, 11-imidazoline-receptor, drug interaction,
`memory, attention, computerised cognitive assessments
`
`Introduction
`
`( 4-chloro-N-{ 4,5-dihydro- l H-imidazol-2-
`Moxonidine
`y 1)-6-methoxy-2-meth y l-5-pyrimidine) or (4-chloro-5-(2-
`imidazolidin-2-ylimino )-6-methyl-pyrimidine) represents
`a new generation of centrally acting antihypertensive
`drugs. It exerts its antihypertensive activity through a
`reduction in systemic vascular resistance, while cardiac
`output remains unchanged or even increases slightly [4}.
`Moxonidine binds to I 1-imidazoline receptors and thus
`exercises its regulatory effects on the arterial blood
`pressure and heart rate (6, IO].
`
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`352
`
`Pharmacokinetic studies have characterised moxoni(cid:173)
`dine with low protein binding, a short plasma half-life, a
`long duration of blood pressure reduction, a low rate of
`metabolism, an absolute bioavailability of about 90%,
`excretion via the kidneys, no accumulation, no interac(cid:173)
`tion with glibenclamide, digoxin or hydrochlorothiazide,
`no interaction with food, and similar kinetic profiles in
`the young and elderly [16].
`In clinical trials, of 2500 subjects and volunteers ad(cid:173)
`ministered moxonidine, 370 received the drug for 1 year
`or longer. Doses have ranged between 0.2 and 0.4 mg
`once per day, although doses up to 2 mg have been
`administered and have been well tolerated. Typical ad(cid:173)
`verse effects are dry mouth and fatigue which are dose
`dependently mild and transient [8, 11]. Moxonidine does
`not undergo first pass hepatic metabolism, is loosely
`bound to plasma proteins and is excreted largely un(cid:173)
`changed in urine [14, 13, 16]. These are indications that
`moxonidine can be administered to most patients suf(cid:173)
`fering from co-existing diseases, taking concomitant
`medication, or both.
`In clinical practice, patients on long-term anti-hy(cid:173)
`pertensive therapy may occasionally require treatment
`with either a benzodiazepine or a monoamine oxidase
`inhibitor. The purpose of the studies was to simulate
`such situations and to investigate the possible conse(cid:173)
`quences for cognitive function. Lorazepam and moc(cid:173)
`lobemide were selected since data on their cognitive
`effects had already been obtained using the comput(cid:173)
`erised test system to be employed in the study [5, 9,
`17, 18J.
`Lorazepam is a widely used benzodiazepine used in
`the treatment of anxiety and epilepsy, and as a pre(cid:173)
`medicant. It is known to impair a wide range of cogni(cid:173)
`tive functions including those associated with attention,
`memory and subjective ratings of alertness [5, 9].
`Moclobemide is a benzamide used in the treatment of
`depression and melancholic syndromes. As well as
`showing no interaction with alcohol [ 17, 18], previous
`work with moclobemide in the elderly has shown few
`cognitive effects of the drug compared with trazodone.
`This paper reports the results of two separate studies
`of the effects of moxonidine on cognitive performance.
`Study 1 investigated the effects of moxonidine and
`moclobemide, when administered alone, and the poten(cid:173)
`tial interaction of moxonidine when co-administered
`with moclobemide. Study 2 investigated the effects of
`moxonidine and lorazepam alone, as well as the poten(cid:173)
`tial interaction of moxonidine with lorazepam. In each
`study, both safety assessments (blood pressure, pulse
`rate, ECG, and laboratory tests) and the recording of
`adverse events were undertaken.
`Therefore, the primary objective of these studies was
`to detennine the pharmacodynamic effects of moxoni(cid:173)
`dine 0.4 mg once daily when taken with moclobemide
`300 mg once daily or lorazepam 1 mg once daily using
`computerised tests of cognitive function in healthy vol(cid:173)
`unteers. The secondary objective of the studies was to
`investigate the safety profile of moxonidine alone and
`
`when co-administered with moclobemide and loraze(cid:173)
`pam.
`
`Methods
`
`Study population
`
`Volunteers were male and female, Caucasian, aged between 18 and
`45 years and within 10% of their ideal weight. In study I (moc(cid:173)
`lohemide), 24 (13 male, 11 female) volunteers, mean age 23 (SD 3)
`years, mean weight 68 (SD 9) kg were included in the study. In
`study 2 (lorazepal11), 24 (12 male, 12 female) volunteers, mean age
`23 (SD 3) years, mean weight 67 (SD 9) kg were included in the
`study. Screening (pre- and post-study) included a medical history,
`physical examination, 12-lead ECG, routine laboratory tests
`(haematology, blood chemistry, urinalysis, and for drugs of abuse,
`HIV and hepatitis B), and, where appropriate, a pregnancy test.
`Volunteers were excluded if they had taken any drug or medication
`7 days prior to the start of the study, or any investigational
`medication 2 months prior to the start of the study. The study was
`approved by an ethics committee, and signed written informed
`consent was obtained from all volunteers before their participa(cid:173)
`tion.
`
`Study design and study medication
`
`Both studies were of the same design - randomised, double-blind,
`two-way cross-over, and placebo-controlled - in which all 24 vol(cid:173)
`unteers completed two treatment periods of 6 days separated by a
`minimum 7-day wash-out period. The volunteers were assigned
`randomly to receive oral doses of each of tile treatment combina(cid:173)
`tions. In study 1, volunteers received two 0.2-mg moxonidine tab(cid:173)
`lets in the morning for 6 days, or 2 placebo moxonidine tablets. On
`day 6, volunteers also received two 150-mg moclobemide tablets in
`the morning. In study 2, the dosing regime was the same as that for
`study 1 with the exception that on day 6, volunteers also received
`one ]-mg lorazepam tablet in the morning in place of two moc(cid:173)
`lobemide tablets.
`The administration of the moclobemide or lorazepam was open.
`On days I, 5 and 6, dosing was undertaken at the Research Centre.
`On days 2, 3 and 4, dosing was undertaken at home, with the times
`of dosing recorded on a diary card by the volunteers.
`Alcohol and tobacco were prohibited during the study, and
`caffeine intake was restricted.
`
`Assessments
`
`The assessments and assessment procedures were the same for both
`studies and were as follows: subjects underwent folir training ses(cid:173)
`sions during period 1, two being conducted on the day prior to
`dosing and two being conducted on day I of the trial. Assessments
`were made before, and I, 2.5, 4, 6 and 8 h post dosing . The as(cid:173)
`sessments were performed in the following sequence: cog111tive
`performance tests then adverse event recordings
`
`Cognitive performance tests
`
`A selection of tests from the Cognitive Drug Research Comput(cid:173)
`erised Assessment System was used [5, 9, 17, 18, 15]. This system
`was run by a suite of programs installed on IBM-PC compatible
`machines, which control all aspects of testing, selecting appropriate
`parallel forms and recording all responses with millisecond accu(cid:173)
`racy. Task information was presented via colour monitors and
`responses to the tests were made using one of two response buttons,
`"YES" or " NO", on a single response module. The following tasks
`were atempted:
`
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